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
  • 1
    Electronic Resource
    Electronic Resource
    The translational friction of toroids (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 1475-1489 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An approximate analytic expression for the translational friction coefficient of a toroid modeled as a continuous shell of frictional elements is derived using the Kirkwood approximation. The accuracy of this expression was determined by comparing the friction coefficients predicted by it to those predicted by extrapolated shell-model calculations using the modified Oseen tensor. To show that these calculations do indeed yield the correct friction coefficients, actual translational friction coefficients were determined by observing settling rates of macroscopic model rings or toroids in a high-viscosity silicone fluid. Our conclusion is that the approximate expression yields friction coefficients that are about 1.5-3% low for finite rings. For thin rings, a comparison is also made with the exact result of Yamakawa and Yamaki [J. Chem. Phys. 57, 1572 (1972); 58, 2049 (1973)] for the translational friction of plane polygonal rings. This comparison shows that the approximate expression yields results which are low by 2-3% unless the rings are extremely thin, in which case the error is larger. In the limit of an infinitely thin ring the approximate expression reduces to the Kirkwood result [J. Polym. Sci. 12, 1 (1954)], which is low by 8.3%. We discuss briefly how this work may be useful in determining the structure of DNA compacted by various solvent-electrolyte systems and polyamines.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190805
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Nearest-neighbor and next-nearest-neighbor effects in the proton NMR spectra of the oligoribonucleotides ApGpX and CpApX (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 557-573 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The variable-temperature proton nmr spectra of the oligoribonucleotides in the series CpApX and the series ApGpX, X = A, G, C, U, together with the parent dimers CpA and ApG have been measured. A complete analysis of all the nonexchangeable base proton resonances and ribose H-1′ proton resonances was made. The presence of trends in the shielding abilities of the various bases at both the nearest-neighbor and next-nearest-neighbor positions were identified. The observed shieldings could be used to predict the chemical shifts of protons in related systems. Based on the empirical results from ribodinucleoside monophosphates, the temperature-dependent behavior of the J1′2′ coupling constants of the triribonucleotides suggested that the compounds in the CpApX series stacked from the 5′-end to the 3′-end, while those in the ApGpX series stacked from the 3′-end to the 5′-end.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190309
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Twist, writhe, and geometry of a DNA loop containing equally spaced coplanar bends (1996)
    New York : Wiley-Blackwell
    Biopolymers 38 (1996), S. 235-250 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The formation of a topologically closed DNA loop is important in many biological processes, including the regulation of transcription, recombination, and replication. Modeling DNA as an isotropic elastic rod, we use finite element analysis to show that the dependence of the twist (ΔTw) and the writhe (Wr) upon the linking number deficit (ΔLk) is strongly influenced by intrinsic bends. We determine how the geometry of a DNA loop changes as a function of the number of uniformly spaced coplanar 20° bends, oriented so as to open toward the center of the loop. We also calculate the geometry of DNA rods that are smoothly bent to the same extent. The response of both ΔTw and Wr of a bent DNA to changes in ΔLk falls into one of three categories, depending upon the number of bends. For a single bend of 20°, Wr increases monotonically with ΔLk and the change in ΔTw with distance is constant along the entire DNA axis. For two to ten 20° bends, Wr passes first through a local maximum, then through a local minimum, and finally increases monotonically as ΔLk increases. For eleven to eighteen 20° bends, Wr again varies monotonically with ΔLk. For all numbers of bends greater than two, the ΔTw per unit length depends upon the distribution of intrinsic bends, being constant between any two adjoining bends but varying with their position relative to the cut location. Accompanying these ΔLk-associated changes in Wr and ΔTw per unit length are characteristic changes in geometry that are specific for each category. The results of these calculations raise the possibility that intrinsic bends can serve as a control factor in the biological functions associated with loop formation in DNA. © 1996 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 4
    Electronic Resource
    Electronic Resource
    Nearest-neighbor and next-nearest-neighbor effects in the proton NMR spectra of the oligoribonucleotides ApXpG, CpXpG, CpApXpUpG, ApGpXpC, and ApGpXpCpU (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 1383-1398 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The proton nmr spectra of the oligoribonucleotides in the series CpXpG, ApXpG, CpApXpUpG, and ApGpXpC (X = A, G, C, and U), together with the reference compounds CpG, ApG, CpApUpG, and ApGpC, have been measured. A complete analysis of all the nonexchangeable base protons and the ribose H-1′ protons was made. The insertion of a nucleotide X into a oligoribonucleotide led to shift changes at both nearest-neighbor and next-nearest-neighbor positions, which were rationalized in terms of the shielding abilities of the various bases. The derived shielding trends in the ApGpXpC series of compounds were successfully used to predict the chemical shifts of resonances in the related ApGpXpCpU series.
    Additional Material: 13 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200703
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Translational friction of rigid assemblies of spheres: Derivation and application of new hydrodynamic interaction tensors (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 1133-1143 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In connection with our goal of calculating by practical methods the frictional properties of biopolymers from surface shells composed of spheres, we have investigated by the method of reflections the low-Reynolds-number hydrodynamic interaction between two unequal-sized spheres in translation. Previous results, in which the velocities were used as independent variables and which have the form of truncated infinite power series, were substantially extended. By inversion of the power series, new power series with better convergence properties were obtained. Equivalence of these inverted power series with those previously reported based on the method of reflections, when forces are used as independent variables, was demonstrated, and the solutions were again substantially extended. Applying the Lagrange interpolation to data generated from exact theories for the hydrodynamic inteaction between two spheres, it was demonstrated that the various forms of the method of reflections do not just give reasonable power series, but actually yield optimal ones. These findings constitute a unification of diverse approaches and show methods of interconversion of results. On the basis of the power series obtained, a set of new hydrodynamic interaction tensors for two unequal spheres were derived. While the new tensors described the case of two unequal spheres with considerably more accuracy than those previously reported, direct application of these tensors to objects composed of more than two spheres revealed some unexpected problems resulting from overcorrection in the fourth-order term. However, when the tensors were preaveraged over all orientations of the multisphere object, a formula for the scalar translational friction coefficient was obtained that outperformed all but the most involved earlier approaches. It thus constitutes an improved and practical solution to the problem of computing translational friction coefficients of objects describable by a surface shell of many spheres, such as proteins.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220409
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Weak-link versus active carbon degradation routes in the oxidation of aromatic heterocyclic systems (1969)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Letters 7 (1969), S. 793-801 
    Details
    ISSN: 0449-2986
    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/pol.1969.110071108
    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...