Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1980-1984  (17,115)
  • 1970-1974  (11,615)
  • Polymer and Materials Science  (25,897)
  • Computational Chemistry and Molecular Modeling  (2,075)
  • Electron microscopy  (757)
  • Nuclear reactions
Source
Material
Years
Year
Keywords
  • 101
    Electronic Resource
    Electronic Resource
    Matrix-method calculation of linear and circular dichroism spectra of nucleic acids and polynucleotides (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 435-470 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Calculations of the optical properties (absorption, linear dichroism, circular dichroism, and anisotropic components of the CD) are presented for polynucleotides of random or regular sequence within the formalism of the matrix method using a set of parameters that includes only the ππ* transitions of the aromatic bases. Experimental solution spectra agree favorably with calculated CD spectra for A-RNA, A-DNA, and B-DNA, when coordinates derived from x-ray studies on fibers are used. Excessive hypochromicity is predicted when parameters intended to reproduce the vacuum-uv absorption of the chromophores are included in the calculations, but total elimination of these parameters leads to an insufficient hypochromicity for the long-wavelength absorption band. Using alternative conformations for DNA in low-salt aqueous solution did not improve the agreement between experimental and calculated spectra, but some features of the optical properties predicted for these variant structures suggest that the tilt of the bases with respect to the helical axis may be larger than that of the fiber B-form.In the case of polynucleotides with regular structure, which have been traditionally less easy to understand in terms of the standard nucleic acid conformations, a series of alternative structures has been examined. Unexpectedly, the calculated spectrum for the Z-DNA structure compares almost quantitatively with the experimental spectrum of poly(dGC·dGC) in low salt. This result, which confirms a recent report [Vasmel, H. & Greve, J. (1981) Biopolymers 20, 1329-1332], is in contrast with the current identification of Z-DNA with the high-salt form of poly(dGC·dGC). Finally, the optical properties of single-stranded polyribonucleotides appear to be better explained when alternative structures [91-helix for poly(rA) and 61-helix for poly(rC)] are introduced instead of the A-RNA form.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230305
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 102
    Electronic Resource
    Electronic Resource
    Total intensity light scattering from short, optically anisotropic wormlike chains (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 607-608 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230314
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 103
    Electronic Resource
    Electronic Resource
    Dimensions of short, rodlike macromolecules from translational and rotational diffusion coefficients. Study of the gramicidin dimer (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 611-615 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230402
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 104
    Electronic Resource
    Electronic Resource
    Alternative pathways in diffusion-collision controlled protein folding (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 675-694 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The diffusion-collision model of protein folding has been solved exactly for a three-microdomain protein subunit. Numerical analysis shows that the exact kinetics may be excellently approximated in all cases studied by a standard chemical kinetics approach with the forward rate constants calculated from the mean folding time formula found previously.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230408
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 105
    Electronic Resource
    Electronic Resource
    Electric birefringence study of the purple membrane of Halobacterium halobium (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 707-718 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An electric birefringence study was carried out on aqueous suspensions of the purple membrane of Halobacterium halobium. In addition to the characterization of both native and modified membrane samples, the dependence of electric birefringence on pH and ionic strength was also investigated. The results indicate that purple membrane shows electric birefringence at a field strength as low as 200 V/cm. The permanent dipole moment and polarizability ranged from 20,500 debyes and 1.01 × 10-14 cm3 for a purple membrane concentration of 0.40 mg/mL to 41,000 debyes and 2.05 × 10-14 cm3 for a concentration of 0.80 mg/mL. It was also found that removal of the retinyl group of bacteriorhodopsin substantially decreases but does not eliminate the electric birefringence of the membrane. The solubilization of the membrane by Triton X-100, however, completely abolishes the electric birefringence. These experiments indicate that there is an interaction between adjacent bacteriorhodopsin molecules within the purple membrane via the retinyl chromophore moiety that builds up the permanent dipole moment. They also suggest that there are two types of response when purple membrane suspensions are placed in an electric field. One is an alignment of the disk-shaped particles with the field. The other is a stacking of the particles following their alignment by the electric field, which is promoted by the induced dipole moment.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230410
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 106
    Electronic Resource
    Electronic Resource
    Folded β-turns and collagenlike conformations of -Gly-Pro- and -Pro-Gly-sequences in synthetic polytripeptides (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 617-621 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230403
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 107
    Electronic Resource
    Electronic Resource
    Computer building of β-helical polypeptide models (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 23-38 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A general method is presented for computing the atomic coordinates of helices in which a dipeptide is the repeating unit. The method will generate both single- and double-stranded model helices having idealized bond lengths and angles, and any arbitrary, user-specified, pitch and number of residues per turn. The variation of inter- and intrastrand hydrogen bonds with pitch and number of residues per turn can thus be examined. An application of the method is the construction of a β-helix having pitch of 6.3 Å per turn and 4.85 residues per turn, a model which can pack nicely into the unit cell of crystals of cation-bound gramicidin A.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230104
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 108
    Electronic Resource
    Electronic Resource
    Conformational change in yeast tRNAAsp (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 71-81 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure of yeast tRNAAsp in aqueous solutions has been analyzed in the light of results obtained from Raman spectra recorded at from 5 to 82°C and compared to those of tRNAPhe. Firm evidence is given of a reversible conformation transition for tRNAAsp at 20°C. This transition is observed for the first time in the tRNA series. The low-temperature conformation appears to have a more regular ribose-phosphate backbone and a more effective G base-stacking. This conformational change, which occurs essentially in the D loop, could be connected to the existence of two (A and B) crystal forms obtained depending on crystallization conditions. The melting temperatures, which are different for each base stacking in tRNAAsp, lie in a range of about 70°C, much higher than for tRNAPhe. This fact is interpreted by a higher ratio of G-C base pairs in tRNAAsp.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230107
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 109
    Electronic Resource
    Electronic Resource
    Interaction of poly-5-bromouridylic acid. I. Formation of helical complexes with various adenine and 2-aminoadenine derivatives (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 493-509 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexes of poly(BU) with various adenine derivatives were investigated by circular dichroism (CD) and absorption spectroscopy. A 1:2 stoichiometry was indicated on CD mixing curves for typical complexes of 9-substituted adenine and 2-aminoadenine derivatives with poly(BU). The CD spectrum of adenosine·2poly(BU) is characterized by well-resolved bands in the range of 210-350 nm. Other adenine derivative-poly(BU) complexes also afford similar CD spectra, while 2-aminoadenine derivative-poly(BU) complexes give quite different spectra. Attempts to assign representative CD spectra were made using the transition of helical poly(BU) and the respective purine polynucleotides. The similarity of the CD spectra suggests that poly(A)·2poly(BU) and adenine derivative-poly(BU) complexes are nearly identical in structure except for the ribose-phosphate linkage. The fact that the uv isosbestic point of adenosine·2poly(BU) falls in close proximity to that of the corresponding polymer complex also supports this conclusion. In the formation of stable helices, the ribose moiety is dispensable in the “strand” of purine. The Tm of 9-methyladenine·2poly(BU) is somewhat higher than that of adenosine·2poly(BU) under equivalent conditions. The Tm difference with the monomer-poly(U) system was found to be about 20°C in 0.4M NaCl-0.02M Na-cacodylate-5 × 10-4M EDTA (pH 7.0). Further, it was noted that the monomer-poly(BU) complexes are formed even when the Tm is lower than that of self-folded poly(BU).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230307
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 110
    Electronic Resource
    Electronic Resource
    31P-NMR studies of deoxyoligonucleotides (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 575-592 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The assignments of 31P resonances of eight short oligonucleotides have been achieved through specific heterodecoupling techniques reported previously from our laboratory [Cheng et al. (1982) Biopolymers 21, 697-701]. The temperature dependence of the assigned 31P chemical shifts of these oligomers was studied and compared to the constitutive dimeric units. This comparison gives some insight to the chemical-shift values of the phosphorus resonances of oligonucleotides. (1) The 3′-end terminal phosphorus resonance in an oligomer tends to locate at a spectral position relatively close to its constitutive dimeric unit. (2) On chain elongation (from 5′-toward 3′-end), the phosphorus resonance in the oligomer will be shifted upfield by 0.2-0.3 ppm, as compared to its constitutive dimeric unit. (3) The relative positions of phosphorus resonances in an oligomer tend to remain in the same order as their constitutive dimeric units. The above obsrvations lead to the development of a new procedure to assign the 31P resonance of a single-stranded oligonucleotide.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230311
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 111
    Electronic Resource
    Electronic Resource
    L-Alanyl-glycylglycine: FT-IR and Raman spectroscopic evidence for tripeptide packing in a collagenlike arrangement (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 623-627 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230404
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 112
    Electronic Resource
    Electronic Resource
    Viscometry and sedimentation equilibrium of partially hydrolyzed hyaluronate: Comparison with theoretical models of wormlike chains (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 647-666 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fractionated samples of sodium hyaluronate of low molecular weight were used to calibrate the carbazole method for glucuronyl analsis and to determine the density increment (based on dry weight) of 0.444 (±0.003) mL/g in water and 0.386 (±0.003) mL/g for samples dialyzed against 0.2M NaCl. Weight-average molecular weights obtained by high-speed sedimentation equilibrium were used to calibrate the limiting viscosity number [η] in 0.2M NaCl, which gave [η]/Mw = 0.0028 (±0.0002) mL/g, valid to Mw = 0.0028 (±0.0002) mL/g, valid to Mw = 105. Experimental data from this work and the literature, including viscosity and light- and small-angle x-ray scattering measurements, were compared to theoretical chain models of the Kratky-Porod (KP) wormlike and the helical wormlike (HW) chain, as treated by Yamakawa and collaborators. Although either model could be fitted to experimental data about equally well with consistent parameters, provided those for the HW chain were of weakly helical nature, calculation of the unperturbed meansquare end-to-end distance as a function of chain length from a conformational model favored the KP chain alternative. The parameters that provide the best fit to experimental data for the KP wormlike model are a persistence length of 4.5-5 nm and a diameter of 1.1 nm. The latter is resonable for a hydrated hydrodynamic cylinder in view of the approximate unhydrated value of 0.7 nm estimated from the density increment.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230406
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 113
    Electronic Resource
    Electronic Resource
    Cation-induced conformational changes in tRNA molecules (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 759-766 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The uv absorption spectra and melting profiles of an initially ion-free solution of E. coli unfractionated tRNA are significantly modified by the addition of either Na+, Mg2+, or Mn2+ or of other first-series transition-metal ions such as Ni2+, Co2+, and Zn2+. The main effect of the addition of all monovalent or divalent cations examined is an increase of the ordered and stacking stabilized tRNA structure, as revealed by a drop in the absorption near 260 nm, as well as in the 4-TU absorption region. Sharp differences have, however, been detected in the 290-305-nm range in the presence of the various ions studied. When transition-metal ions were added to a tRNA solution, an absorption peak appeared at 294 nm. This effect is interpreted as a perturbation of the electronic structure of the bases due to direct binding of metal ions to the bases. An analysis of the variation in the spectrum as a function of metal concentration and of the thermal melting reversibility in the presence of various metal ions supports the conclusion that while all ions investigated are involved in binding to the phosphate groups of tRNA, transition-metal ions are also able to bind directly to the bases.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230414
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 114
    Electronic Resource
    Electronic Resource
    Electrostatic interactions between α-helix dipoles in crystals of an uncharged helical undecapeptide (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 809-817 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electrostatic interactions between α-helix dipoles in the crystals of an uncharged helical undecapeptide have been studied in detail. The electrostatic interaction energy between one helix dipole and its 26 nearest neighbors is approximately -23 kcal mol-1. A very similar result is obtained when calculating the interactions between one helix dipole and all 988 helix dipoles occurring within a distance of 75 Å. It therefore appears that in these crystals of completely uncharged molecules large, favorable electrostatic interactions occur.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230418
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 115
    Electronic Resource
    Electronic Resource
    Modeling biological macromolecules in solution. II. The general tri-axial ellipsoid (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 843-843 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230421
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 116
    Electronic Resource
    Electronic Resource
    Most-probable distribution at enzyme depolymerization of polysaccharides (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 859-876 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several research groups have studied depolymerizing processes by enzyme cleavage using product distribution. Although only the shortest chain products can be measured experimentally, interpretation of much evidence requires an assumption of the nature of high polymer distribution. The present work analyzes the high polymer distribution of products on the basis of mathematical models suggested for the two most widespread α-amylase action-mechanisms. The most-probable distribution was found to be distorted by hydrolysis only for the shortest chain products. The size of the distorted region is directly dependent on the characteristics of a specific enzyme. We studied the distribution of products for substrates of varying composition to show that it approaches the most-probable distribution at depolymerization.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230504
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 117
    Electronic Resource
    Electronic Resource
    Conformation study on heparin by intermediate-angle X-ray scattering (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 995-1009 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformation of heparin in water was investigated by intermediate-angle x-ray scattering (IAXS). The theoretical scattering function for the coil conformation was calculated by the Monte Carlo method using the approximation of separable conformation energies and the conformation energies computed for two disaccharide pairs in heparin. From x-ray scattering in a relatively small-angle region, the conformation of heparin is not the ordered 21 helix conformation but the coil conformation obtained by the Monte Carlo calculation. It is expected, from x-ray scattering in a relatively wide-angel region, that the sulfate groups of heparin maintain about 7 Å between them.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230603
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 118
    Electronic Resource
    Electronic Resource
    Study of polysaccharides by the fluorescence method. III. Chain length dependence of the micro-Brownian motion of amylose in an aqueous solution (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1043-1056 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The fluorescence polarization method was applied to the investigation of the micro-Brownian motion of amylose chains having a wide range of degree of polymerization (DP). We prepared two types of fluorescent conjugates of amylose: amylose conjugated with fluorescein randomly throughout the chain (F-amylose) and amylose conjugated locally on a terminal segment (t-F-amylose). The degree of fluorescence polarization of these conjugates was measured by changing the solvent viscosity at a constant temperature (25°C). The data obtained were analyzed by a Perrin-type equation to calculate the mean rotational relaxation time, 〈ρ〉. By examination of the plots of 〈ρ〉 vs DP, and by comparison of 〈ρ〉 with the theoretical rotational relaxation time of the whole molecule at a given DP, it was found that 〈ρ〉 mainly reflects the segmental motion of the amylose chain in the high-DP range. Thus, the fact that 〈ρ〉 for t-F-amylose is much smaller than that for F-amylose at a sufficiently high DP shows that a terminal segment undergoes a more rapid micro-Brownian motion than interior segments. In the low-DP range, we felt that the rotational diffusion of the whole molecule contributes significantly to the relaxation process. We also examined, for comparison, the segmental motion of dextran and pullulan in a similar manner and found that these segmental motions are more rapid than those of amylose. Based on the results obtained, the segmental mobility and conformation of the amylose molecule are discussed in relation to its chain length.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230606
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 119
    Electronic Resource
    Electronic Resource
    Synthesis and properties of L-cysteinyl-L-cysteine disulfides (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1085-1097 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oligomeric cyclic disulfides, obtained by mild oxidation of the fully protected dipeptide L-cysteinyl-L-cysteine, have been isolated by gel and thin-layer chromatography. Polymeric material was recycled by a thiol-disulfide exchange-reaction performed at basic pH. Spectroscopic investigations of the monomer and the two dimers indicate that conformers characterized by dihedral angles about the S—S bond close to ±90° are preferred. Moreover, chiroptical and 1H-nmr data for these compounds suggest higher mobility for the two dimers. The antiparallel dimeric disulfide can be considered a model compound for the hinge region formed at the subunit interface of the bovine seminal ribonuclease, a dimeric enzyme showing a complex kinetic behavior.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230609
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 120
    Electronic Resource
    Electronic Resource
    Dynamic light scattering as a probe of superhelical DNA-intercalating agent interaction (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1113-1119 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polarized dynamic light-scattering measurements on superhelical pBR322-plasmid DNA solutions in 0.2M NaCl, 2 mM NaPi, pH 7.0, 2 mM EDTA result in a translational diffusion coefficient DT,20°C0 = (3.77 ± 0.10) × 10-8 cm2/s for the native molecule. Modeling the DNA, in the simplest approximation, as a 10 × 440-nm effective hydrodynamic rigid rod yields a good fit to the apparent diffusion coefficient angular-dependence data up to 70°; the model fails at higher angles, probably due to the effects of flexibility or branching of the rod. Diffusion coefficient titration experiments with a platinum complex intercalating agent (PtTS) result in a titratable superhelix density of σ = -0.079 ± 0.008 under our experimental conditions, corresponding to about 34 superhelical turns in the native DNA. The DNA contour length predicted by our two independent results, the rod dimensions and the number of superhelical turns, is in excellent agreement with the contour length calculated from the number of base pairs, supporting the hydrodynamic approximation of an effective rodlike structure for this small DNA molecule in solution.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230611
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 121
    Electronic Resource
    Electronic Resource
    Quasi-harmonic method for studying very low frequency modes in proteins (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1099-1112 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A quasi-harmonic approximation is described for studying very low frequency vibrations and flexible paths in proteins. The force constants of the empirical potential function are quadratic approximations to the potentials of mean force; they are evaluated from a molecular dynamics simulation of a protein based on a detailed anharmonic potential. The method is used to identify very low frequency (∼1 cm-1) normal modes for the protein pancreatic trypsin inhibitor. A simplified model for the protein is used, for which each residue is represented by a single interaction center. The quasi-harmonic force constants of the virtual internal coordinates are evaluated and the normal-mode frequencies and eigenvectors are obtained. Conformations corresponding to distortions along selected low-frequency modes are analyzed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230610
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 122
    Electronic Resource
    Electronic Resource
    Temperature dependence of the dynamic light scattering of linear φ29 DNA: Implications for spontaneous opening of the double-helix (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1137-1137 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230613
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 123
    Electronic Resource
    Electronic Resource
    Contributions of synthetic polymers of amino acids to knowledge of immune response (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1141-1141 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230615
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 124
    Electronic Resource
    Electronic Resource
    Interaction of poly(I)·poly(C) with trans-dichloro-diammine-platinum (II) (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1143-1143 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230616
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 125
    Electronic Resource
    Electronic Resource
    Analysis of the high- and low-spin soret bands of horse-heart metmyoglobin complexes (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1147-1167 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Interest in the thermodynamics of the iron-binding site in hemoproteins has increased in recent years due to refinements in x-ray crystallographic studies of hemoproteins [see Deathage, J. F., Lee, R. S., Anderson, C. M. & Moffat, K. (1976) J. Mol. Biol. 104, 687-706; Heidner, E. J., Ladner, R. C. & Perutz, M. F. (1976) J. Mol. Biol. 104, 707-722; Deathage, J. F., Lee, R. S. & Moffat, K. (1976) J. Mol. Biol. 104, 723-728; Ladner, R. C., Heidner, E. J. & Perutz, M. F. (1976) J. Mol. Biol. 114, 385-414; Fermi, G. & Perutz, M. F. (1977) J. Mol. Biol. 114, 421-431; Takano, T. (1977) J. Mol. Biol. 110, 537-568 and 569-589], the synthesis and x-ray analysis of model heme compounds [see Scheidt, W. R. (1977) Acc. Chem. Res. 10, 339-345; Kastner, M. E., Scheidt, W. R., Mashino, T. & Reed, C. A. (1978) J. Am. Chem. Soc. 100, 666-667; Mashiko, T., Kastner, M. E., Spartalian, K., Scheidt, W. R. & Reed, C. A. (1978) J. Am. Chem. Soc. 100, 6354-6362; Hill, H. A. O., Skite, P. P., Buchler, J. W., Luchr, H., Tonn, M., Gregson, A. K. & Pellizer, G. (1979) Chem. Commun. 4, 151-152; and Scheidt, W. R., Cohen, I. A. & Kastner, M. E. (1979) Biochemistry 18, 3546-3556], and the numerous data on heme-protein interactions that account for the differences observed in ligand binding between the various species of animals. Numerous probes have been used and provide information about the structure and thermodynamics of the binding site, but no single probe can provide the complete picture [see Iizuka, T. & Yonetani, T. (1970) Adv. Biophys. 1, 157-182; Smith, D. W. & Williams, R. J. P. (1970) Struct. Bond. 7, 1-45; and Spiro, T. G. (1975) Biochim. Biophys. Acta 416, 169-189].
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230702
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 126
    Electronic Resource
    Electronic Resource
    Conversion from a virtual-bond chain to a complete polypeptide backbone chain (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1207-1224 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method for generating a complete polypeptide backbone structure from a set of Cα coordinates is presented. Initial trial values of φ and ψ for a selected residue are chosen (essentially from an identification of the conformational region of the virtual-bond backbone, e.g., and α-helical region), and values of φ and ψ for the remaining residues (both towards the N- and C-terminus) are then computed, subject to the constraint that the chain have the same virtual-bond angles and virtual-bond dihedral angles as the given set of Cα coordinates. The conversion from Cα coordinates to full backbone dihedral angles (φ,ψ) involves the solution of a set of algebraic equations relating the virtual-bond angles and virtual-bond dihedral angles to standard peptide geometry and backbone dihedral angles. The procedure has been tested successfully on Cα coordinates taken from standard-geometry full-atom structures of bovine pancreatic trypsin inhibitor (BPTI). Some difficulty was encountered with error-sensitive residues, but on the whole the backbone generation was successful. Application of the method to Cα coordinates for BPTI derived from simplified model calculations (involving nonstandard geometry) showed that such coordinates may be inconsistent with the requirement that φPro be near -75°. In such a case, i.e., for residues for which the algebraic method failed, a leastsquares minimizer was then used in conjunction with the algebraic method; the mean-square deviation of the calculated Cα coordinates from the given ones was minimized by varying the backbone dihedral angles. Thus, these inconsistencies were circumvented and a full backbone structure whose Cα coordinates had an rms deviation of 0.26 Å from the given set of Cα coordinates was obtained.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230706
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 127
    Electronic Resource
    Electronic Resource
    Conformation of P-form DNA (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1269-1281 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The P-Form of DNA has been studied by use of ir spectroscopy and electron microscopy (EM). The ir data show that the P-form has little or no hydrogen bonding, while the data from EM show that the P-form has a condensed tertiary structure. In earlier work, we demonstrated that the P-form is devoid of base stacking. When that information is combined with the new ir data, we conclude that the P-Form is denatured because it lacks any of the interactions associated with a normal secondary structure. This is in apparent contradiction to earlier work that showed that the P-form may be easily transformed back to a native state by adding water. However, the lack of secondary structure can be overcome by the presence of a collapsed tertiary state that does not allow non-hydrogen-bonded strands to separate. Thus, the complementary strands can renature quickly on addition of water. The collapse to a condensed tertiary structure occurs when roughly 90% of the charge on the DNA molecule is neutralized by counterion condensation, as calculated by the Manning polyelectrolyte theory, and is consistent with other collapsed DNA states in this respect. This structure explains all physical properties of the P-form that have been observed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230711
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 128
    Electronic Resource
    Electronic Resource
    The effects of alkali-metal chlorides and of spermidine and spermine on the swelling pressures of DNA gels in the ultracentrifuge (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1307-1313 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effects is solution of the alkali-metal chlorides on the gel-like phase of DNA formed in the ultracentrifuge cell have been studied. The polycations, spermidine and spermine, also were shown to affect strongly the swelling pressure of the DNA gel, with evidence for the destabilization of DNA in very dilute spermine, below 10-6 M, and for the collapse of DNA in both spermine and spermidine solutions above 10-6 M.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230714
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 129
    Electronic Resource
    Electronic Resource
    Effect of cationic surfactants on the conformation and aggregation of poly(L-glutamic acid) (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1333-1346 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effects of three cationic surfactants, dodecylammonium chloride (DAC), dodecyldimethylammonium chloride (DDAC), and dodecyldimethylammonium chloride (DTDAC), on the conformation of poly(L-glutamic acid) and at neutral pH were examined by CD. The maximum extent of the α-helix induction occurs for each surfactant when the mixing ration is about unity. Different effects specific to each surfactant, as described below, appear in the range of mixing ratios larger than that required for the maximum induction. In the case of DTAC, the α-helices disintegrate into random coils. In the case of DDAC, the aggregation of α-helices takes place eventually leading to precipitation. Solubilization of the precipitates occurs at high mixing ratios. The most complex behavior is seen in the case of DAC; aggregation of α-helices occurs only to a small extent and the formation of a small complex predominates over aggregation takes place again as DAC concentration increases further. Induction of the α-helix is favored by dilution at a constant mixing ratio but is suppressed by the addition of NaCl.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230717
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 130
    Electronic Resource
    Electronic Resource
    Locally oscillatory motion of RNA helix derived from linear relationships of backbone torsion angles (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1169-1184 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A linear relationship in each of the torsion angle pairs, α-β, β-∊, ∊-ζ, and α-γ, has been found by applying a statistical method based on the concept of circular variates to backbone torsion angle data of helical in yeast tTNAPhe. A series of helical dimer models generated with these relationships have been found to be stereochemically acceptable, and the models also indicate that the backbone unit in the RNA helix is geometrically capable of an oscillatory motion with the distance of about 3.4 Å between adjacent bases. The motion of the backbone unit is analogous to that of a helical spring. The adjacent bases, because of being attached to the backbone, oscillate in a manner similar to the oscillatory dimer model proposed by Davis and Tinoco [Davis, R. C. & Tinoco, I., Jr. (1968) Biopolymers 6, 223-242]. Here, the oscillation of the backbone unit in the RNA helix is discussed in terms of two geometrical quantities: the torsion (τ) and curvature (κ) of the helix. On these lines, a stereochemical model of RNA strand separation is proposed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230703
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 131
    Electronic Resource
    Electronic Resource
    The speed of sound in DNA (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1185-1192 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have used Brillouin scattering to determine the speed of sound in (and hence longitudinal modulus of) A- and B-DNA fibers. The speed of sound is very sensitive to the degree of hydration of the fibers, and measurements have to be made at laser powers below 5 mW to avoid local heating and dehydration. Under those conditions, we obtain sound speed perpendicular to the fiber axis of about 2.2 and 1.9 km/s in A- and B-DNA fibers, respectively. A-DNA fibers show a small anisotropy with sound speeds along the fiber axis higher by up to 10% B-DNA fibers appear to be isotropic.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230704
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 132
    Electronic Resource
    Electronic Resource
    Interaction of metal ions with gastrointestinal hormones: Binding studies of Mg++ to biologically active analogs of little gastrin and minigastrin (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1225-1240 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The interaction of magnesium ions with Des-Trp1-Nle12-minigastrin I (Nle11-HG-13) and Nle115-little gastrin I (Nle15-HG-17) has been studied by CD and spectrophotometric techniques in trifluoroethanol. Spectrophotometric titrations using murexide as a metallochromic indicator showed that there are three binding sites for magnesium ions in Nle11-HG-13, with binding constants of the order of (6 ± 2) × 106, (1.7 ± 0.5) × 106, and (5.0 ± 0.5) × 105M-1. These figures have been independently confirmed by CD measurements in the far-uv in the presence of increasing amounts of magnesium ions. Elongation of the peptide chain from Nle11-HG-13 to Nle15-HG-17 does not provide any additional binding site for the metal ions. In both hormones, we have observed different responses in the near- and fur-uv CD properties with regard to added magnesium. The intensity of the CD bands in the aromatic region changes cooperatively with the ion/hormone molar ratio. These findings lead us to conclude that at the C-terminal, the biologically important sequence, -Trp-Nle-Asp-Phe-Nh2, is directly involved in the interaction with magnesium.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230707
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 133
    Electronic Resource
    Electronic Resource
    Kinetics of irreversible dissociation for proteins bound cooperatively to DNA (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1249-1259 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We consider the irreversible dissociation kinetics of proteins that bind cooperatively and nonspecifically to DNA. Our model consists of an infinitely long one-dimensional nucleic acid lattice on which are bound protein ligands. A set of adjacent bound proteins forms a cluster of length n. A protein molecule may dissociate from any site within the bound cluster, not only from the ends, as was assumed in a previous model of this process due to Lohman [(1983) Biopolymers 22, 1697-1713]. By considering this additional pathway, we present a more general treatment of the dissociation kinetics of cooperatively bound ligands. We show that dissociation from the (n-2) internal positions of an n-cluster is an important pathway when the initial fractional saturation of the lattice is close to unity and the co operatively is low. When the fractional saturation is initially equal to 1 and the co operatively is low, our model does not give the zero-order dissociation kinetics predicted by the Lohman model.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230709
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 134
    Electronic Resource
    Electronic Resource
    Comments on the “ordinary-extraordinary phase transition” of poly(lysine) (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1637-1646 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The “ordinary-extraordinary phase transition” of poly(lysine), first reported by Lin et al. [(1978) Biopolymers 17, 1041-1064], has been reexamined as a function of the data collection interval (Δt) and scattering angle (θ). These data suggest that the relaxation domains “split” as the ionic strength is lowered through the transition region. In contrast, fluorescence photobleaching recovery data of Ware and coworkers (personal communication) indicate the tracer diffusion coefficient is not sensitive to the “ordinary-extraordinary phase transition.” The apparent discrepancy between these two techniques is here proposed to be due to small ion effects on both the dynamics and the scattering power of the polyelectrolytes.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230903
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 135
    Electronic Resource
    Electronic Resource
    Counterion binding and hydration of hyaluronate and chondroitin in solution: An 17O, 23Na, and 25Mg nuclear-magnetic-relaxation study (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1683-1699 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nuclear magnetic relaxation rates of H217O, 23Na+, and 25Mg2+ have been measured in aqueous hyaluronate solutions. The dependence on solution pH of the relaxation rates has been investigated, as well as the competition behavior of Na+ with Ca2+ and Mg2+. H217O and 23Na+ relaxation rates in chondroitin and hyaluronate solutions have been compared in the interval, 2 ≲ pH ≲ 12.5. The ion binding of hyaluronate can be fully accounted for by Coulomb interactions, with no need to involve chemical specificity. The hydration is only slighly pH dependent, and is comparable in magnitude to hydration of synthetic polyelectrolytes and monosaccharides. Ion-binding and hydration properties of hyaluronate and chondroitin are quite similar, except at elevated pH. At alkaline pH, an increase in charge density with pH is seen in hyaluronate and, to a much lesser degree, in chondroitin, possibly due to the titration of hydroxy groups. H217O data indicate an alkali-induced transition in both glycosaminoglycans.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230906
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 136
    Electronic Resource
    Electronic Resource
    Dielectric properties of slightly hydrated collagen: Time-water content superposition analysis (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1725-1734 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The frequency dependences of the dielectric constant, ε′, and the loss factor, ε″, in collagen were measured at several water contents from 0.1 to 0.3 g/g collagen over a frequency range of 30 Hz to 100 kHz and at a temperature of 20°C. Remarkable dispersion was observed at the lower frequencies for higher water contents. According to accumulated results on the thermodynamic and structural investigations, the dispersion has some analogy to the surface conduction proposed by B. V. Hamon [(1953) Aust. J. Phys. 6, 304-315]. An empirical relation bewteen ε″ and frequency, f, ε″ ∝ fn, where 0 〈 n 〈 1, suggests that the dielectric and conductive properties of hydrated collagen are related to carrier jumps between neighboring sites. For the polarization mechanism of this dispersion, we supposed a model of the transfer of protons between absorbed water molecules, and found that the time-water content superposition procedure is applicable to slightly hydrated collagen. The results derived from the superposition procedure show that the water content, φ, is related to the conductivity, σ, or the dielectric loss factor by the following equations: σ (φ, f) = const. × φnm-1f1-n and ε″ (φ, f) = const. φnmf-n, respectively, where m is a constant independent of φ and f. These results agree with that derived by another treatment of the same data. The role of water molecules in the conduction and polarization in slightly hydrated collagen is considered to be not far from that assumed in the model.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230908
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 137
    Electronic Resource
    Electronic Resource
    Thermodynamic stability of the ordered conformations of carrageenan polyelectrolytes (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1771-1794 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Manning's counterion condensation theory has been applied to the temperature-induced conformational transition of κ- and ι-carrageenan in the solution and gel states. The formalism of the theory has been extended to transitions between conformations with charge densities below or across the counterion condensation threshold. Measurements of the dependence of the melting temperature on ionic strength, and of the enthalpy of melting, are interpreted with the theory as indicating that the conformational transition is intramolecular and that side-by-side dimerization of chains gives rise to the gel structure.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230911
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 138
    Electronic Resource
    Electronic Resource
    Azobenzene-Containing polypeptides: Photoregulation of conformation in solution (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1423-1437 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photochromic polypeptides, with 16 to 56% azobenzene groups in the side chains, have been prepared by reaction of poly(L-glutamic acid) with p-aminozaobenzene, both in the presence of dicyclohexyl carbodiimide/N-hydroxybenzotriazole and of pivaloyl chloride. Analogous modification reactions carried out on poly(L-aspartic acid) were unsuccessful owing to the formation of N-succinimide rings. In trimethylphosphate, all the azopolypeptides exhibit the α-helix CD pattern. Irradiation produces the trans-to-cis isomerization of the azo side chains, but does not induce any variations of the backbone conformation. In water, the CD spectra indicate the presence of appreciable amounts of α helix in 16 and 21% mol azo-containing poly-(Lglutamates), while a β structure is present in a 36% mol azopolypeptide. Light produces conformational changes of the polypeptide conformation which are completely reversed in the dark. The extent and kind of photobehavior depend on the azo content and the pH value at which irradiation is carried out. The light-induced effects are discussed on the basis of the pH-induced order-disorder conformational transitions. In fact, the pK values and the transition curves of the dark-adapted samples were found to be different from those of the irradiated ones.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230723
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 139
    Electronic Resource
    Electronic Resource
    Vibrational circular dichroism of polypeptides. II. Solution amide II and deuteration results (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1519-1532 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Vibrational CD (VCD) of amide I and II vibrations of several α-helical polypeptides have been measured in solution. For the amide II as well as the amide I [previously published: Lal, B.B. & Nafie, L.A. (1982) Biopolymers 21, 2161] we find the VCD to be characteristic of the polypeptide secondary structure. Amide II bands of right-handed α helices were all found to have negative VCD and to have their maximum rotational strength for the parallel (low-energy) component. However, left-handed α helices formed from L-amino acids gave positive amide II bands at higher frequencies than found for the right-handed helices, indicating that the VCD was sensitive to the stereochemical difference. The amide-I VCD spectra of some deuterated right-handed α-helical polypeptides have a new negative feature to low frequency that does not reflect theoretical predictions but also appears to be stereochemically sensitive. Amide-II and amide-A VCD of a few deuterated polypeptides imply retention of the secondary-structure-dependent characteristics seen in the hydrogenated VCD.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230808
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 140
    Electronic Resource
    Electronic Resource
    Vibrational circular dichroism of polypeptides. III. Film studies of several α-helical and β-sheet polypeptides (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1533-1545 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Vibrational CD (VCD) of amides A, I, and II vibrations of a variety of polypeptide films have been measured. VCD of films of α-helical and β-sheet structures are compared in the three regions. Reproducible spectra could only be obtained for thin films free of orientation dependence. The sign and band shape of the VCD of films are not always the same as that in solution. However, the magnitude of the observed VCD seems to correlate with the secondary structure such that α-helical molecules typically have much larger Δε/ε values than do β-sheet molecules. The possibility of interference by artifacts owing to light-scattering effects is discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230809
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 141
    Electronic Resource
    Electronic Resource
    Masthead (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230901
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 142
    Electronic Resource
    Electronic Resource
    Structure determination of the adduct formed between the signal nucleotide diadenosine 5′, 5‴-P1, P4-tetraphosphate (Ap4A) and cis-[Pt(NH3)2Cl2] (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1623-1635 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Diadenosine 5′,5‴-P1,P4-tetraphosphate (Ap4A), an intracellular regulatory nucleotide, has been found to react with the antitumor drug cis-diamminedichloroplatinum(II) and its aqua derivative to form a single complex. This complex has been purified by high-performance liquid chromatography and characterized by 1H-nmr and CD spectroscopy. In this complex, Ap4A takes a very particular conformation. It is an N7-N7 chelate of the metal with the two adenines in a head-to-head arrangement and an anti-anti conformation of the adenosines. Platinum chelation leads to a large decrease of the Ap4A conformational flexibility.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230902
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 143
    Electronic Resource
    Electronic Resource
    Reversing-pulse electric birefringence of poly (γ-benzyl-L-glutamate). II. Field-strength dependence of steady-state and decay signals of well-fractionated samples (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1667-1681 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electric field dependence (up to 21 kV/cm) of the steady-state and decay signals has been examined on the four well-fractionated samples of poly(γ-benzyl-L-glutamate), [Glu(OBzl)]n, in N,N-dimethylformamide at 535 nm and 20°C. Together with the data previously obtained from the reversing-pulse electric birefringence [Ueda, K., Nomura, M. & Yamaoka, K. (1983) Biopolymers 22, 2077-2090], the steady-state birefringence and field-free relaxation time were analyzed by a method that takes into account the polydispersity of the chain length. The weight-average chain length, (lw), permanent dipole moment, (μw), electric polarizability anisotropy, (Δαw), and the length-independent optical anisotropy factor were evaluated. The axial translation per residue was calculated for the [Glu(OBzl)]n helix, but the uncertainly involved in the weight-average molecular weights, determined from light scattering by different investigators, makes the determination of the exact conformation of [Glu(OBzl)]n difficult. The contribution of Δαw to electric field orientation was found to be significant, since Δαw was approximately proportional to lw. A linear relationship also exists between μw and lw, when the [Glu(OBzl)]n helix is shorter than about 1200 Å.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230905
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 144
    Electronic Resource
    Electronic Resource
    Molecular theory of the helix-coil transition in polyamino acids. V. Explanation of the different conformational behavior of valine, isoleucine, and leucine in aqueous solution (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1961-1977 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Even though poly(L-valine) and poly(L-isoleucine) both contain residues that are branched at their β-carbon atoms, they exhibit a different behavior of their Zimm-Bragg helix-growth parameter s in aqueous solution. This quantity increases with temperature for poly(L-valine) but decreases for poly(L-isoleucine). The origin of this behavioral difference was examined by computing theoretical values of s versus temperature from interatomic interaction energies, taking solvent (hydrophobic and hydrophilic) effects into account. The calculated s versus temperature curves for both homopolymers are consistent with the observed experimental behavior. The two homopolymers behave differently because of differences in the change in the number of hydration-shell water molecules accompanying their helix-coil transitions. The larger isoleucine side chains are more crowded together in both the α-helical and coil forms than are those of valine. Therefore, there is a smaller change in hydration of the isoleucine side chains compared to that of the valine side chains in the helix-coil transition. By analyzing the effects of hydration on the s versus temperature curves, it is possible to account also for the experimental curve for poly(L-leucine), which exhibits an intermediate behavior between those for poly(L-valine) and poly(L-isoleucine).
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231012
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 145
    Electronic Resource
    Electronic Resource
    Vibrational analysis of peptides, polypeptides, and proteins. XXIV. Conformation of poly(α-aminoisobutyric acid) (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2025-2065 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Raman and polarized ir spectra have been obtained on built-up monomolecular films of poly(α-aminoisobutyric acid), and analyzed in the context of normal mode calculations on 310-, α-, and α′-helix conformations of this molecule. The average discrepancy between observed and calculated frequencies is significantly smaller for the 310-helix than for the other structures. This, together with the more satisfactory explanation of several special features of the spectra, indicates that this polypeptide adopts a 310-helix conformation in such thin films.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231016
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 146
    Electronic Resource
    Electronic Resource
    Resonance Raman spectra of mononucleotides obtained with 266 and 213 nm ultraviolet radiation (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2067-2081 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Resonance Raman spectra of the nucleoside 5′-monophosphates UMP, CMP, AMP, and GMP have been obtained with 266- and 213-nm radiation, the fourth and fifth harmonics of a Nd:YAG laser. The 266-nm radiation is resonant with the states giving rise to the first absorption band of the bases. The resulting spectra are in agreement with those reported previously using similar wavelength excitation but are generally of better quality. The 213-nm radiation is resonant with those states giving rise to the second strong absorption band of the bases. The spectra obtained with this wavelength show several new features relative to the 266-nm spectra, including strong enhancement of modes of the pyrimidines with a character similar to the e2g ν8 mode of benzene, relative enhancement of ring modes at 1580 and 729 cm-1 in AMP, and strong enhancement of the 1670-cm-1 C = O mode of GMP. These enhancements are discussed in terms of previously reported preresonance behavior and predicted intensities based on CNDO bond-order changes and normal-mode calculations. The results of a preliminary study of the effect of the interaction of GMP with cis-dichlorodiammineplatinum(II) on the 213-nm resonance Raman spectrum is also discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231017
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 147
    Electronic Resource
    Electronic Resource
    DNA gelation in concentrated solutions (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2141-2155 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sonicated calf-thymus DNA (200 ± 30 base pairs) spontaneously forms viscoelastic gels over a wide range of concentration, temperature, and buffer conditions. Quasielastic light scattering (QLS) can be used to monitor this process, because the ratio of dynamic-to-static scattering intensity decreases dramatically as gelation occurs. Using QLS, we have explored the effects of DNA concentration and mono- and divalent cations on the thermal stability of DNA gels. We found that the gel-sol transition temperature (Tgel) varies linearly with [DNA] from 7.5 to 17 mg/mL. Both Na+ and Mg2+ strongly stabilize the gel state. The sharpness of the transition increases with increasing ionic and DNA concentrations. Analysis of the Na+-dependent gelation indicates that the process requires the association of one Na+ per 118 base pairs. Mg2+ effectively stabilizes the gel at concentrations 10-fold below those required for Na+. The unexpectedly large effect of Mg2+ suggests that ion-specific interactions may play an important role in determining gel stability.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231104
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 148
    Electronic Resource
    Electronic Resource
    Large-amplitude bending motions in phenylalanine transfer RNA (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2173-2193 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformational energy calculations on yeast tRNAPhe reveal several likely modes of intramolecular bending, including both hingelike motions (rotations about a discrete point) and distributed flexibility (deformations that bend a double-helical segment along a smooth curve). By combining these modes of motion, the molecule can be bent from the L-shaped crystallographic structure to two extremes. It can be straightened into a nearly linear conformation at an energy cost of about 50 kcal/mol, and it can be doubled over to a conformation where the anticodon and the amino acid acceptor terminus are separated by about 40 Å at an energy cost of less than 100 kcal/mol. A bending range of over 100° can be covered for 50 kcal/mol, and we estimate that this value could be cut in half with a minimization algorithm that produced optimum stereochemistry. These energies are comparable to those that would be associated with changes in solvation due to changes in surface area as the molecule bends, indicating that there are no major steric barriers to tRNA flexibility and that variations in solvent conditions and interactions with other molecules may produce large changes in the overall conformation of tRNA.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231106
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 149
    Electronic Resource
    Electronic Resource
    Premelting and the hydrogen-exchange open state in synthetic RNA duplexes (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2099-2125 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Here we attempt to relate equilibrium temperature-dependent spectral changes in two synthetic RNA homopolymer duplexes - poly(rA) · poly(rU) and poly(rI) · poly(rC) - to the conformational opening detected in stopped-flow hydrogen-deuterium exchange experiments on these molecules. We are concerned with changes in several spectral properties that occur well below onset of the thermally induced helix-coil “melting” transition in these systems. These are known as “premelting” transitions, and can be detected in uv CD spectra as well as in vibrational bands of the bases in the ir. Both CD and ir spectra exhibit isoelliptic or isosbestic points consistent with a well-defined two-state premelting process. Application of a least-squares analysis to two-state models for premelting using data from different bands in the CD and ir shows that the enthalpies are substantially greater than that of the hydrogen-exchange opening. Thus the hydrogen-exchange open state represents only one premelting reaction among several that lead to equilibrium changes in helix geometry or base vibrational modes. The latter include processes that occur on a rapid time scale, including potential base-pair openings not productive for the exchange reaction. It appears that the former, and not the hydrogen-exchange opening, dominates the premelting alterations monitored by ir and CD spectroscopy.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231102
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 150
    Electronic Resource
    Electronic Resource
    Solvation effects on the 31P-nmr chemical shifts and infrared spectra of phosphate diesters (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2157-2172 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effects of organic solvents on the 31P-mr chemical shifts of various phosphate diesters have been investigated in water and mixed-organic solvent systems. The addition of organic solvents to cyclic phosphates and to diethyl phosphate causes large upfield shifts of the phosphorus resonance which are attributed to solvent-induced changes in the local hydration of the phosphodiester group. This is consistent with the fact that there is an inverse correlation between the hydrogen-bond-donating ability of the solvents and the magnitude of the shifts they induce. Other possible interpretations, such as solvent-induced ion pairing and solvent-induced conformational changes, appear to be eliminated. Fourier-transform ir study of the cyclic nucletides reveals that there are also large solvent-induced shifts in the frequency of the antisymmetric OPO stretching frequency, and a comparison of the two types of measurements indicates that there is a linear correlation between shifts observed in the ir and in the 31P-nmr spectra. With UpU, the solvent-induced 31P-nmr shifts are ∼3 times smaller than those observed with the cyclic phosphates and the solvent-induced shift of the OPO band is reduced (factor of ∼1.7) as compared with the cyclic phosphates. With the single-stranded polynuclotides, poly(C) and poly(U), the solvent-induced shifts in both the nmr and ir are quite small (∼0.1 ppm and ∼1 cm-1). The very small solvent effects observed with poly(U) and poly(C) are attributed to a combination of steric effects and a polyelectrolyte effect which maintains a high density of counterions with waters of hydration in the vicinity of the charged backbone and makes the phosphates much less susceptible to solvent-induced changes in hydration.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231105
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 151
    Electronic Resource
    Electronic Resource
    Conformation of cyclic analogs of enkephalin. II. Analogs containing a cystine bridge (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2325-2334 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A systematic survey has been made, using molecular mechanics, of the conformation of the ring entity of the enkephalin analogs, [D-Cys2-L-Cys5]-enkephalinamide and [D-Cys2-D-Cys5]enkephalinamide. These molecules are considerably more flexible than the analog Tyr-cyclo(Nγ-D-A2bu-Gly-Phe-Leu-), but the favored conformations of all three are very similar. The results of these studies are compatible with a Gly3-Phe4 type II′ bend in the active conformation of enkephalin.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231114
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 152
    Electronic Resource
    Electronic Resource
    Conformational transitions and geometry differences between low-energy conformers of N-acetyl-N′-methyl alanineamide: An ab initio study at the 4-21G level with gradient relaxed geometriesPaper 34 in the series “Ab Initio Studies of Structural Features Not Easily Amenable to Experiment.” (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2335-2347 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Energy pathways between the αR, β′, C7eq, and β-regions of the conformational energy surface of N-acetyl-N′-methylalanyl amide were obtained by SCF ab initio calculations on the 4-21G level, with gradient geometry optimization at each point. The calculations indicate that no barrier exists at this computational level between αR and β′. The variation of geometry (bond distances and bond angles) with conformation is analyzed in detail, and the most important geometrical parameters that should be treated as variables in both empirical energy calculations and in the fitting of polypeptide chains in proteins by x-ray methods are identified. In addition to the φ,ψ correlation discussed previously for the helical state, a correlation of these dihedral angles in the β-region is described.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231115
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 153
    Electronic Resource
    Electronic Resource
    Calorimetric study of 2U:1A three-stranded complexes formed between poly(U) and adenine dinucleotides: ApA and diastereoisomers of nonionic adenine dideoxyribonucleoside methyl phosphonate (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2361-2382 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Melting parameters of 2U:1A complexes formed by polyuridylic acid [poly(U)] and three adenine dinucleotides, diribonucleoside monophosphonate ApA and diastereoisomers of dideoxyribonucleoside methyl phosphonate [(dApA)1 and (dApA)2], in 1M NaCl and at a number of dinucleotide concentrations were obtained from differential scanning microcalorimetric data and interpreted in terms of the theory of helix-coil equilibrium in oligonucleotide-polynucleotide systems. The apparent binding constant, 1/cm, at 39°C and melting temperatures, Tm, at 1 × 10-3 M dinucleotide concentration indicate the following order of thermodynamic stability of the complexes: 2 poly(U) · (dApA)2 (2.27 × 103M-1, 44.2°C) 〉 2 poly(U) · (dApA)1 (9.9 × 102M1, 39.2°C) 〉 2 poly(U) · (ApA) (5.9 × 102M-1, 35.8°C). Corresponding calorimetric enthalpies of melting, ΔHm: 13.5, 12.7, and 12.8 kcal/mol (UUA base triplets) were found to be considerably lower than the van't Hoff enthalpies, ΔHapp: 29.4, 16.2, and 16.2 kcal/mol, respectively, evaluated from the dependence of the melting temperatures on dinucleotide concentration. Self-association of dinucleotides and their simultaneous binding as monomers, dimers, and higher-order associated species is suggested as the most probable cause of the differences between ΔHm and ΔHapp values. The differences in thermodynamic properties of the complexes formed by (dApA)1 and (dApA)2 diastereoisomers are discussed in connection with their known conformational properties. The higher and essentially enthalpic stability of the 2 poly(U) · (dApA)2 complex correlates with a lower degree of intramolecular stacking of the (dApA)2 isomer. The hydrophobically enhanced strong self-association of the latter greatly influences the thermodynamics of its complex formation with poly(U) and results in ΔHapp/ΔHm = 2.3.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231117
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 154
    Electronic Resource
    Electronic Resource
    Differential electrostatic stabilization of A-, B-, and Z-forms of DNA (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2743-2759 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The static accessibility discrete charge algorithm for protein charge interactions is extended to the case of linear polyelectrolytes. In this model, the effective dielectric value between surface charge sites depends predominantly on the solvent ionic strength and the solvent accessibilities of the charge sites. This treatment accounts for the phenomena of specific ion binding in the context of a general electrostatic effect [Matthew and Richards (1982) Biochemistry 21, 4989]. Specific ion sites are determined by locating areas of high electrostatic potential at the solvent interface of the macromolecule. At a given ionic strength the calculated potential at a site is taken to describe a binding constant and therefore the ion site occupancy. For a 20-base-pair fragment of B-DNA, net charge of -40, 16 ion sites are indicated in the minor groove. The partial occupancy of each site increases from 0.2 to 0.5 as the ionic strength is increased from 0.01 to 0.50. Over the same range of ionic strength, the electrostatic free energy of this charge array is calculated to change from +0.6 to -0.05 kcal/bp. Parallel behavior is predicted for A- and Z-DNA charge geometries. The most stable configuration, based on electrostatic criteria, at high ionic strength (I = 0.1-0.5) is that of Z-DNA. In this range, the ratio of “bound” sodium to phosphate is predicted to be less than 0.4.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231205
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 155
    Electronic Resource
    Electronic Resource
    Role of proline … proline interactions in the packing of collagenlike poly(tripeptide) triple helices (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2781-2799 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformational energy computations were carried out on the packing of two identical collagenlike poly(tripeptide) triple helices in order to determine the energetics of favorable packing arrangements as a function of composition and chain length. The triple helices considered were [CH3CO-(Gly-Pro-Pro)nt-NHCH3]3 and [CH3CO-(Gly-Pro-Ala)nt-NHCH3]3, with nt = 3, 4, and 5. The packing arrangements were characterized in terms of their intermolecular energies and orientation angles Ω0 of the axes of the two triple helices. For short triple helices (nt = 3 or 4), many low-energy orientations, with a wide range of values of Ω0, can occur. When the triple helices are longer (nt = 5), the only low-energy packing arrangements of two poly(Gly-Pro-Pro) triple helices are those with a nearly parallel orientation of the two helix axes, with Ω0 ≈ -10°. This result accounts for the observed parallel (rather than antiparallel) arrangement of collagen molecules in microfibril assembly and stands in contrast to the preferred antiparallel arrangement of a pair of α-helices. Since the preference for a parallel arrangement of these collagenlike triple helices is less pronounced in the case of poly(Gly-Pro-Ala), it appears that this preference is a consequence of the frequent presence of imino acids in position Y of the Gly-X-Y repeating triplet. In poly(Gly-Pro-Ala), most of the low-energy packing arrangements are parallel, but a few arrangements with low energies and high values of |Ω0| occur. These packing arrangements have a high energy, however, when Pro is substituted for Ala, and thus they are not accessible for collagen with natural amino (imino) acid sequences. The computations reported here account for some of the characteristic features of collagen packing in terms of the local interaction energies of a pair of triple helices.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231207
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 156
    Electronic Resource
    Electronic Resource
    Low-frequency dynamics of solid poly(L-alanine) from Raman spectroscopy (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2891-2899 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Raman modes from amorphous α-helical poly(L-alanine) in the low-frequency region 〈 150 cm-1 have been observed and assignments and values compared with mode-analysis calculations. The temperature dependence of the complete Raman spectrum of α-poly(L-Ala) is also reported.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231213
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 157
    Electronic Resource
    Electronic Resource
    A monte-carlo estimate of DNA loop formation (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 601-605 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ends of rather short double-helical DNA segments (approximately two persistence lengths) can be enzymatically joined to form closed circles. Such covalent closure into circles is a measure of the likelihood of the two ends of the DNA coming into close contact. There is a length of DNA for which loop formation is most likely to occur. We have determined the chain-length dependence of loop formation for stiff chains using computer-generated chains of cylinders. The distribution from which the values for the angles between cylinders were chosen relates the chain parameters to a given chain persistence. Our results are compared with those of other theories, including a statistical wormlike chain model, and with the experimental measurements for ring closure of DNA restriction fragments.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230313
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 158
    Electronic Resource
    Electronic Resource
    Masthead (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230401
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 159
    Electronic Resource
    Electronic Resource
    Intercalation of cationic dyes in the DNA double helix: Introductory theory (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 629-645 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of salt on the intercalation of acridine dyes and DNA is rather well explained by the Gouy-Chapman double-layer theory as applied to a cylinder model of the DNA-dye complex. The free energy of transfer of a dye ion from the bulk solution to the complex is divided into several parts, one of which, ΔF0, accounts for the short-range, nonelectrostatic interactions. The assumption that ΔF0 should not depend on the amount of dye in the complex leads to an internal dielectric constant of the cylinder of about Di = 7. The scatter in ΔF0 values, as calculated from individual experimental points, is of order 0.5 kT per dye ion. This scatter is large enough to mask possible effects of heterogeneity in DNA sequences. The calculations are made for a long cylinder with radius 10 Å, with the DNA phosphate charges smeared uniformly at the surface, a uniform spacing of dye charges at the cylinder axis, and a length of b = 3.37 Å per base pair. Each intercalated dye ion also adds a length b to the total length of the cylinder. The salt-dependent part of the electric free energy of intercalation, ΔF1, is tabulated for complexes with r = 0-0.24 dye ions per DNA phosphate in 0.002-0.2M monovalent salt and dye solutions.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230405
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 160
    Electronic Resource
    Electronic Resource
    Proton polarizability of poly(L-tyrosine)-hydrogen phosphate hydrogen bonds as a function of alkali cations (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 695-705 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We studied films of poly(L-tyrosine) with hydrogen phosphate (residue/phosphate, 1:1) by ir spectroscopy. The influences of the alkali cations (Li+, Na+, K+) and of the degree of hydration were clarified. If Li+ ions are present, the OH⃛-OP hydrogen bonds formed in the dried films between the tyrosine OH groups and hydrogen phosphate are asymmetrical. The formation of hydrogen phosphate-hydrogen phosphate hydrogen bonds is prevented by the presence of the Li+ ions. With an increase in the degree of hydration, the tyrosine-phosphate bonds are not broken but become slightly stronger. Completely different behaviour is found if K+ ions are present. In dry films, the OH⃛-OP ⇌ O-⃛HOP hydrogen bonds formed between tyrosine and hydrogen phosphate show large proton polarizability. The tyrosine proton has a noticeable residence time at the acceptor O atom of the phosphate. The difference in the behaviour of the system with K+ ions when compared to the system with Li+ ions can be explained, since the hydrogen acceptor O atom of phosphate ions is more negatively charged due to the weaker influence of the K+ ions. Furthermore, POH⃛-OP hydrogen bonds between hydrogen phosphate molecules are formed. With an increase in the degree of hydration, the tyrosine-hydrogen phosphate hydrogen bonds are broken, all tyrosine protons are found at the tyrosine residues, and the -PO3- groupings are in a symmetrical environment, indicating that the K+ ions are removed from these groupings. If the degree of hydration increases further, hydrogen-bonded systems such as hydrogen phosphate-water-hydrogen phosphate are formed that show large proton polarizability due to collective proton motion. When Na+ ions are present, the OH⃛-OP ⇌ O-⃛HOP hydrogen bonds formed in dry films still show proton polarizability, but the residence time of the tyrosine proton at the phosphate is very short.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230409
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 161
    Electronic Resource
    Electronic Resource
    Mechanism of gel formation in κ-carrageenan (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 735-745 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We present a general view of κ-carrageenan gelation and some new experimental results concerning their behavior in the presence of Na+, K+, or Rb+ counterions in semidilute concentration. The gelation mechanism is based on the aggregation of helical dimers.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230412
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 162
    Electronic Resource
    Electronic Resource
    Electronic structure of the PdCl42- and PtCl42-ions (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984), S. 201-209 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electronic spectra of PdCl42- and PtCl42- are studied by quantum-chemical methods with the ultimate object being to understand the differences in reactivity for Pt(II) and Pd(II) complexes. Nonrelativistic ab initio UHF, DV - Xα, and MSXα methods give very similar assignments of the spectra for PdCl42-. The d-d spectrum for PtCl42-, which is very different from the d-d spectrum of PdCl42-, agrees qualitatively with the spectra obtained using the relativistic extended-Hückel (REX) and Dirac-Slater (DS) methods. Although the latter two methods disagree somewhat in the interpretation of the high intensity bands in PtCl42-, it appears reasonable to interpret at least one of the lines as a 5d → 6p transition.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250116
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 163
    Electronic Resource
    Electronic Resource
    Spin-orbit excitation in the system I + I2: Relativistically parameterized extended-Hückel calculationsPresented at the Symposium on Relativistic Effects in Quantum Chemistry, Åbo Akademi, Finland, June 21-23, 1982. (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984), S. 223-231 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Relativistically parameterized extended-Hückel (REX) calculations concerning species and exchange reactions in the system I or I* + I2 are reported, where I = 2P3/2 and I* = 2P1/2. From their experimental data for related halogen systems X + YZ XY + Z, E. B. Gordon, A. I. Nadkhin, S. A. Sotnichenko, and I. A. Boriev [(Chem. Phys. Lett. 86, 209 (1982)] have proposed a conservation rule for the spin-orbit state (X* → Z*, X → Z). The results of REX calculations, double-group symmetry analysis, and schematic state correlation diagrams reported here are consistent with the proposed conservation rule. Two of the transition states are linear and the third nearly so, but no Γ1/2-Γ3/2 crossings leading to spin-orbit conversion are found.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250118
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 164
    Electronic Resource
    Electronic Resource
    Relativistic studies of atoms and ions with complex configurationsPresented at the Symposium on Relativistic Effects in Quantum Chemistry, Åbo Akademi, Finland, June 21-23, 1982. (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984), S. 47-55 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The method of the relativistic investigation of the energy spectra and the electronic transitions in the case of complex configurations, based on the theory of the irreducible tensorial operators and the genealogical coefficients, is described. The use of the quasispin and isospin technique in the relativistic approximation is discussed. Expressions are presented for electric multipole transition probabilities for general values of the gauge condition of electromagnetic field potential.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250105
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 165
    Electronic Resource
    Electronic Resource
    Relativistic atomic structure theory: Some recent workPresented at the symposium on Relativistic Effects in Quantum Chemistry, Åbo Akademi, Finland, June 21-23, 1982. (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984), S. 23-46 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Recent developments in relativistic atomic structure have been more in terms of program improvement than in fundamental theory. Some comments on both aspects of this work are illustrated by a description of two different recent applications. In the first, we study the contribution of the interaction of relativity and correlation to the 2 3S-2 3P0,1,2 intervals in heliumlike ions, whose theoretical estimation is important for testing QED. The study of satellite structure in the Kβ x-ray emission spectrum of Ar illustrates a quite different use of the program packages developed at Oxford for investigating configuration interaction. The use of shake theory to predict the initial states, populated along with the primary vacancy giving rise to the diagram line, gives a satellite line intensity distribution which agrees very well with recent experimental spectra.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250104
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 166
    Electronic Resource
    Electronic Resource
    Isospin basis for atoms in relativistic approximationPresented at the Symposium on Relativistic Effects in Quantum Chemistry, Åbo Akademi, Finland, June 21-23, 1982. (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984), S. 57-62 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The isospin basis is put into operation for investigation of atomic configurations, having two shells of equivalent electrons, characterized by the same orbital (LS coupling) or total (jj coupling) angular momenta of each electron. Tensorial properties of both the operators and the wave functions are studied in this basis. The two-particle operator is expressed in terms of the tensors irreducible in the isospin space. The problem of the additional classification of the levels is considered. The accuracy of the quantum numbers of the isospin basis in jj coupling scheme is discussed.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250106
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 167
    Electronic Resource
    Electronic Resource
    Use of the S-matrix in the relativistic treatment of resonance energy transfer (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984), S. 79-96 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The S-matrix formalism is used to treat the phenomenon of resonance energy transfer (sensitized fluorescence). It is shown that for dipole-allowed transitions and short sensitizer-acceptor separations, the relativistic treatment yields the same result as the nonrelativistic Perrin-Förster theory. For large sensitizer-acceptor separations, long-range coupling terms appear in the relativistic treatment. Resonance energy transfer through these long-range coupling terms is compared with spontaneous photon emission, and direct-interaction theories of electromagnetism are discussed. In the Appendix it is shown that the relativistic theory predicts resonance transfer of triplet excitation energy through the spin-spin coupling term in the Breit interaction.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250110
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 168
    Electronic Resource
    Electronic Resource
    Relativistic calculations of dissociation energies and related properties (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984), S. 131-148 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methods of calculation of potential energy curves or surfaces, including dissociation energies, bond distances, and vibration frequencies, are discussed as well as recently obtained results for several molecules. The ab initio relativistic methods involve the derivation of “shape-consistent” effective potentials from Dirac-Fock atomic calculations. These effective potentials are averaged and differenced with respect to spin with the differences, p3/2 - p1/2, etc., yielding spin-orbit operators. The molecular calculations are then set up in a familiar manner through the SCF stage using spin-averaged effective potentials. The final stage is a configuration-interaction calculation including the spin-orbit terms as well as the electron repulsion terms. Calculations that have been made for several low-lying excited states as well as the ground state for Au2, TlH, Tl2, Sn2, and Pb2 are reviewed. Good agreement is obtained with spectroscopic data and a number of interesting predictions are made.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250113
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 169
    Electronic Resource
    Electronic Resource
    Relativistic corrections to the valence and conduction band edges of anisotropic semiconductors (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984), S. 263-263 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250120
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 170
    Electronic Resource
    Electronic Resource
    Announcement. International academy of quantum molecular sciences (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984), S. 273-273 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250121
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 171
    Electronic Resource
    Electronic Resource
    Groups of simple graphsPresented at the symposium on “Applications of Group Theory and Graph Theory to Chemistry,” Southeast/Southwest Regional Meeting, American Chemical Society, 1980. (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984), S. 309-320 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The group structure of simple graphs can be found by factoring the adjacency matrix into cyclic blocks. The blocks correspond to permutational subgroups of the graph. The overall group structure is a product of the independent subgroups.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250204
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 172
    Electronic Resource
    Electronic Resource
    Calculation of localized molecular orbitals (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984), S. 355-365 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two techniques are presented for reducing the effort required to determine localized orbitals based on the energy or density criteria. The first, population weighted editing of the electronic repulsion integrals, reduces the effort required for each iteration of the localization procedure. The second, damping/extrapolation of the transformation matrix, reduces the number of iterations required to reach convergence. Numerical results are provided for methane and formaldehyde (for the editing method) and for carbon monoxide and boron fluoride (for the damping/extrapolation technique).
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250208
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 173
    Electronic Resource
    Electronic Resource
    Masthead (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984) 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250301
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 174
    Electronic Resource
    Electronic Resource
    Calculation of systems involving strong delocalized bonds within a modified PCILO framework. I. Valence-bond PCILO method (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984), S. 475-481 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In describing mesomer structures by the original PCILO method several problems may occur because of the use of localized bonds. A so-called VB-PCILO including a superposition of several mesomer boundary structures in the CI perturbation treatment will be proposed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250303
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 175
    Electronic Resource
    Electronic Resource
    Vibrational-rotational levels of diatomic RKR potentials (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984), S. 677-686 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The vibration-rotation levels for the diatomic RKR potential curve are solved using both perturbational and variational approaches. To obtain any-order correction of the energy from unperturbed parameters, an iterative scheme is formulated in the hypervirial framework. Variational calculations are carried out upon a rotationless Morse oscillator basis set and using a transformation technique to treat the effective potential energy function. Numerical results for the RbH X 1Σ+ state are obtained. The accuracy of the energy levels is tested by solving the Schrödinger equation by a numerical procedure.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250406
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 176
    Electronic Resource
    Electronic Resource
    Bonding in alkali metal homonuclear diatomics (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984), S. 723-731 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An analysis of the factors that contribute to the stability of the bond between alkali metal atoms is made by using nonorthogonal configuration interaction. Beyond the orbital size, the overlap of the valence orbitals of one atom with the core orbitals of the other accounts for most of the difference between the hydrogen molecule and the alkali metal diatomics. It is shown that the valence bond description does not provide a satisfactory description in any case except for the hydrogen molecule, and valence electron correlation using the p-type valence orbitals is essential.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250411
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 177
    Electronic Resource
    Electronic Resource
    Masthead (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984) 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250501
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 178
    Electronic Resource
    Electronic Resource
    Vibronic coupling of electronic states. IV. Harmonic CBO potentials with equal minima positions - the influence of different vibronic coupling strengths on the electronic absorption and emission spectra containing a longest-wavelength electronically forbidden transition (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984), S. 687-697 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The influence of vibronic coupling between two harmonic CBO potentials with equal minima positions on the electronic absorption and emission spectra is investigated in the framework of our model using the variational procedure. The numerical results, being identical with those obtained through the vibronic coupling model of Fulton, Gouterman, and Brickmann, are discussed with regard to the longest-wavelength electronically forbidden transition, its vibrational structure, and the Stokes loss.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250407
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 179
    Electronic Resource
    Electronic Resource
    Molecular orbital studies on the structure of nucleoside analogs. IV. Conformation of 3-deazapurine nucleosides (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984), S. 743-752 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformational properties of 3-deazapurine nucleosides (namely, 3-deazaadenosine and 3-deazaguanosine) have been investigated by the PCILO method. Both C(2′)-endo and C(3′)-endo sugar puckers have been considered and the results indicate that the conformational preferences of these nucleoside analogs are quite different from those of their parent nucleosides adenosine and guanosine, respectively. This result has been correlated in terms of the biological inactivity of these nucleoside analogs.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250413
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 180
    Electronic Resource
    Electronic Resource
    Convergence problems in SCF calculations: Further applications of a new technique based on the use of inverse Fock operator (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984), S. 809-816 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A recently proposed orbital optimization technique based on the use of the inverse of the level-shifted Fock operator is successfully applied to a large number of pathologically divergent cases. The possibility of eliminating convergence problems by adopting a similar modification in the operation of the orthogonal gradient method is also successfully tested.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250505
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 181
    Electronic Resource
    Electronic Resource
    The band structure of porphyrinatonickel(II). A semiempirical crystal orbital study based on the tight-binding formalism (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984), S. 817-851 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The band structure of porphyrinatonickel(II) (2) has been studied by means of crystal orbital calculations that are based on the tight-binding approximation; the computational framework is a recently developed INDO model for transition metal compounds of the 3d series. The porphyrinato polymer has been studied in an eclipsed arrangement (2a) and in a staggered conformation (2b) where neighboring layers are rotated by 41°. The total energy of the metallomacrocycle has been decomposed into one- and two-center contributions; the latter interaction parameters have been fragmented into physically feasible resonance, exchange, and classical electrostatic (electron-electron, electron-core, core-core) interactions. It is shown that individual two-center potentials between atoms in neighboring layers are prevailingly determined by the electrostatic interaction energy. The NiNi coupling in the chain is highly repulsive; important stabilizing interactions are predicted between the 3d center of one cell and the electronegative N atoms in the neighboring layers. Stabilizing and destabilizing electrostatic interaction potentials largely compensate each other; the net stabilization in the polymer comes from the accumulation of resonance and exchange increments. The unoxidized Ni(II) porphyrinato polymer is an insulator. Several ligand bands (π, σ, and lone-pair) are predicted on top of bands with significant Ni 3d admixtures; the conduction band of the unoxidized strand is of ligand π* character. The dense manifold of ligand states in the vicinity of the Ni 3d states (3dz2, 3dx2-y2, 3dxz/3dyz) prevents the formation of bands in the polymer that are strongly localized at the 3d center. Ni 3dz2 and 3dx2-y2 interact strongly with ligand lone-pair and σ states. Avoided crossings between ∊(k) curves in k space lead to compositions in the various bands that differ significantly at the bottom and the top. The INDO crystal orbital formalism predicts a partial oxidation of ligand bands in derivatives of 2 that contain oxidants (e.g., halides). The theoretical findings derived for 2 are compared with available experimental data on highly conducting porphyrinatonicke(II) polymers (tetrabenzo and octamethyltetrabenzo derivatives of 2).
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250506
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 182
    Electronic Resource
    Electronic Resource
    Masthead (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984) 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250601
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 183
    Electronic Resource
    Electronic Resource
    Calculation of bound-state energies from a variational functional method (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984), S. 1023-1033 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A variational functional method is improved and generalized in order to obtain approximate bound-state energies of a wide variety of quantum-mechanical systems. Calculations on the discrete spectrum of the hydrogen atom in a magnetic field and the bounded harmonic oscillator show that the procedure is very promising.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250607
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 184
    Electronic Resource
    Electronic Resource
    A modified PCILO framework using the CNDO/Boyd-Whitehead parametrization (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984), S. 1055-1060 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The CNDO/BW modification of the CNDO/2 approximation was used within the PCILO framework. It was shown on some significant examples that all the good results of the original PCILO-CNDO/2 method can be reproduced by the modified version PCILO-CNDO/BW at least. Thus, preserving the quality of its results a computer-expense-reduced PCILO method is proposed for calculations on large molecular systems.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250610
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 185
    Electronic Resource
    Electronic Resource
    Ab initio Hartree-Fock approach to the study of polymers: Application to polyacetylenes (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 26 (1984), S. 197-212 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An ab initio Hartree-Fock method devoted to the study of polymers is presented, truncation criteria for the exchange and the Coulomb series are discussed, and it is shown that the error in the total energy evaluation can be reduced to below 0.0001 a.u./cell with little computational effort. Results for six polyacetylene isomers are presented and compared with previous ab initio data obtained using the same basis set. In agreement with the experimental findings, the alternating all-trans structure is the most stable.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560260205
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 186
    Electronic Resource
    Electronic Resource
    Theoretical invstigations of the electronic states of porphyrins. I. Basis set development and predicted spectrum of pyrrole (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 26 (1984), S. 237-250 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new minimum basis set was developed for use in computing excitation energies of large molecules. It is particularly suited to calculating ionization potentials and Rydberg transitions. Pyrrole excitation energies and oscillator strengths calculated with this basis set are compared to larger basis set ab initio and semiempirical results. The 6-eV band in the experimental spectrum is predicted to be the result of three Rydberg absorptions, with no underlying (π, π*) absorption. The calculations also provide an explanation for the observed N—H stretch in the 6-eV region.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560260209
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 187
    Electronic Resource
    Electronic Resource
    Theoretical investigations of the electronic states of porphyrins. II. Normal and hyper phosphorus porphyrins (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 26 (1984), S. 251-274 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio methods have been used to calculate the ground and excited states of “normal” and “hyper” porphyrins. Perturbation theory and CI methods were used to determine differential ground and excited-state correlation effects for [Pv(P)F2]+ and [PIII(P)]+. A comparison is made to the INDO/S/CI predicted wavefunctions and spectra and to the experimental spectra of closely related molecules. The “hyper” [PIII(P)]+ calculations show some very low energy electronic transitions which provide an explanation for an anomalous “red” band in the spectrum and for the lack of fluorescence. Ab initio calculations also predict that (1) the lowest energy 1A1 state is a two-configuration wavefunction which can be described as a diradical, (2) the two lowest-energy singlet excited states are double excitations from the closed shell SCF configuration, and (3) a 3B2 state is very close in energy to the lowest 1A1 state.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560260210
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 188
    Electronic Resource
    Electronic Resource
    General harmonic oscillator integrals by the operator method (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 26 (1984), S. 339-347 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The operator technique with a minimum of commutator algebra is employed to calculate matrix elements of any number of operators between distorted, displaced harmonic oscillator wavefunctions. The results are valid for multidimensional integrals, and regardless of the extent of the Duschinsky effect. General recursion relations useful in machine calculations are given. The formalism is illustrated for the well-known one-dimensional Franck-Condon integrals.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560260304
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 189
    Electronic Resource
    Electronic Resource
    Localized molecular orbitals for multiple bonds in the ZDO approximation: The σ-π vs. banana bonds dilemma (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 26 (1984), S. 383-403 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The multiple bond description supplied by localized molecular orbitals obtained within the ZDO approximation is analyzed. In particular, conditions for the appearance of σ-π separation and of continuous degeneracy of the localization sum against σ-π mixing are given for two current ZDO energy- and density-localization methods. Likewise, a convenient modification of the latter is presented together with some illustrative examples.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560260307
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 190
    Electronic Resource
    Electronic Resource
    A unitary group formulation of many-body theory: Diagram systematics and use of the spin shifts (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 26 (1984), S. 125-143 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper shows that the spin-shift formalism developed in B. T. Pickup and A. Mukhopadhyay [Int. J. Quantum Chem. 26, 101 (1984)] supports a one-component diagrammatics which has a systematics akin to that in the spin-orbital many-body theory. The diagrams are neither Goldstone nor Yutsis type, and characterize the chain U(2R) ⊃ U(R)⊗SU(2) on which the spin-shift formalism is based. Accordingly, while the lines in such diagrams are labeled by the orbital indices, the diagram structure adequately reflects the irreducible representation of the group U(R). In this sense the paper presents a unitary group approach to the natural generalization of the usual many-body theory for the spin-adapted cases. A set of very simple rules is derived; their similarity with the corresponding rules in the ordinary many-body theory and practical utility are discussed in connection with (a) matrix elements over many-electron spin states and (b) closed- and open-shell many-body perturbation theory. A possibility of integral-driven many-body perturbation theory for open-shells is indicated. Connections of this formalism with others are also discussed.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560260109
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 191
    Electronic Resource
    Electronic Resource
    Electronic structure of the peptide linkage. I. Equilibrium geometry and electronic properties of formhydroxamic acid (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 26 (1984), S. 183-196 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The equilibrium geometry of formhydroxamic acid has been calculated within the framework of the INDO-MO formalism. Various structural factors are analyzed and discussed in terms of the calculated force constants and charge distribution. The possibility of internal rotation around the C—N bond of formhydroxamic acid has been examined. The potential energy surface for the amide-imide tautomerism is explored by calculating the geometries and characterizing saddle points on that surface. The cyclic and open dimers of formhydroxamic acid are examined and the hydrogenbond energy and length are calculated.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560260204
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 192
    Electronic Resource
    Electronic Resource
    Usage de l'algkbre de lie su(n) dans l'etude des systèmes quantiques à n etats. III. Définition et obtention des constantes du mouvement conjoncturelles (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 26 (1984), S. 479-488 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: From the density operator, some constants of the motion are defined and established. We suggest calling them conjunctural constants of the motion. It is proved that no more than n - 1 of them can be linearly independent. Using su(m) (m 〈 n ) subalgebra associated with the Hamiltonian-operator, it is shown how conjunctural constants of the motion can be expressed in terms of the coherence vector components.
    Notes: A partir de I'opérateur-densité d'un système quantique à n états, sont définies et calcultes des constantes du mouvement pour lesquelles est proposée I'appellation nouvelle de conjoncturelles. On établit qu'il en existe au maximum n - 1 linéairement indépendantes. A I'aide des sous-algèbres su(m) (m 〈 n ), on montre comment il est possible d'introduire, suivant la forme de I'hamiltonien, des constantes du mouvement conjoncturelles reliées aux composantes du vecteur de cohérence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560260406
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 193
    Electronic Resource
    Electronic Resource
    Masthead (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 26 (1984) 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560260501
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 194
    Electronic Resource
    Electronic Resource
    Theoretical approach of the chemical reactivity: The SN2 reaction (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 26 (1984), S. 593-605 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this survey paper the different possible theoretical ways of treating the SN2 reaction are explained. It is shown that, in the future, experience and theory will very likely complement each other.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560260504
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 195
    Electronic Resource
    Electronic Resource
    The concept of the chemical bond (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 26 (1984), S. 709-715 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The concept of the chemical bond is very old. Many interpretations have been proposed. Nevertheless, the problem is far from being solved. At the present time, the chemist has the choice between two models: the Lewis model (electron pairs) and the quantum model. In spite of a current opinion, both models are not logically equivalent. The localization of molecular orbitals is only a mathematical operation which does not involve any physic localization of the electrons. The loge theory is not more satisfying owing to the fact that loges with minimal fluctuation do not exist in all molecules. The theory of orbital domains seems to bring a solution. Nevertheless, its interpretation can be obtained only outside the strict framework of quantum mechanics.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560260510
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 196
    Electronic Resource
    Electronic Resource
    Convergence of LCAO density matrices in Hartree - Fock calculations on extended model chains (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 26 (1984), S. 717-723 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some mathematical implications of the extended nature of model chains are reviewed to call attention to their importance in electronic structure calculations at the restricted Hartree-Fock Roothaan level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560260511
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 197
    Electronic Resource
    Electronic Resource
    The effect of an impurity in quasi-one-dimensional systems: Green's function and cluster model approach in comparison (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 26 (1984), S. 753-768 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The problem of an impurity in a quasi-one-dimensional system is addressed. A hydrogen atom in a lithium chain serves as physical model. Two complementary descriptions, the cluster model approach with focus on local interactions, and the self-consistent Green's function approach which takes into account the extended nature of the system will be presented at the Hartree-Fock level. The results of both approaches are discussed in a comparative analysis.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560260515
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 198
    Electronic Resource
    Electronic Resource
    Quantum chemical studies on zeolites and silica (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 26 (1984), S. 793-822 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: After mentioning differences in C—O and Si—O bonding and different structural types of silicates, the conclusion that interactions between external partners and surfaces of silica and zeolites are mostly dominated by van der Waals forces is discussed. Consequently, the theoretical treatment includes (i) selection of appropriate cluster models, (ii) application of nonempirical quantum chemical methods for obtaining interaction potentials, and (iii) statistical thermodynamic evaluation of adsorption characteristics. As examples vibrational frequencies of H2O and NH3 adsorbed on cationic sites, the interaction of conjugated hydrocarbons with Na+ sites, and the interaction of H2O with various sites on silica and zeolite surfaces are considered.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560260519
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 199
    Electronic Resource
    Electronic Resource
    A review of a theoretical model of the excitonic superconductivity in CdS and CuCl (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 26 (1984), S. 831-841 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this review we briefly outline the model developed by Collins and co-workers [T. C. Collins, A. B. Kunz, and R. S. Weidman, Recent Advances in Quantum Theory of Polymers, J. M. Andre et al., Eds., Lecture Notes in Physics (Springer-Verlag, New York, 1979), Vol. 113, p. 240; T. C. Collins, M. Seel, J. J. Ladik, M. Chandrasekhar, and H. R. Chandrasekhar, Phys. Rev. B 27, 140 (1983)] for CdS and CuCl. The model should be applicable to organic semi-conductors. It is the outgrowth of the work of Little [W. A. Little, Phys. Rev. 134, 1416A (1964)], Devreese et al. [J. T. Devreese, A. B. Kunz, and T. C. Collins, Solid State Commun. 11, 673 (1972)] and a large amount of literature concerning He3 p-state [A. J. Leggett, Rev. Mod. Phys. 47, 331 (1975)]. This model is built around calculated band structures and the polarization of the valence band by conduction electrons at moderately high impurity concentrations. We extend the model to include both singlet and triplet paired spin states. The parallel paired states contribute a paramagnetic term to the susceptibility, and we discuss the conditions for this term to dominate over the diamagnetic term.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560260521
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 200
    Electronic Resource
    Electronic Resource
    Origin of high efficiency and specificity of biochemical reactions (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 26 (1984), S. 857-872 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is suggested that the extreme efficiency and specificity observed for chemical reactions in biological systems (compared to chemical reactions occurring under common chemical conditions) is mainly due to special features of these reactions. A key position is ascribed to the role of weak intermolecular interactions (also called noncovalent or van der Waals); in addition, the important role of the entropy and of cyclic or cavitylike shapes of numerous reaction sites, together with the influence of strong local electric fields on transport phenomena and reactivity are discussed. The greatest attention is paid to the applicability of computational methods for evaluation of weak intermolecular interactions, ranging from beyond Hartree - Fock methods to empirical potentials.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560260523
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...