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  • 1995-1999  (54)
  • 1985-1989  (133)
  • 1880-1889
  • 1996  (54)
  • 1987  (133)
  • Biochemistry
  • 1
    Electronic Resource
    Electronic Resource
    Control mechanisms of the behavior ‘secondary defense’ in the grasshopper Gomphocerus rufus L. (Gomphocerinae: Orthoptera) (1996)
    Springer
    Journal of comparative physiology 178 (1996), S. 329-336 
    Details
    ISSN: 1432-1351
    Keywords: Grasshopper ; Sexual behavior ; Spermatophore ; Accessory gland secretion ; Surgical ablations ; Biochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In the female grasshopper Gomphocerus rufus mating elicits ‘secondary defense’ which makes remating impossible. The behavioral change is caused by the liquid white secretions, proteins of less than 90 kD, which are produced by the white tubuli of the male's accessory glands. Experimental injection of the white secretions directly into the spermathecal duct of receptive virgins provokes ‘secondary defense’ instantly whereas sperm transfer had no such effect. ‘Secondary defense’ is also released by eggs entering the oviducts and excerting pressure against the oviductal walls on their way to oviposition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00193971
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  • 2
    Electronic Resource
    Electronic Resource
    The Solution Structure of the Immunodominant and Cell Receptor Binding Regions of Foot-and-mouth Disease Virus Serotype A, Variant A (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 75-90 
    Details
    ISSN: 1075-2617
    Keywords: FMDV ; structure ; NMR spectrocopy ; NEO constraints ; RGD (Arg-Gly-Asp) ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The solution structure of a 20 amino acid long peptide corresponding to the region 141-160 of the envelope protein Vp1 from foot-and-mouth disease virus (FMDV) serotype A, variant A, has been determined by a combination of NMR experiments and computer calculations. The peptide contains both the immunodominant epitope as well as the sequence (RGD) used by the virus to bind the cell receptor in the initial stages of infection. These two sites have been shown to partially overlap.One hundred and thirty-five NMR distance constraints were used to obtain a set of 11 structures by distance geometry, minimization and molecular dynamics simulations. These structures were divided into two homogeneous families based upon backbone superimposition. The first and most populated family was characterized by a backbone RMS of 1.5±0.4 Å, the second by a backbone RMS of 0.8±0.2 Å. The two families had similar structural features and differed mainly in the backbone angles of G149. In the larger of the two families these angles favoured the formation of a loop comprising residues 147 to 152 and stabilized by a H-bond between the NH of D147 and the CO of A152. In the second family, where this bond was absent, the peptide adopted in this region the shape of an irregular helix. The C-terminal half of the peptide (152-159) was similar in both families and largely helical. Similar structural features were also found within the VRGDS sequence (144-148) which was assigned to a β-turn type IV. The features of the two families of structures were found to be different from those of the recently published X-ray structure of the antigenic loop of a chemically modified form of FMDV. Proposals accounting for these differences are provided which take into account the dual activity of the 141-160 sequence (i.e. antibody binding and cell invasion through receptor binding).
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.49
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  • 3
    Electronic Resource
    Electronic Resource
    The Solution Conformational Features of Two Highly Homologous Antigenic Peptides of Foot-and-mouth Disease Virus Serotype A, Variants A and USA, Correlate with their Serological Properties (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 91-105 
    Details
    ISSN: 1075-2617
    Keywords: FMDV ; NMR spectrocopy ; RGD (Arg-Gly-Asp) ; NEO constraints ; structure-activity correlation ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The solution structure of a peptide corresponding to the VP1 region 141-160 of foot-and-mouth disease virus (FMDV) serotype A variant USA has been studied by NMR and computer calculations and compared with the results from a study on a highly homologous peptide deriving from serotype A, variant A. The two peptides differ in their serological behaviour and contain the immunodominant epitope of the virus which partly overlaps with its receptor binding region. Distance constraints, derived both from 2D and 3D homonuclear NMR and 2D-heteronuclear NMR experiments, were combined with DG calculations to yield 50 structures. After refinement through EM and restrained molecular dynamics simulations the selected structures shared several general features. In particular the 151-158 region was a helix in all cases while a large loop similar to that found in peptide A but comprising less residues and stabilized by an H-bond between the side chains of D147 and S150 was found in the majority of structures. A further loop, common to all structures, was identified around the RGD sequence (145-147). This was different from that found in the corresponding region of peptide A as were the conformations of the individual residues within the RGDX sequence.The different structural features shown by the two peptides were rationalized in terms of the S148 (peptide A) to F148 (peptide USA) mutation. The second mutation, that at position 153 (L in A, P in USA) did not appear to affect the structure of the peptide significantly although the different dimensions of the loop in the central region and the type of H-bond stabilizing it could be potentially ascribed to this second mutation.All criteria used pointed to different structural features for the two peptides consistent with their serological behaviour.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.50
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  • 4
    Electronic Resource
    Electronic Resource
    Solid-phase Synthesis and Cellular Localization of a C- and/or N-terminal Labelled Peptide (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 125-133 
    Details
    ISSN: 1075-2617
    Keywords: SPPS ; labelled peptides ; cellular localization ; amphipathic peptide ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We report the solid-phase synthesis by the Fmoc strategy of a peptide containing a cysteamide group at its C-terminus. This peptide was subject to further modifications including the linkage of fluorophores, namely lucifer yellow and coumarin respectively, at the C- and/or N-terminals. After incubation with living cultured cells these two probes were localized and it is concluded that the post-synthesis modifications can strongly modify the localization of the peptide.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.58
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  • 5
    Electronic Resource
    Electronic Resource
    Masthead (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996) 
    Details
    ISSN: 1075-2617
    Keywords: Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.310020201
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of End Group and Aggregation on Helix Conformation: Crystal Structure of Ac-(Aib-Val-Ala-Leu)2-Aib- OMe (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 106-116 
    Details
    ISSN: 1075-2617
    Keywords: all parallel helix assemblies ; helix transition ; 310-/Α-HELICES ; two conformers ; water associated with non-polar helices ; X-ray crystallography ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The role of end groups in determining stereochemistry and packing in hydrophobic helical peptides has been investigated using an α-aminosobutyric acid (Aib) containing model nonapeptide sequence. In contrast to the Boc-analogue, Ac-(Aib-Val-Ala-Leu)2-Aib-OMe crystallizes with two independent molecules in a triclinic cell. The cell parameters are: space group P1, a=10.100(2)Å, b=15.194(4) Å, c=19.948(5) Å, α=63.12(2)°, β=88.03(2)°, γ=88.61(2)°, Z=2, R=7.96% for 5140 data where |Fo|〉3σ(F). The two independent molecules alternate in infinite columns formed by head-to-tail hydrogen bonding. The helices in the two independent molecules are quite similar to each other but one molecule is rotated ≍123° about its helix axis with respect to the other. All the helical columns pack parallel to each other in the crystal. Replacement of the bulky Boc group does not lead to any major changes in conformation. Packing characteristics are also similar to those observed for similar helical peptides.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.52
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  • 7
    Electronic Resource
    Electronic Resource
    The Structures of the Frenatin Peptides from the Skin Secretion of the Giant Tree Frog Litoria Infrafrenata (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 117-124 
    Details
    ISSN: 1075-2617
    Keywords: peptides ; neuropeptide ; antimicrobial agent ; skin secretion ; frogs ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The granular dorsal glands of the giant tree frog Litoria infrafrenata contain five peptides including caerulein (a known neuropeptide), and four new peptides named frenatins 1 (MH+ = 1140 Da), 2 (1423), 3 (2180) and 4 (2493). The amino acid sequences of the frenatins are detailed: their structures do not correspond to those of peptides isolated from other amphibians or animals. Frenatin 3, Gly-Leu-Met-Ser-Val-Leu-Gly-His-Ala-Val-Gly-Asn-Val-Leu-Gly- Gly-Leu-Phe-Lys-Pro-Lys-Ser-(OH), has wide spectrum antimicrobial properties.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.60
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  • 8
    Electronic Resource
    Electronic Resource
    Structural Polymorphism of Gramicidin A Channels: Ion Conductivity and Spectral Studies (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 141-156 
    Details
    ISSN: 1075-2617
    Keywords: gramacidin A ; channel forming peptides ; Peptide conformational analysis ; cicular dichroism ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The relation between the various spatial structures of the gramicidin A channels and their ionic conductance has been studied. For this aim, various conformations of the peptide were pre-formed in liposomal bilayer and after subsequent fusion of liposomes with planar lipid bilayer the measured channel conductance was correlated with gramicidin structures established in liposomes. To form the single-stranded π6.3π 6.3 helix the peptide and lipid were co-dissolved in TFE prior to liposome preparation. THF and other solvents were used to form parallel (↑ ↑ π π) and antiparallel (↑ ↓ π π) double helices. Conformation of gramicidin in liposomes made by various phosphatidylcholines was monitored by CD spectroscopy, and computer analysis of the spectra obtained was performed. After fusion of gramicidin containing liposomes with planar bilayer membranes from asolectin, the histograms of single-channel conductance were obtained. The histograms had one or three distinct peaks depending on the liposome preparation. Assignment of the structure of the channel to conductance levels was made by correlation of CD data with conductance histograms. The channel-forming analogue, des(Trp-Leu)2-gramicidin A, has been studied by the same protocol. The channel conductances of gramicidin A and the shortened analogue increase in the following order: ↑ ↓ π π 2 ↑ ↑ π π 〈 π 6.3π6.3. Single-channels formed by double helices have higher dispersity of conductance than the π6.3π6.3 helical channel. Lifetimes of the double helical and the π6.3π6.3 helical channels are very close to each other. The data obtained were compared with theoretically predicted properties of double helices [1].
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.59
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  • 9
    Electronic Resource
    Electronic Resource
    A Combinatorial Peptide Library Around Variation of the Human Immunode ficiency Virus (HIV-1) V3 Domain Leads to Distinct T Helper Cell Responses (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 165-175 
    Details
    ISSN: 1075-2617
    Keywords: HIV ; peptide library ; immune response ; cytokines ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The hypervariable domain of the HIV gp120, the V3 loop domain, represents a target for neutralizing antibodies and for HIV vaccine strategies. In this study, we have investigated in murine species the potential cross-reactivity of immune responses elicited by immunization either with individual V3 peptides, derived from distinct HIV sequences (BRU, RF, SF2, MN and ELI sequences), or with a V3 combinatorial peptide library.We observed that individual V3 peptides are immunogenic but elicit a specific B- and T-cell immune response that is mainly restricted to the sequence of the immunizing peptide. In particular, T-cell responses that depend on T-cell receptor recognition of peptides bound to the molecules encoded by the major histocompatibility complex were significantly influenced by small differences in the peptide amino acid sequence. The combinatorial V3 peptide library, previously described as B- and T-cell immunogens, induced a more broadly reactive immune response, specially when T-cell cytokine secretion was used as a readout for restimulation of T-cells with individual V3 peptides.These data suggest that amino acid variations in the sequence of an antigenic peptide could lead to the induction of different transducing signals in the primed T-cell population and to the activation of T-cells with distinct cytokine secretion properties. These observations may have implications in the understanding of antigenic variability and in the design of vaccine strategies.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.54
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  • 10
    Electronic Resource
    Electronic Resource
    Synthesis of Fragments of the Peptide Component of Pseudobactin (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 157-164 
    Details
    ISSN: 1075-2617
    Keywords: sideropore ; peusdobactin ; peusdomycin ; solution-phase peptide synthesis ; unusual amino acids ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pseudobactin is a structurally complex and physiologically important siderophore (microbial iron chelator) from Pseudomonas putida- fluorescens. Various fragments of the unusual peptide component of pseudobactin listed below were prepared by solution-phase peptide synthesis.L-Lys· D-threo-β-OH Asp· L-Ala· D-allo-Thr· L-AlaL-Lys· D-threo-βOH Asp· L-Ala· D-allo-ThrD-threo-β-OH Asp· L-Ala· D- allo-Thr· L-Ala· D-N-OH-cycloOrnD-threo-β-OH-Asp· L-Ala· D-allo-Thr· L-AlaL-Ala· D-allo-Thr· L- Ala· D-N-OH-cycloOrnA class of related peptides named pseudomycins have shown promising antifungal activity. To examine if these peptide fragments above would elicit similar activity, the fragments were tested and found to have no antifungal activity in limited bioassays.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.61
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  • 11
    Electronic Resource
    Electronic Resource
    Masthead (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996) 
    Details
    ISSN: 1075-2617
    Keywords: Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.310020301
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  • 12
    Electronic Resource
    Electronic Resource
    The Importance of the Peptide Bond at Position 2 in HCO-Met-Leu-Phe-OMe Analogues as shown by Studies on Human Neutrophils (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 135-140 
    Details
    ISSN: 1075-2617
    Keywords: Nformylmethionyl peptides ; human neutrophils ; chemotaxis ; superoxide anion generation ; lysozyme release ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The formylpeptides formyl-methionyl-Nmethylleucyl- phenylaline methyl ester [for-Met-(NMe)Leu-Phe-OMe] 1, formyl-methionyl-2-aminotetralin-2-carboxyl-phenylalanine methyl ester [for-Met Act-Phe-OMe] 2, formyl-methionyl-1,2,3,4-terahydroisoquinoline-3-carboxl- phenylalanine methyl ester [for-Met-Tic-Phe-OMe] 3 and formyl- methionyl-2-aminoxy-4-methylvaleryl-phenylalanine methyl ester [for-Met-OLeu-Phe-OMe] 4 were synthesized in order to investigate the role of the amide bond at position 2 on biological activities on human neutrophils. Only analogue 2, which keeps the NH group at position 2, was found to retain activity though sterically encumbered.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.55
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  • 13
    Electronic Resource
    Electronic Resource
    Conformational Analysis of Neuropeptide Y Segments by CD, NMR Spectroscopy and Restrained Molecular Dynamics (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 176-193 
    Details
    ISSN: 1075-2617
    Keywords: NPY ; conformational analysis (CD, NMR) ; molecular dynamics ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Neuropeptide Y (NPY), a peptide amide comprising 36 residue has been shown to act as a potent vasoconstrictor. In order to shed light on the structural requirements for the biological activities with respect to the different prerequisites for affinity to the NPY receptor subtypes Y1 and Y2, in the present study the syntheses and conformational analyses of two C-terminal segments, NPY(18-36) and NPY(13-36), are described.The results obtained by CD measurements, two-dimensional NMR spectros copy and a conformational refinement of the NMR-derived structure by molecular mechanics simulations support the findings of previously published structure -activity relationship studies for biologically active and selective compounds. In particular, the α-helical conformation as well as an appropriate exposure of the side chains of the critical C-terminal dipeptide within NPY(18-36) are in agreement with the prerequisites proposed for Y2 receptor binding of that segment.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.62
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  • 14
    Electronic Resource
    Electronic Resource
    Hydrophobic Effects on Antibacterial and Channel-forming Properties of Cecropin A-Melittin Hybrids (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 223-232 
    Details
    ISSN: 1075-2617
    Keywords: antimicrobial peptides ; hydrophobic residue ; ion-channels ; pores ; α-helix ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The design of cecropin-melittin hybrid analogues is of interest due to the similarities in the structure of the antimicrobial peptides cecropin and melittin but differences in their lytic properties. We suspected that a hydrophobic residue in position 2 of milittin (Ile8 in the hybrid) plays an important role in the activity of the 15-residue hybrid, KWKLFKKIGAVLKVL-NH2, [CA(1-7)M(2-9)NH2] and have now examined its role in the analogue toward five test bacteria. Deletion of Ile8 reduced activity, and it was not restored by lengthening to 15 residues by addition of another threonine at the C-terminus. Replacement of Ile8 by a hydrophobic leucine maintained good activity and Ala8 was equally active for four organisms, although less active against Staphylococcus aureus. Replacement by the hydrophilic Ser8 strongly reduced potency against all five organisms. Deletion of Leu15 decreased activity, but addition of Thr16 maintained good activity. The presence of hydrophobic residues appears to have a significant effect on the process of antibacterial activity. These peptide analogues showed voltage-dependent conductance changes and are capable of forming ion-pores in planar lipid bilayers. The antibacterial action of the peptides is thought to be first an ionic interaction with the anionic phosphate groups of the membrane followed by interaction with the hydrocarbon core of the membrane and subsequent reorientation into amphipathic α-helical peptides that form pores (ion-channels), which span the membrane. The analogue also showed an increase in α-helicity with an increase in hexafluoro 2-propanol concentration.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.63
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  • 15
    Electronic Resource
    Electronic Resource
    The Use of Proton Chemical Shifts to Define the Solution Structure of a Dimeric Peptide (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 233-239 
    Details
    ISSN: 1075-2617
    Keywords: NMR ; chemical shift estimation ; restrained refinement ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: For flexible peptides, nuclear Overhauser Effects (NOE) experiments do not provide enough information to ensure a correct definition of their solution structure. The use of distance constraints, derived from the knowledge of proton chemical shifts, is developed to restrict the number of possible conformations. In the case of flexible molecules, randomization appears as an important factor of the correct estimation of the chemical shifts from the 3D structure. The refinement of the solution structure of the highly flexible AVP-like parallel dimer is described to illustrate this process.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.67
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  • 16
    Electronic Resource
    Electronic Resource
    Multiple Column Synthesis of a Library of T-Cell Stimulating Tn-Antigenic Glycopeptide Analogues for the Molecular Characterization of T-Cell-Glycan Specificity (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 212-222 
    Details
    ISSN: 1075-2617
    Keywords: mucin glycopeptides ; tumour associated antigen ; cancer ; MHC Class II binding ; glycopeptide synthesis ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of peptides and glycopeptides derived by amino acid and glycosyl amino acid scans through the self peptide from CBA/J mouse haemoglobin Hb (67-76), VITAFNEGLK, was synthesized by multiple column peptide synthesis (MCPS). Investigation of glycopeptide binding to the mouse major histocompatibility class II molecule Ek showed that glycans in position 72 did not interfere with the binding to Ek. Immunization experiments revealed that glycopeptides with the glycan in position 72 were immunogenic. Therefore a series of N-linked and O-linked glycopeptides with the glycan attached in the position 72 either to serine, threonine or asparagine was synthesized by MCPS. The glycan structure was furthermore varied with respect to monosacc haride component, size of oligosaccharide, anomer configuration and stereoche mistry of essential hydroxyl groups in order to investigate the specificity of the interaction with the T-cell receptor. Easy synthesis of ready to use Ser and Thr building blocks corresponding to mucin core 1, the Tn-antigen and its β-anomer were developed using trichloroacetimidates as glycosyl donors and reduction with in situ acetylation of the azide containing glycosylation products. Synthesis of an α-linked GlcNAc-Thr building block was achieved by glycosylation of Fmoc-Thr-OPfp with 2-azido-2-deoxy-3,4,6-tri-O-acetyl-D- glycopyranosyl trichloroacetimidate as a glycosyl donor. Other building blocks were obtained by previously described procedures.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.64
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  • 17
    Electronic Resource
    Electronic Resource
    Current Concepts in Intestinal Peptide Absorption (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 195-211 
    Details
    ISSN: 1075-2617
    Keywords: peptide absorption ; dipeptide carrier ; brush border membrane ; M-cell, Caco-2 cell ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Today there is considerable interest in oral peptide delivery. However, oral administration of peptides is limited by a low bioavailability and a high variability in plasma levels. A review is given of the literature describing the major barriers in peptide absorption, the basic mechanisms of intestinal peptide transport, the experimental models and the pharmaceutical approaches currently used in the investigation of peptide and protein absorption processes.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.66
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  • 18
    Electronic Resource
    Electronic Resource
    Immunogenicity Studies with Haptenated Melittin Peptides: Implication for Membrane Involvement during the Recognition Step (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 252-260 
    Details
    ISSN: 1075-2617
    Keywords: melittin immunogenicity ; antigen recognition ; membrane involvement ; haptenic position ; late IgG responses ; cellular dynamics ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Melittin peptides carrying 2,4-dinitro-6-carboxyphenyl (Dncp) haptenic groups regularly evoked anti-hapten IgG responses in mice or guinea pigs when the hapten was C-terminally attached. Single haptens on the N-terminal helix in several positions gave poor or no responses in the early stages but adequate titres after prolonged immunization. Peptides with Dncp at the C-terminus as an invariant feature and a second Dncp in various positions along the peptide chain did not fail to produce adequate responses. The hampering effect is not due to a defect at the T-cell level but involves the recognition step on the B-cell. It is implied that the haptenic interaction with the paratope of the recognizing immunoglob ulin on the B-cell involves the cell membrane in an important way. It is also suggested that late antibody responses should not be overlooked during the development of proteinaceous immunogens for vaccination.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.74
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  • 19
    Electronic Resource
    Electronic Resource
    Backbone Cyclization of the C-terminal Part of Substance P. Part 1: The Important Role of the Sulphur in Position 11 (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 261-269 
    Details
    ISSN: 1075-2617
    Keywords: substance P ; agonist ; conformational constraint ; backbone cyclization ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Novel backbone-to-side chain and backbone-to-backbone cyclic analogues of substance P (SP) were prepared by solid-phase synthesis and screened for biological activity. An analogue containing a thioether- lactam ring between positions 9 and 11 showed an EC50 value of 20nM toward the neurokinin 1 (NK-1) and was inactive toward the NK-2 and NK-3 receptors. On the other hand, in a multiple backbone cyclic peptide library of similar analogues, in which the sulphur was excluded from the ring, very low activity was detected. The activity was re-evaluated and was found to be even lower (EC50=0.11 mM) than the previously published data. These results indicate that the thioether moiety has a crucial role in receptor activation. The results also show tolerance of the NK-1 receptor, but not NK-2 or NK-3, to cyclization of the C-terminal portion of the SP6-11 hexapeptide.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.76
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    Electronic Resource
    Electronic Resource
    Multivalent Ligand System Carrying Enkephalin and Neurotensin Coimmobilized on Liposomes (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 245-251 
    Details
    ISSN: 1075-2617
    Keywords: enkephalin ; neurotensin ; opioid receptor affinity ; multivalent ligand ; liposome ; fluorescence microscopy ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A multivalent ligand system was constructed by coimmobilization of two kinds of peptide ligands, enkephalin and neurotensin derivatives having a dioctadecyl group, on dimyristoylphosphatidylcholine (DMPC) liposomes. The enkephalin derivatives are Tyr-D-Ala-Gly-Trp-Leu- (Sar-Sar-Pro)n-[N(C18H37)2] (Enk3nD, n=0, 1, 2), where a dioctadecyl group was connected to the C-terminal side of enkephalin directly or through a hydrophilic and flexible spacer chain of different lengths. The neurotensin derivatives are Ac-Glu[N(C18H37)2]-(Sar-Sar-Pro)n-Arg-Arg-Pro-Tyr-Ile-Leu-OH (D3nNT, n=0, 1, 2, 3). The derivatives were spontaneously immobilized on DMPC liposomes by overnight incubation. The receptor affinity of the enkephalin derivatives became significantly higher upon immobilization on liposomes. The highest affinity was obtained for the δ receptor by Enk6D immobilized on DMPC liposomes. This affinity is higher than that of enkephalinamide. Neurotensin derivatives coimmobilized with large amounts of Enk3D on DMPC liposomes show higher affinity than the neurotensin derivatives immobilized alone. The effect of Enk3D on the receptor affinity of the coimmobilized neurotensin derivative disappeared by the addition of [Ala2, MePhe4, Gly-ol5]enkephalin (DAGO). Therefore, the receptor affinity of a peptide hormone is altered by immobilization on DMPC liposomes and by coimmobilization with other peptide hormones. It was confirmed by fluorescent microscopy that the multivalent ligand system binds to receptors without release of the bound ligands from DMPC liposomes.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/psc.73
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    Electronic Resource
    Electronic Resource
    Masthead (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996) 
    Details
    ISSN: 1075-2617
    Keywords: Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.310020401
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  • 22
    Electronic Resource
    Electronic Resource
    Cysteine Racemization in Peptide Synthesis: A New and Easy Detection Method (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 271-275 
    Details
    ISSN: 1075-2617
    Keywords: peptide synthesis ; cysteine ; racemization ; enantiomeric resolution ; capillary electrophoresis ; gas chromatography ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new method has been developed for the rapid determination of D-cysteine contents in synthetic peptides. It is based on the reduction of cystine residues, when present, with tris- alkylphosphines, selective derivatization of the cysteine residues with 4-vinylpyridine, followed by acid hydrolysis of the (4-pyridylethyl)cysteine -peptides. Baseline enantiomeric resolution of theD,L-S-β-(4-pyridylethyl)cysteine, and thus quantification ofD- enantiomer contents at levels ≤1%, is easily achieved by capillary zone electrophoresis exploiting the host-guest complexation principle with crown ethers or by gas chromatography on chiral glass capillary columns upon conventional derivatization of the hydrolysate. The acid-stability of the (4-pyridylethyl)cysteine derivative prevents racemization via thiazoline intermediates and allows for standardization of the acid hydrolysis-dependent racemization.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.83
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    Electronic Resource
    Electronic Resource
    12th International symposium on affinity interactions: Fundamentals and applications of biomolecular recognition (1996)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 9 (1996), S. 258-258 
    Details
    ISSN: 0952-3499
    Keywords: Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmr.300090302
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  • 24
    Electronic Resource
    Electronic Resource
    Masthead (1996)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 9 (1996) 
    Details
    ISSN: 0952-3499
    Keywords: Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmr.300090501
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  • 25
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    Electronic Resource
    Christian B. Anfinsen (1916-1995). Words devoted to his memory at the 11th Affinity Chromatography Meeting, San Antonio, Texas - May 1995 (1996)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 9 (1996), S. 752-752 
    Details
    ISSN: 0952-3499
    Keywords: Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmr.300090502
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  • 26
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    Electronic Resource
    Molecular recognition in drug discovery. A special issue based on the 36th Annual Buffalo Medicinal Chemistry Symposium (1996)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 9 (1996), S. 53-53 
    Details
    ISSN: 0952-3499
    Keywords: Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmr.300090202
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  • 27
    Electronic Resource
    Electronic Resource
    Masthead (1996)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 9 (1996) 
    Details
    ISSN: 0952-3499
    Keywords: Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmr.300090301
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  • 28
    Electronic Resource
    Electronic Resource
    Masthead (1996)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 9 (1996) 
    Details
    ISSN: 0952-3499
    Keywords: Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmr.300090101
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  • 29
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    Electronic Resource
    Erratum (1996)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 9 (1996), S. 52-52 
    Details
    ISSN: 0952-3499
    Keywords: Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmr.300090102
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  • 30
    Electronic Resource
    Electronic Resource
    Masthead (1996)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 9 (1996) 
    Details
    ISSN: 0952-3499
    Keywords: Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmr.300090401
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  • 31
    Electronic Resource
    Electronic Resource
    Masthead (1996)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 9 (1996) 
    Details
    ISSN: 0952-3499
    Keywords: Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmr.300090201
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  • 32
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    Solution synthesis of human midkine, a novel heparin-binding neurotrophic factor consisting of 121 amino acid residues with five disulphide bonds (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 28-39 
    Details
    ISSN: 1075-2617
    Keywords: Solution synthesis ; human midkine ; powerful solvent system ; powerful solvent system ; active region ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Human midkine (hMK), a novel heparin-binding neurotrophic factor consisting of 121 amino acid residues with five intramolecular disulphide bonds, was synthesized by solution procedure in order to demonstrate the usefulness of our newly developed solvent system, a mixture of dichloromethane or chloroform and trifluoroethanol. The final protected 121-residue peptide was assembled from two large fully protected intermediates, Boc-(1-5 9)-OH and H-(60-121)-OBzl, in CHL/TFE (3:1, v/v) using water-soluble carbodiimide in the presence of HOOBt as coupling reagents. After removal of the protecting groups by HF followed by treatment with Hg(OAc)2 in 50% acetic acid, the fully deprotected peptide was subjected to the oxidative folding reaction. The final product was confirmed to have the correct disulphide structure from its tryptic peptide mapping and to possess the same biological activities as those of the natural product. In order to clarify the active region of the hMK molecule, the N-terminal and C-terminal half domains [(1-59) and (60-121)] were also synthesized by the same procedure used for the hMK synthesis. The C-half domain was confirmed to show the full pattern of bioactivities except for the neuronal cell survival activity, while the N-half one showed much less activity in general.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.45
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  • 33
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    310-Helices, Helix Screw Sense and Screw Sense Reversal in the Dehydro-peptide Boc-Val-ΔPhe-Gly-ΔPhe-Val-OMe (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 47-58 
    Details
    ISSN: 1075-2617
    Keywords: Dehydro-peptides 310-helix ; helix reversal ; crystal structure ; circular dichroism ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pentapeptide Boc-Val-ΔPhe-Gly-ΔPhe-Val-OMe, containing two dehydro-phenylalanine (ΔPhe) residues, has been synthesized and its structure investigated. In the crystalline state, the molecule adopts a right-handed 310-helical conformation stabilized by two intramolecular hydrogen bonds between CO of Val1 and NH of ΔPhe4, and between CO of ΔPhe2 and NH of Val5, respectively. NMR measurements are consistent with the presence of 310-helical structures also in acetonitrile and dimethylsulphoxide solution: the distances between backbone protons estimated from NOE connectivities are in overall agreement with those observed in the solid state; the chemical shifts of the amide protons show the smaller temperature coefficients for the NHs that in solid state are involved in intramolecular hydrogen bonds. The CD spectra in acetonitrile, chloroform, methanol and dimethylsulphoxide display exciton couplets of bands corresponding to the ΔPhe electronic transition at 280nm; the sign of the bands is consistent with the presence of helical structures having a prevalent left-handed screw sense. Addition of 1,1,1,3,3,3-hexafluoro- propan-2-ol gives rise to the gradual appearance of a couplet of opposite sign, suggesting the helix reversal from left-handed sense to right-handed sense. The conformational behaviour is discussed on the basis of the specific sequence of the peptide.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.47
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  • 34
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    δ-Selective Opioid Peptides Containing a Single Aromatic Residue in the Message Domain: An NMR Conformational Analysis (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 290-308 
    Details
    ISSN: 1075-2617
    Keywords: opioid peptides ; selectivity ; antagonism ; conformation ; NMR ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The sequence of deltorphin I, a δ-selective opioid agonist, has been systematically modified by inserting conformationally constrained Cα,α disubstituted apolar residues in the third position. As expected, substitution of Phe with Ac6c, Ac5c and Ac3c yields analogues with decreasing but sizeable affinity. Surprisingly, substitution with Aib yields an analogue with almost the same binding affinity of the parent compound but with a greatly increased selectivity. This is the first case of a potent and very selective opioid peptide containing a single aromatic residue in the message domain, that is, only Tyr1. Here we report a detailed conformational analysis of [Aib3]deltorphin I and [Ac6c3]deltorphin I in DMSO at room temperature and in a DMSO/water cryomixture at low temperature, based on NMR spectroscopy and energy calculations. The peptides are highly structured in both solvents, as indicated by the exceptional finding of a nearly zero temperature coefficient of Val5 NH resonance. NMR data cannot be explained on the basis of a single structure but it was possible to interpret all NMR data on the basis of a few structural families. The conformational averaging was analysed by means of an original computer program that yields qualitative and quantitative composition of the mixture. Comparison of the preferred solution conformations with two rigid δ-selective agonists shows that the shapes of [Aib3]deltorphin I and [Ac6c3]deltorphin I are consistent with those of rigid agonists and that the message domain of opioid peptides can be defined only in conformational terms.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.56
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  • 35
    Electronic Resource
    Electronic Resource
    Solid-phase Synthesis of ω-Agatoxin IVA, a P-type Calcium Channel Blocker (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 309-317 
    Details
    ISSN: 1075-2617
    Keywords: solid-phase synthesis ; calcium channel blocker ; spider toxins ; side reaction ; peptide folding ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ω-Agatoxin IVA, isolated from the venom of funnel web spider Agelenopsis aperta, blocks potently and selectively P-type calcium channels. This toxin, composed of 48 amino acids and containing 8 cysteine residues, was synthesized by the solid-phase procedure. The Cys residues were protected by acetamidomethyl (Acm) groups which were removed by mercuric acetate. During treatment with mercuric acetate, a by-product was detected, involving modification of tryptophan residues by the Acm groups. This side reaction can be completely prevented by addition of an excess of tryptophan in the reaction medium during Acm deprotection.The resulting peptide was submitted to an oxidative refolding, in different conditions, in order to determine the most favourable protocol. After formation of the four disulphide bonds, the toxin was purified by successive preparative HPLC, on two different supports, and fully characterized by analytical HPLC, capillary electrophoresis, amino acid analysis, mass spectrometry and Edman degradation. It was found to block the P-type calcium channel with a similar biological potency as described for the natural product.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.57
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  • 36
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    Preferred conformation of peptides rich in Ac8c, a medium-ring alicyclic Cα,α-disubstituted glycine (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 14-27 
    Details
    ISSN: 1075-2617
    Keywords: β-bend ; cyclic amino acid ; 310-helix ; peptide conformation ; X-ray diffraction ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A complete series of terminally blocked, monodispersed homo-oligopeptides (to the pentamer level) from the sterically demanding, medium-ring alicyclic Cα,α-disubstituted glycine 1-aminocyclooctane-1-carb oxylic acid (Ac8c), and two Ala/Ac8c tripeptides, were synthesized by solution methods and fully characterized. The preferred conformation of all the oligopeptides was determined in deuterochloroform solution by IR absorption and 1H-NMR. The molecular structures of the amino acid derivative Z-Ac8c-OH, the dipeptide pBrBz- (Ac8c)2-OH and the tripeptide pBrBz-(Ac8c)3-OtBu were assessed in the crystal state by X-ray diffraction. Conformational energy computations were performed on the monopeptide Ac-Ac8c-NHMe. Taken together, the results obtained strongly support the view that the Ac8c residue is an effective β-turn and helix former. A comparison is also made with the conformational preferences of α-aminoisobutyric acid, the prototype of Cα, α-disubstituted glycines, and of the other members of the family of 1-aminocycloalkane-1-carboxylic acids (Acnc, with n=3, 5-7) investigated so far. The implications for the use of the Ac8c residue in peptide conformational design are considered.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.43
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  • 37
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    Elucidation of the structure of constrained bicyclopeptides in solution by two-dimensional cross-relaxation spectroscopy: Amatoxin analogues (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 3-13 
    Details
    ISSN: 1075-2617
    Keywords: Structure of amatoxin analogues ; constrained bicyclopeptides ; NMR ; molecular dynamics ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The evaluation of peptide structures in solution is made feasible by the combined use of two-dimensional NMR in the laboratory (NOESY) and rotating frames (ROESY), and by the use of molecular dynamics calculations. The present paper describes how both the NMR method and molecular dynamics calculations were applied to very rigid synthetic bicyclic peptides that are analogues of natural amatoxins. The NMR theory, which allows the estimate of interatomic distances between interacting nuclei, is briefly discussed. The experimental data were compared with those of known solid-state structures. Three amatoxin analogues have been examined. Of these, one is biologically active (S-deoxo γ[R] OH-Ile3-amaninamide) and its structure in the solid state has recently been worked out. The second and third analogues (S-deoxo-Ile3 -Ala5-amaninamide and S-deoxo-D-Ile3 -amaninamide, respectively) are inactive and their solid-state structures are unknown. The data presented confirm the authors' previous hypothesis that lack of biological activity of S-deoxo-Ile3-Ala5- amaninamide is due to the masking of the tryptophan ring by the methyl group of L-Ala and not to massive conformational changes of the analogue.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.44
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  • 38
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    The Total Chemical Synthesis of Monocyte Chemotactic Protein-1 (MCP-1) (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 40-46 
    Details
    ISSN: 1075-2617
    Keywords: Tetrabenzo[a,c,g,i]fluorenyl-17-methoxycarbonyl ; Tbfmoc ; peptide synthesis ; solid-phase synthesis ; MCP-1 ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The affinity-based Nα-amino protecting group tetrabenzo [a,c,g,i]fluorenyl-17-methoxycarbonyl (Tbfmoc) has been utilized as a hydrophobic probe to allow the simple, quick and highly effective isolation of a 76 residue cysteine-containing protein (MCP-1). The base-labile Tbfmoc group can be removed under very mild conditions, which preserve the thiol-con taining protein in the reduced state. Oxidative folding was then used to furnish the biologically active β-chemokine MCP-1.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.46
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  • 39
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    Crystal Structure and Molecular Conformation of the Cyclic Hexapeptide cyclo-(Gly-Aib-Gly)2 (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 59-65 
    Details
    ISSN: 1075-2617
    Keywords: Aminoisobutyric acid ; glycine ; cyclic peptides ; X-ray diffraction ; β-turns ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have synthesized and crystallized the cyclic peptide (Gly-Aib-Gly) 2. Its structure has been determined by conventional X-ray diffracti on methods. In the crystal it adopts a conformation with one β-turn (type I) and its mirror image at the other side of the ring. All conformation al angles are similar to those reported for these amino acid residues. In particular the Aib residue has a conformation intermediate between α- and 310-helical conformations. The ring is an adequate model for the β-turn conformation. A molecule of formic acid is found in the crystal which shows a very short hydrogen bond with one of the glycine carbonyl groups.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.48
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  • 40
    Electronic Resource
    Electronic Resource
    Inclusion volume solid-phase synthesis (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 240-244 
    Details
    ISSN: 1075-2617
    Keywords: solid-phase synthesis ; peptide synthesis ; multiple synthesis ; inclusion volume synthesis ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Solid-phase synthesis of peptides was carried out using only the volume of the solvent included in the swollen solid-phase resin beads [inclusion volume synthesis]. This approach enables (i) the use of higher concentrations of activated amino acids, resulting in increased coupling rates, (ii) drastically decreased consumption of solvents, and (iii) the construction of multiple peptide synthesizers having virtually no reaction vessels.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.310020402
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  • 41
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    Editorial (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 1-1 
    Details
    ISSN: 1075-2617
    Keywords: Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.53
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  • 42
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    Masthead (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996) 
    Details
    ISSN: 1075-2617
    Keywords: Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.310020101
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  • 43
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    Synthesis of a New Template with a Built-in Adjuvant and Its Use in Constructing Peptide Vaccine Candidates Through Polyoxime Chemistry (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 66-72 
    Details
    ISSN: 1075-2617
    Keywords: MAPS ; Pam3Cys ; polyoxime ; polypeptide vaccine ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthetic lipopeptides are showing promise as vaccine candidates, but until now it has been very difficult to prepare them in homogeneous form. We describe the synthesis and characterization of a new water-soluble, four-branched template with a built-in lipophilic adjuvant (Pam3Cys). Through the use of oxime chemistry, we attached four copies of an unprotected influenza virus peptide and characterized the product (13kDa) by reversed-phase HPLC and electrospray ionization mass spectrometry. Several other such constructions were made using the new template and different peptides. We seem to have a general method for making synthetic lipopeptides in homogeneous form.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.51
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  • 44
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    Nonconventional Protease Catalysis in Frozen Aqueous Solutions (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 279-289 
    Details
    ISSN: 1075-2617
    Keywords: peptide synthesis ; frozen aqueous solution ; protease ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: During the past decade proteases have been widely used as catalysts in peptide synthesis. Unfortunately, they are not ideal ligases. Enzymatic peptide synthesis in frozen aqueous systems has been developed as an approach towards the suppression of competitive reactions. This paper summarizes reports concerning the behaviour of non-enzymatic as well as of enzyme-catalysed reactions when the reaction mixture is frozen. The advantages of freezing the reaction mixture in serine and cysteine protease-catalysed peptide synthesis, the influence of modified reaction conditions and the possible reasons for the yield-increasing effect of freezing are discussed.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/psc.65
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    The Immunomodulatory Activity of Peptides Related to the DNA Contacting Loop of p53 Protein (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 318-324 
    Details
    ISSN: 1075-2617
    Keywords: p53 protein ; peptide immunomodulators ; TP5 analogues ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Taking into account the sequence homology existing between thymopoietin II and the DNA-binding domain of p53 protein, a series of octapeptides was synthesized, related to the wild p53 type protein as well as to its mutated forms, appearing in some human tumours. The wild type octapeptide has immunostimulative activity with regard to the humoral immune response, but is inactive in the cellular immune response. The mutated peptides of p53 differ in their immunomodulatory activity from the wild type octapeptide. The Ser5 analogue of the wild type peptide is a strong stimulant of the humoral immune response and enhances TNF-α production, while at the same time suppressing the cellular immune response. The data suggest that the mutations of p53, which favour tumour development and growth, may also change the immune activity of respective p53 fragments.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.68
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  • 46
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    An Exploration of the Effects of Constraints on the Phosphorylation of Synthetic Protein Tyrosine Kinase Peptide Substrates (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 325-338 
    Details
    ISSN: 1075-2617
    Keywords: conformational constraints ; CD spectroscopy ; fluorescence quenching ; synthetic peptides ; tyrosine phosphorylation ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We synthesized by classical solution methods three conformational constrained analogues of EDNEYTA, a heptapeptide sequence that represents the common major autophosphorylation site of the protein tyrosine kinases (PTKs) of the Src family. The correlation between the different structural properties induced by the modifications of the native sequence and the propensity of the peptides to act as PTK substrates was examined. The kinetic data obtained indicate that the introduction of the tyrosine-analogue constraints Tic(OH) and MeTyr, which block the ring flexibility, completely prevents the phosphorylation catalysed by the kinases Lyn and Fgr. On the other hand PTKIIB/p38syk can phosphorylate the two derivatives albeit with an efficiency lower than that found with the native sequence. A third derivative contained side chain to side chain cyclization. This analogue, in which the freedom of the phenolic moiety is not altered, can be phosphorylated by all the PTKs tested with kinetic constants comparable to the parent peptide.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.70
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  • 47
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    Masthead (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996) 
    Details
    ISSN: 1075-2617
    Keywords: Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.310020501
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  • 48
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    Solution Conformation of [D-Pen2,D-Pen5]enkephalin in Water: A NMR and Molecular Dynamics Study (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 351-356 
    Details
    ISSN: 1075-2617
    Keywords: DPDPE ; enkephalins ; NMR structure analysis ; molecular dynamics simulations ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The solution conformation of [D-Pen2,D-Pen5] enkephalin (DPDPE), a highly potent δ-selective opioid agonist, was examined by means of NMR, molecular mechanics and molecular dynamics methods. The structural information in the solvent water was obtained employing one- and two-dimensional methods of 1H and 13C-NMR spectroscopy. Based on the distance geometry technique using the ROE data as input, 400 conformers were obtained and considered in the structure analysis. Alternatively, about 2000 conformers were stochastically generated and related to the NMR data after energy minimization. The structure analysis provides one conformer in agreement with all NMR data, which belongs to the lowest energy conformation group. This structure may serve as a reference conformer for DPDPE analogues synthesized with the aim of activity increase.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.71
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  • 49
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    Preparation of Site-Specific Isotopically Labelled Zervamicins, the Antibiotic Peptaibols Produced by Emericellopsis Salmosynnemata (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 341-350 
    Details
    ISSN: 1075-2617
    Keywords: Biosynthesis ; deuterium ; nitrogen 15 ; positive ion FAB mass spectrometry ; ion channel-forming peptide ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A simple procedure for the preparation of the specifically labelled peptide antibiotic zervamicins IC, IIA and IIB has been developed. The zervamicin molecules are labelled with stable isotopes by culturing the Emericellopsis salmosynnemata on a well-defined synthetic medium containing the highly isotopically enriched amino acid. To obtain the peptide with the specifically and highly enriched amino acid residue, precautions have been taken to prevent any de novo biosynthesis of the particular amino acid from unlabelled precursors. The enrichment of the labelled peptide is determined by mass spectrometric analysis. Following this method we have incorporated [2′,4′, 5′,6′,7′-2H5]-L-Trp-1, [1′-15N]-L-Trp-1 and [2′, 3′,4′,5′,6′-2H5]-L- Phl-16 into zervamicins IC, IIA and IIB on the preparative scale and without scrambling of the label. Thus, using the procedures described, isotopically labelled zervamicins can be prepared, allowing them to be studied by solid- state NMR.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/psc.72
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  • 50
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    Towards the Understanding of the Folding of Methylene Units in the Glutamine Residue (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 364-370 
    Details
    ISSN: 1075-2617
    Keywords: conformation ; glutamine ; folding ; simulation ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational preferences of the methylenic sequence in the side chain of the glutamine residue were investigated by ab initio and semi-empirical quantum mechanical calculations and examination of both the Brookhaven Protein Databank and Cambridge Structural Data Base. The results were analysed on the basis of our previous findings about the folding of methylene groups in aliphatic segments. Both energy calculations and the crystallographic structure of small peptides indicate that methylene units of the glutamine residue tend to fold in a gauche conformation. In contrast, such groups usually adopt an all-trans conformation in proteins due basically to the entropic and solvent contributions. These results have been demonstrated by computing the entropic correction to the free energy and evaluating the solvent effects through SCRF calculations
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.75
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  • 51
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    Masthead (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996) 
    Details
    ISSN: 1075-2617
    Keywords: Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.310020601
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  • 52
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    Folded Structures in Protonated Reduced Dipeptides (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 381-391 
    Details
    ISSN: 1075-2617
    Keywords: conformational analysis ; crystal structure ; folded structures ; pseudopeptides ; reduced peptides ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reduced dipeptides with the general formula RCO-Xaa- rXbb-N+HR′R′′ (rXbb, reduced analogue of residue Xbb: NH-Cα HR1 -Cr H2) are shown to adopt a folded conformation in solution and in the solid state. The protonated reduced amide bond is an active proton donor capable of interacting with a peptide carbonyl to give a strong hydrogen bond topologically equivalent to the i+2 or i+3⇒ i interaction. The resulting conformation is similar to the γ- or β-turn structure found in peptides and proteins.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/psc.78
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    The Use of Crown Ethers in Peptide Chemistry - V. Solid-phase Synthesis of Peptides by the Fragment Condensation Approach using Crown Ethers as Non-covalent Protecting Groups (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 371-380 
    Details
    ISSN: 1075-2617
    Keywords: crown ether ; fragment condensation ; peptide synthesis ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have previously described the conditions by which peptide synthesis by the solid-phase fragment condensation approach can be carried out using crown ethers as non-covalent protection for the Nα -amino group. Here we demonstrate that the procedure can be extended to large, partially protected peptide fragments possessing free Lys and/or Arg residues. The first step was to ensure that complex formation on the side chain of amino acids was not detrimental to the methodology and exhibited the same solubility and coupling properties as Nα -complexed peptides. Thus, a model hexapeptide was synthesized using Fmoc chemistry containing Lys and Arg residues, which, when complexed with 18-Crown-6, was readily soluble in DCM and coupled quantitatively to a resin-bound tetrapeptide. Two tripeptides were then prepared, one containing a free Ser residue, the other free Tyr, to examine the possible occurrence of side reactions. After coupling using standard conditions only the former tripeptide exhibited the formation of the O-acylation by-product (5%). Another model hexapeptide containing Lys, Tyr, Ser and Asp protected with a TFA-stable adamantyl group was complexed with 18-Crown-6 and coupled to the resin-bound tetrapeptide with near quantative yield. Extending the length of the peptide to 21 and 40 residues, which represent sequences Gly52 to Leu72 (21-mer) and Pro33 to Leu72 (40-mer) from Rattus norvegicus chaperonin 10 protein, respectively, resulted in partially protected fragments that were readily soluble in water, thus enabling purification by RP-HPLC. Complexation with 18-Crown-6 gave two highly soluble products that coupled to resin-board tetramer with 68% and 50% coupling efficiencies for the 21-mer and 40-mer, respectively. Treatment with 1% DIEA solutions followed by acidolytic cleavage and purification of the major product confirmed that the correct product had been formed, when analysed by amino acid analysis and ESI-MS. These results served to extend the methodology of non-covalent protection of large partially protected peptide fragments for the stepwise fragment condensation of polypeptides.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/psc.79
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    Design of Peptides Using α,β-Dehydro-residues: Synthesis, Crystal Structure and Molecular Conformation of N-Boc-L-Val-ΔPhe-ΔPhe-L-Ala-OCH3 (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 357-363 
    Details
    ISSN: 1075-2617
    Keywords: β-turns ; folded conformation ; dehydro-residue ; X-ray diffraction ; consecutive dehydro-residue ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: To obtain general rules of peptide design using α,β-dehydro-residues, a sequence with two consecutive ΔPhe-residues, Boc-L-Val-ΔPhe-ΔPhe- L-Ala-OCH3, was synthesized by azlactone method in solution phase. The peptide was crystallized from its solution in an acetone/water mixture (70:30) in space group P61 with a=b=14.912(3)  Å, c= 25.548(5)  Å, V=4912.0(6)  Å3. The structure was determined by direct methods and refined by a full matrix least-squares procedure to an R value of 0.079 for 2891 observed [I≥3σ(I)] reflections. The backbone torsion angles φ1=-54(1)°, ψ1= 129(1)°, ω1=-177(1)°, φ2 =57(1)°, ψ2=15(1)°, ω2 =-170(1)°, φ3=80(1)°, ψ3 =7(2)°, ω3=-177(1)°, φ4 =-108(1)° and ψT4=-34 (1)° suggest that the peptide adopts a folded conformation with two overlapping β-turns of types II and III′. These turns are stabilized by two intramolecular hydrogen bonds between the CO of the Boc group and the NH of ΔPhe3 and the CO of Val1 and the NH of Ala4. The torsion angles of ΔPhe2 and ΔPhe3 side chains are similar and indicate that the two ΔPhe residues are essentially planar. The folded molecules form head-to- tail intermolecular hydrogen bonds giving rise to continuous helical columns which run parallel to the c-axis. This structure established the formation of two β-turns of types II and III′ respectively for sequences containing two consecutive ΔPhe residues at (i+2) and (i+3) positions with a branched β-carbon residue at one end of the tetrapeptide.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/psc.77
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    Experimental toxicology of formaldehyde (1987)
    Springer
    Journal of cancer research and clinical oncology 113 (1987), S. 305-309 
    Details
    ISSN: 1432-1335
    Keywords: Formaldehyde ; Mutagenicity ; Metabolism ; Biochemistry ; Carcinogenicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Formaldehyde is a reactive chemical which undergoes spontaneous reactions with various cellular constituents. Mutagenicity data may be interpreted on the background of this behavior. Mice are better able to reduce the irritating effect of formaldehyde than rats and to reduce their ventilation rate when formaldehyde acts on the respiratory tract. Subacute exposure of rats to concentrations higher than 2 ppm inhibits mucociliary clearance of the nasal epithelium and leads to progressive histological and ultrastructural lesions at this site. The occurrence of squamous cell carcinomas of the nasal epithelium of rats after 2 years inhalation of 14.3 ppm formaldehyde (CIIT study) is probably the result of chronic and recurrent local toxicity; this is supported by species differences in susceptibility to the tissue damaging and carcinogenic effect of formaldehyde (rat, mouse, hamster). Data on formaldehyde-DNA interaction further support the argument that a direct risk extrapolation from the formaldehyde effects in rats to those expected for man is not possible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397713
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    Myoadenylate deaminase deficiency: absence of correlation with exercise intolerance in 452 muscle biopsies (1987)
    Springer
    Journal of neurology 234 (1987), S. 385-389 
    Details
    ISSN: 1432-1459
    Keywords: Myoadenylate deaminase ; Histochemistry ; Biochemistry ; Neuromuscular diseases ; Exertional myalgia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A histochemical assay was routinely performed of myoadenylate deaminase (MAD) in muscle biopsy specimens. MAD was absent in 13 cases, i.e. 2.9% of the specimens. In 10 cases the deficiency was confirmed biochemically. The diagnoses in the 13 patients were: polyneuropathy (n=5), infantile spinal muscular atrophy (n=3), congenital myopathy with type 2 fibre atrophy, facioscapulohumeral myopathy, polymyositis, myotonic dystrophy and hyperornithinaemia with gyrate atrophy of the retina. In contrast, 35 unrelated patients presenting with exercise-related muscle cramps or pains showed normal histochemical MAD activity. The biopsy specimens in all of these patients were essentially normal and in none of them was the diagnosis of a neuromuscular disease made. The results failed to confirm the association of MAD deficiency with aches, cramps and pains or exertional myalgia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314082
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    Computer enumeration and generation of physical trees (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 549-554 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A computer-oriented method for the enumeration and generation of physical trees is presented. Physical trees depict acyclic chemical structures, but the term physical is used to stress the process by which the structures are produced.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540080435
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    Announcement (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 562-562 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080437
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    Masthead (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987) 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080501
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    Towards a quantum chemical software package utilizing transferable fragments as molecular building blocks (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 555-561 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Computer programs have been developed or are under development for the IBM personal computer that enable their users to get information on atomic charges, electrostatic potentials, conformational and other properties of molecular systems containing H, C, N, O, F, Si, P, S, or Cl atoms. The zero-order wavefunction is constructed of strictly localized molecular orbitals with fixed atomic orbital coefficients. The wave function can be refined by optimizing these coefficients, i.e., considering inductive effects via a coupled set of 2 × 2 secular equations within the CNDO/2 approximation. Delocalization and exchange effects are accounted for by expanding the wavefunction on a basis of the aforementioned strictly localized orbitals, instead of conventional atomic orbitals, and solving the corresponding SCF equations. Our method has been applied to the study of large systems. We calculated the electrostatic field of the complex of β-trypsin and basic pancreatic trypsin inhibitor and it has been found that strong field regions more or less coincide with hydration sites. A further potential application of protein electrostatic fields is in NMR spectroscopy. We found a linear correlation between CαH or backbone NH proton chemical shifts and the protein field at the site of the corresponding proton. At last, we propose a simple method to mimic the bulk around atomic clusters modeling crystalline and amorphous silicon. Based on this method we found a linear correlation between atomic net charges and bond angle distortions in silicon clusters with 35 atoms.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540080436
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    Strain energy minimization study of the mechanism of, and the barrier to, conformational interconversion in five-membered diamine chelate rings (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 651-657 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The method of Lagrangian multipliers is used to constrain torsion angles during molecular mechanics refinement for the purpose of plotting strain energy against a reaction coordinate. A complete two-dimensional analysis of the conformational interconversion from δ- to λ-[Co(ethane-1,2-diamine) (NH3)4]3+ reveals a mechanism in which the transition state geometry has an envelope conformation and an inversion barrier of 15.7 kJ mol-1. Substitution at the carbon atoms, variation of the metal-nitrogen distance, and replacement of the amine ligands with bidentate amines only slightly alters the inversion barrier. Substitution at the nitrogen atoms of the bidentate ligand increases the inversion barrier significantly to 24.6 kJ mol-1 for (N,N,N′,N′-tetramethylethane-1,2-diamine) [(NH3)4]3+.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080510
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    Two approaches to the calculation of molecular resonance states: Solution of scattering equations and matrix diagonalizationPresented at the Symposium on Computation and Mathematical Chemistry, Saskatoon, Canada, June 1-4, 1986. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 683-699 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We have analyzed two approaches to reproduce the resonance expansion of the scattering matrix appropriate for the calculation of molecular resonance states. The first is based on the resonance theory of Siegert-Humblet-Rosenfeld (SHR) and the second on the Fano-Feshbach formalism. The direct method of calculating the resonance expansion characteristics, devised on the basis of the SHR theory, makes it possible to obtain the energies and partial widths (detailed decay rate constants) of resonances. The Fano-Feshbach formalism, on the other hand, elucidates the resonance state as a concept and facilitates the interpretation of calculation results. The use of computational methods is illustrated by the study of the decay of a model triatomic system and of gas-phase nucleophilic substitution reactions. Used in the latter case is the division of all degrees of freedom of the reacting system into the adiabatic and dynamic ones along with an algorithm of inclusion of the restricted dynamical treatment in the calculation of reaction rate constants.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080514
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    The inverse problem of isomer enumerationPresented at the Symposium on Computation and Mathematical Chemistry, Saskatoon, Canada, June 1-4, 1986. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 700-717 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The present article addresses the problem of identifying the structure of a parent compound through its chemical fingerprints such as the various numbers of isomeric substitution patterns, along the lines of Kekulé when he arrived at his benzene formula. In a pioneering paper (1929), Lunn and Senior laid out the conceptual framework for the permutation group description of substitution isomerism. It remained, however, for Pólya's celebrated contribution (1937) to initiate the actual mathematical realization of their vision. Pólya supplied the tools for solving the isomer enumeration problem: given a (symmetrical) parent compound, enumerate its spectrum of substitution patterns. The converse problem, though ranked the more interesting one by Lunn & Senior, hardly received any mathematical attention. The present article offers a complete and effective solution.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540080515
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    Molecular graphs as topological objects in spacePresented at the Symposium on Computation and Mathematical Chemistry, Saskatoon, Canada, June 1-4, 1986. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 718-726 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Stereochemistry deals primarily with distinctions based on rigid geometry, e.g., bond angles and lengths. But some chemical species have molecular graphs (such as knots, catenanes, and nonplanar graphs K5 and K3.3) that reside in space in a topologically nontrivial way. For such molecules there is hope of using topological methods to gain chemical information. Viewing a molecular graph as a topological object in space makes it unrealistically flexible; but if one proves that a certain graph is “topologically chiral” or that two graphs are “topological diastereomers,” then one has ruled out interconversion under any physical conditions for which the molecular graph still makes sense. In this paper, we consider several kinds of topological questions one might ask about graphs in space, methology and results available, and specific topological properties of various molecules.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080516
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    Hartree Fock instabilities of sulfur-nitrogen ring systems: S2N2Presented at the Symposium on Computation and Mathematical Chemistry, Saskatoon, Canada, June 1-4, 1986 (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 727-735 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The Hartree-Fock instablities of S2N2 are reported and compared with those of S3N3- and S4N42+. These unsaturated sulfur nitrogen planar rings are π electron rich and although the symmetry adapted HF solutions are singlet stable at the experimental bond lengths they become unstable with only a very modest increase in bond length. The broken symmetry solutions for S2N3, S3N3-, and S4N42+ are of planar C2v type with one of the nitrogens stripped of its π electrons, producing a π hole.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080517
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    Masthead (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987) 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080601
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    Ab-initioMRD-CI calculations on a C—NO2 decomposition pathway of nitrobenzenePresented at the Symposium on Computation and Mathematical Chemistry, Saskatoon, Canada, June 1-4, 1986. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 736-743 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: To study molecular decomposition pathways it is necessary to use ab initio multireference determinant-configuration interaction or MCSCF (multiconfiguration SCF) calculations. The MRD-CI (multireference double excitation-configuration interaction technique of Buenker and Peyerimhoff) calculations on the decomposition pathway of nitrobenzene were carried out using all of the occupied molecular orbitals in the region of the bond being dissociated, plus all of the virtual orbitals. An effective CI Hamiltonian was used into which were folded the effects of all of the occupied molecular orbitals from which excitations were not allowed. So far we have investigated the lowest 1A1, 3A1, 1A2, 3A2, 1B1, 3B1, 1B2, 3B2 states and are investigating the higher states. Our results show a wealth of structure in the potential energy surfaces for the various electronic states of nitrobenzene as a function of distance. A number of the states are predissociative and change dominant configuration one or more times along these potential energy surfaces.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080518
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  • 68
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    Hamiltonian dynamics of chemical reactions. Consecutive first-order reactions and reactions possessing one autocatalytic intermediatePresented at the Symposium on Computation and Mathematical Chemistry, Saskatoon, Canada, June 1-4, 1986. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 744-751 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A recently proposed Hamiltonian approach to phenomenological chemical kinetics [T. Georgian and G.L. Findley, Int. J. Quantum Chem., Quantum Biol. Symp. 10, 331 (1983); T. Georgian, J.M. Halpin, and G.L. Findley, Int. J. Quantum Chem., Quantum Biol. Symp. 11, 347 (1984)] is applied to all consecutive first-order, single-step reactions, and to all reactions possessing one autocatalytic intermediate. The reaction Hamiltonians presented are shown to be consistent with the phenomenological rate equations and the relationship between reaction form and the form of the reaction potential is discussed. In particular, we show: (1) that the interaction between consecutive reactions manifests itself as a coupling term in the reaction potential, a term which may be eliminated via transition to “normal reaction coordinates” for the chemical system; and (2) that coupled sets of autocatalytic reactions give rise to coupling terms in the reaction Hamiltonian which are characteristic of the reaction mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080519
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  • 69
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    Column design. 3. Theoretical studies of a chiral stationary phase used in column chromatography (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 753-760 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Conformational features of a chiral stationary phase used in column chromatography are discussed. The syn forms invoked in chiral recognition models are consistent with MNDO and MM2 calculations. It is speculated that the inherent flexibility of the syn form makes these phases effective templates for analyte binding.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540080602
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  • 70
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    Ab initio study of the He(1S)-Li2(X̃, 1∑g+) interaction by the SCF and MP2 methods (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 761-771 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Ab initio electronic structure calculations have been carried out for the He(1S)-Li2 (X̃, 1∑g+) interaction both by the single-configuration SCF and correlated second-order MP2 methods using an extended basis set. From these calculations, an estimate of the isotropic (V0) and first two anisotropic (V2 and V4) terms of the He-Li2 potential surface has been obtained. An assessment of the leading induced-dipole-induced-dipole dispersion energy is presented from the MP2 energies. Where possible, a comparison is made with previous unpublished ab initio calculations by Staemmler and Stahl using the CEPA method.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080603
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  • 71
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    CNDO Force constants for glucose (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 772-777 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Force constants for both anomers of glucose are evaluated using CNDO/Force method.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540080604
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  • 72
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    Electrostatic interaction of a solute with a continuum. Improved description of the cavity and of the surface cavity bound charge distribution. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 778-787 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Algorithms for a finer description of cavities in continuous media and for a more efficient selection of sampling points on the cavity surface are described. Applications to the evaluation of solute surface and volume and to the calculation of the solute-solvent electrostatic interaction energy, as well as of the cavitation energy are shown as examples.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540080605
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  • 73
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    A study of basis set effects on structures and electronic structures of phosphine oxide and fluorophosphine oxide (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 788-793 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A variety of basis sets have been used for geometric and electronic structure studies. Electronic effects were measured using integrated spatial electron populations (ISEP). The two largest basis sets used, 6-31G* and DZ+P, give significantly different results. Use of two d-orbital sets (6-31G*[dd]) or decontraction of the 2sp shell on phosphorus has little further effect. d-Orbitals on oxygen are required for consistent electronic structure results, and d-orbitals on fluorine have a small but significant effect. Use of diffuse functions, required for anions, is not recommended with small basis sets on neutral molecules. Large negative charges (≈-1.5) on oxygen are given by all of the larger basis sets by the ISEP procedure and indicate that the PO bond in these compounds is largely semi-polar. The best simple symbolic representation of phosphine oxide is H3P+—0-, rather than H3P=0.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080606
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  • 74
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    Basis set and correlation effects on computed positive ion hydrogen bond energies of the complexes AHn · AHn + 1+1: AHn = NH3, OH2, and FH (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 810-815 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Basis set expansion and correlation effects on computed hydrogen bond energies of the positive ion complexes AHn · AHn + 1+1, for AHn = NH3, OH2 and FH, have been evaluated. The addition of diffuse functions on nonhydrogen atoms is the single most important enhancement of split-valence plus polarization basis sets for computing hydrogen bond energies. Basis set enhancement effects appear to be additive in these systems. The correlation energy contribution to the stabilization energies of these complexes is significant, with the second order term being the largest term and having a stabilizing effect. The third order term is smaller and of opposite sign, while the fourth order term is smaller yet and stabilizing. As a result, computed MP4 stabilization energies are bracketed by the MP2 and MP3 energies. The overall effect of basis set enhancement is to decrease hydrogen bond energies, whereas the addition of electron correlation increases stabilization energies.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/jcc.540080609
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  • 75
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    A powerful truncated Newton method for potential energy minimizationThis work would not have been possible without the expert contibutions of Charles Peskin and Suse Broyde. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1025-1039 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: With advances in computer architecture and software, Newton methods are becoming not only feasible for large-scale nonlinear optimization problems, but also reliable, fast and efficient. Truncated Newton methods, in particular, are emerging as a versatile subclass. In this article we present a truncated Newton algorithm specifically developed for potential energy minimization. The method is globally convergent with local quadratic convergence. Its key ingredients are: (1) approximation of the Newton direction far away from local minima, (2) solution of the Newton equation iteratively by the linear Conjugate Gradient method, and (3) preconditioning of the Newton equation by the analytic second-derivative components of the “local” chemical interactions: bond length, bond angle and torsional potentials. Relaxation of the required accuracy of the Newton search direction diverts the minimization search away from regions where the function is nonconvex and towards physically interesting regions. The preconditioning strategy significantly accelerates the iterative solution for the Newton search direction, and therefore reduces the computation time for each iteration. With algorithmic variations, the truncated Newton method can be formulated so that storage and computational requirements are comparable to those of the nonlinear Conjugate Gradient method. As the convergence rate of nonlinear Conjugate Gradient methods is linear and performance less predictable, the application of the truncated Newton code to potential energy functions is promising.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/jcc.540080711
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  • 76
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    An efficient newton-like method for molecular mechanics energy minimization of large molecules (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1016-1024 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Techniques from numerical analysis and crystallographic refinement have been combined to produce a variant of the Truncated Newton nonlinear optimization procedure. The new algorithm shows particular promise for potential energy minimization of large molecular systems. Usual implementations of Newton's method require storage space proportional to the number of atoms squared (i.e., O(N2)) and computer time of O(N3). Our suggested implementation of the Truncated Newton technique requires storage of less than O(N1.5) and CPU time of less than O(N2) for structures containing several hundred to a few thousand atoms. The algorithm exhibits quadratic convergence near the minimum and is also very tolerant of poor initial structures. A comparison with existing optimization procedures is detailed for cyclohexane, arachidonic acid, and the small protein crambin. In particular, a structure for crambin (662 atoms) has been refined to an RMS gradient of 3.6 × 10-6 kcal/mol/Å per atom on the MM2 potential energy surface. Several suggestions are made which may lead to further improvement of the new method.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080710
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  • 77
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    On the out-of-plane deformation of aromatic rings, and its representation by molecular mechanics (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1051-1056 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: It has been found that the previous MM2 (or MMP2) description of out-of-plane deformation of aromatic rings sometimes yields distortions which are much too large. As a result, rotational barriers involving distortions of such rings may be calculated to have values which are too low. Examples are collected and discussed. An alternative formulation, which appears to significantly reduce the calculational error, is presented.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540080713
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    Scientific and engineering applications with personal computer, r. annino and r.d. driver. wiley, new york, 1986, $45.00, 577 pp. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1066-1067 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080715
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  • 79
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    Molecular orbital calculations on solvents and other small molecules: Correlation between electronic and molecular properties ν, αMOL, π*, and β. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1084-1089 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Molecular orbital calculation by the MINDO/3 method are reported for 50 compounds used as solvents in chemical reactions. Relationships between various parameters of electronic structure and molecular properties such as dipole moment, polarizability and Taft solvent parameters are presented. Comparison between experimental values of π* and calculated values is given.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080803
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    Systematic drug receptor mapping: A new approach to the analysis of conformational energy calculations of flexible molecules with application to dopaminergic and adrenergic agonists (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1075-1083 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The computer program PRODIS is used to find low energy conformations of flexible molecules by searching the potential energy surface(s) of one or more torsion angles via rigid rotation. The n-dimensional grid of energy versus torsion angles is then converted to a Boltzman probability distribution, with the probability being represented not as a function of torsion angle, but rather a distance between two atoms. These atoms are chosen by comparison with a known, active analogue in which certain atoms have previously been determined as requirements for drug activity. PRODIS produces a list of low energy conformations, their corresponding interatomic distances and the Boltzman probability for each distance ±0.125, as well as the total probability for each conformation. The user also specifies a target interatomic distance and range (usually derived from a more rigid analogue) for which PRODIS lists all conformations and their Boltzman probability that meet this distance.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080802
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    On the use of constraints in molecular mechanics. II. The Lagrange multiplier method and non-full-matrix Newton-Raphson minimization (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1099-1103 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: It is shown how the Lagrange Multiplier method for constrained minimization can be implemented in a molecular mechanics program using the common approximations to the full-matrix Newton-Raphson minimization. The method reduces the number of cycles to achieve convergence, and also stabilizes the refinement process. Increases in computer memory requirements are small. As an application, the conformational surface of cycloheptane is calculated.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540080805
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  • 82
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    Molecular mechanics study of myelin basic protein (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1104-1108 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Myelin basic protein (MBP) is the major extrinsic protein of the myelin sheath in the central nervous system. We have examined the predicted structure of segments of MBP using the molecular mechanics program ECEPP83 developed by Scheraga and coworkers as modified by Chuman, Momany, and Schafer. We have focused upon segments containing the Pro-Pro-Pro sequence (residues 100-102), which have been predicted from standard algorithms to exist in a hairpin loop connecting anti-parallel beta-strands. Both the shorter (98-105, 99-105, and 100-105) and longer segments (87-109, 87-118, and 87-120) have been examined. These results indicate potential for a chain reversal in this region. The shorter segments have been studied by others using NMR techniques and the results are compared.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540080806
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    An evaluation of the performance of diffuse function-augmented basis sets for second row elements, Na-ClPart IV of a series on Efficient Diffuse Function-Augmented Basis Sets for Anion Calculation. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1109-1116 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The energetic effects of the addition of diffuse functions to molecules with second-row elements are much less dramatic than those for their first-row counterparts. Although diffuse functions on second-row elements have little effect on the geometries and vibrational frequencies of neutral molecules, significant changes are found for anions. While the largest basis set, 6-31 + G*, generally performs best, the results at 3-21 + G* are comparable, and this basis can be recommended for practical applications.
    Additional Material: 10 Tab.
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    URL: http://dx.doi.org/10.1002/jcc.540080807
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    Semi-empirical calculations of molecular trajectories: Method and applications to some simple molecular systems (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1117-1123 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The MNDO Hamiltonian as incorporated within MOPAC has been utilized to predict dynamics for some simple reactions. In one option, the intrinsic reaction coordinate has been followed along the path of steepest descent from the transition state backward to reactants and forward to products. In a second option, dynamics of isolated molecular systems have been calculated. In each case, the potential surface (as predicted by the MNDO Hamiltonian) is calculated in situ as the atomic trajectories are calculated from Newton's Laws of Motion. Several specific examples are given and discussed.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540080808
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    Cooperative effects in extended hydrogen bonded systems involving O—H groups. Ab initio studies of the cyclic S4 water tetramer (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1090-1098 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The additional energy stabilization due to cooperative effects was calculated in extended hydrogen bonded systems O—H⃛O—H⃛O—H with unidirectional (homodromic) orientation of the O—H groups. Ab initio restricted Hartree Fock, MP2 and MP3 calculations with geometry optimization and BSSE correction have been performed using the GAUSSIAN 83 program package for the ground states of the linear water dimer with Cs symmetry and the cyclic water tetramer with S4 symmetry. The latter represents the smallest possible, experimentally observed cooperative structure. A new definition for a cooperativity parameter is proposed. The definition is based on the two-body, non-neighbour interaction energy, plus three- and four-body contributions, including one-body deformation terms in relation to the total interaction energy of the water tetramer. The advantage of this definition is its independence of the reference system, which is necessary in complicated molecular systems with an undefined number of hydrogen bonds, such as disordered or flip-flop systems. According to this definition the energy gain based on cooperativity in the S4 water tetramer is 29% with the MP3/6-31G** approximation, (30% with HF/4-31G* and 46% with HF/3-21G). The largest contribution of 18% is due to the three-body term on the MP3/6-31G** level, followed by the two-body, non-neighbour term with 11%. The four-body term and the deformation term are in the order of 1% and cancel each other because they have opposite sign.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540080804
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  • 86
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    Nonbonded interactions. 1. Anisotropic hydrogen-hydrogen interactions (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1124-1130 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The hydrogen-hydrogen nonbonded potential which may be derived from the calculated interactions between hydrogen molecules has been obtained. The best three-parameter Buckingham function gave an RMS error of 0.18 kcal/mol in fitting Price and Stone's ab initio data for 130 pairs of hydrogen molecules, which may be compared with an RMS error of 0.74 kcal/mol using the parameters in the MM2 force field. Burton's basis set is also considered. A better fit to these data requires that the angular relationship between the bonds be included. The data for hydrogen as well as experimental data for chlorine show that these atoms appear “larger” normal to the bond axis than along the axis, and this is probably also the case for other atoms. When simple angular terms are added it is possible to fit the Price and Stone data set with an RMS error of less than 0.06 kcal/mol. The preferred function was: V = [a0 + a1(sin θ1 + sin θ2)4 + a2r]e-3r - [c0 + c1(1 + sinθ1sinθ2)]/r5. Deficiencies in the current ab initio data are discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080809
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    An analysis of the structural and energetic properties of deoxyribose by potential energy methods (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1199-1224 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We discuss the three fundamental issues of a computational approach in structure prediction by potential energy minimization, and analyze them for the nucleic acid component deoxyribose. Predicting the conformation of deoxyribose is important not only because of the molecule's central conformational role in the nucleotide backbone, but also because energetic and geometric discrepancies from experimental data have exposed some underlying uncertainties in potential energy calculations. The three fundamental issues examined here are: (i) choice of coordinate system to represent the molecular conformation; (ii) construction of the potential energy function; and (iii) choice of the minimization technique. For our study, we use the following combination. First, the molecular conformation is represented in cartesian coordinate space with the full set of degrees of freedom. This provides an opportunity for comparison with the pseudorotation approximation. Second, the potential energy function is constructed so that all the interactions other than the nonbonded terms are represented by polynomials of the coordinate variables. Third, two powerful Newton methods that are globally and quadratically convergent are implemented: Gill and Murray's Modified Newton method and a Truncated Newton method, specifically developed for potential energy minimization. These strategies have produced the two experimentally-observed structures of deoxyribose with geometric data (bond angles and dihedral angles) in very good agreement with experiment. More generally, the application of these modeling and minimization techniques to potential energy investigations is promising. The use of cartesian variables and polynomial representation of bond length, bond angle and torsional potentials promotes efficient second-derivative computation and, hence, application of Newton methods. The truncated Newton, in particular, is ideally suited for potential energy minimization not only because the storage and computational requirements of Newton methods are made manageable, but also because it contains an important algorithmic adaptive feature: the minimization search is diverted from regions where the function is nonconvex and is directed quickly toward physically interesting regions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080817
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  • 88
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    Masthead (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987) 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080101
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  • 89
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    Recursion formulae for calculation of overlap integrals (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 1-5 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Multi-ζ Slater-type orbitals are frequently used in molecular orbital calculations. Master formulae and numerical tables are available in literature for overlap integrals between s, p, and d atomic orbitals up to principal quantum number (n) = 3 and for some other selected quantum numbers. However, no master formula or numerical table is available for quantum numbers n = 5 and above and involving ƒ orbitals. In this article recursion formulae have been presented for the calculation of the overlap integral between any two s, p, d, and ƒ atomic orbitals formed by a linear combination of Slater-type orbitals. These formulae, when expanded, would give rise to all the master formulae reported in the literature as well as formulae hitherto unreported.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080102
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  • 90
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    Molecular modeling of polymers: I. Correct and efficient enumeration of intrachain conformational energetics (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 28-38 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Polymer conformational analyses can require being able to model the intramolecular energetics of a very long (infinite) chain employing calculations carried out on a relatively short chain sequence. A method to meet this need, based upon symmetry considerations and molecular mechanics energetics, has been developed. Given N equivalent degrees of freedom in a linear polymer chain, N unique molecular groups are determined within the chain. A molecular unit is defined as a group of atoms containing backbone rotational degrees of conformational freedom on each of its ends. The interaction of these N molecular groups, each with a finite number of nearest neighbors, properly describe the intramolecular energetics of a long (infinite) polymer chain. Thus, conformational energetics arising from arbitrarily distant neighbor interactions can be included in the estimation of statistical and thermodynamic properties of a linear polymeric system. This approach is called the polymer reduced interaction matrix method (PRIMM) and the results of applying it to isotactic polystyrene (I-PS) are presented by way of example.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080104
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  • 91
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    Recent advances in multireference second order perturbation CI: The CIPSI method revisited (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 39-47 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The evolution of the CIPSI method, with the latest modifications recently implemented in our laboratory, is described. A new version, based on a diagrammatic technique, is presented. Test calculations which have been run on water, ethylene, and transacrolein, show that the new method is a powerful tool for the study of medium-size molecular systems.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080105
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  • 92
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    The role of d functions in ab initio calculations. II. The deformation densities of SO2, NO2, and their ions (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 6-27 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Comparison of the optimized geometries and SCF energies for the series XO2+, XO2, XO2-, XO2-, with X = S,N shows that d(S) functions cause larger bond shortening and energy drop than d functions centered on first-row atoms. This is further emphasized on comparing the separate effects of d(central atom) and d(O) functions for SO2 and NO2-, which are similar only for the first-row molecule. The d(S) functions are also essential for proper prediction of the OSO angles. The deformation densities calculated for each series and the corresponding X-O shared populations, change as expected on adding electrons first into σ* then into π* molecular orbitals. In the regions around nuclei the deformation densities express the behavior of the atomic s and p valence orbitals or of their product inside their radial nodes. Introduction of d functions causes substantial polarization effects. For X = N these are mostly local except in the bonding regions where d(N) and d(O) functions are somewhat interchangeable. However, d(S) functions induce also unique changes in the deformation density near O. They cause π and π′ charge migration from O to S and a σ flow in the opposite direction. These effects are largest for the hypervalent species. The unique populations of the d(S) functions are much larger than those of d(N) and d(O) functions. The contribution of d(S) functions to bonding is related to the larger amplitude at small radii of the atomic 3d(S) orbital as compared with that of 3d(N). The difference in amplitudes is related to penetration effects. Diffuse p functions affect geometries and SCF energies of doubly, but not singly negative ions. However, they mostly describe the diffuse nonbonding clouds and do not affect bonding patterns.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540080103
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  • 93
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    On the importance of size-consistency corrections in semiempirical MNDOC calculations (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 48-50 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Energies obtained by configuration interaction calculations including all double excitations with regard to the Hartree-Fock reference determinant can empirically be corrected to size consistency using either the Langhoff-Davidson (LD) formula or a formula suggested by Pople, Seeger, and Krishnan (PSK). Semiempirical MNDOC calculations suggest that for molecular systems with a large number of electrons and important correlation effects the PSK correction is superior to the LD correction.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080106
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  • 94
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    Ab initio studies on van der Waals molecules. A comparative study with several basis sets of the C2v HeLi2 systemThis work was financially supported by the CAICYT No. 0637/81. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 51-56 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The potential energy surface of the van der Waals system HeLi2 is computed for the case in which the system has C2v symmetry and at the Li-Li distance (5.005 bohrs). A comparative study of the results for the two methods used, ab initio Hartree-Fock and second-order Møller-Plesset, and several basis sets, ranging from minimal to near Hartree-Fock quality, is also done. The results show the importance of correcting the basis set superposition error, and the need, in order to obtain a good description of the potential, of basis sets with polarization functions on all the atoms, when the Møller-Plesset method is used. At the Hartree-Fock level, the MINI-1 basis gives results almost of the same quality as the near Hartree-Fock basis.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080107
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  • 95
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    Theoretical study of water-pyridine complexes using intermolecular potentials (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 67-80 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Intermolecular potential functions have been used to determine the equilibrium structures of the water-pyridine complexes. The dimer and symmetrical 2:1 water pyridine systems have been studied. Three water models, ST2, TIPS2, and EMPWI have been combined with two different Lennard Jones nonbonded parameters and various charge distributions for the pyridine molecule to describe the systems. For the dimer, results show two distinguishable classes of preferential hydration sites, which are specific sites corresponding to hydrogen-bonded dimer and nonspecific sites located near the hydrophobic regions. Calculations performed on hydrogen-bonded symmetrical complexes show that the planar complex is generally less stable than the complex with water molecules perpendicular to the pyridine plane. For these complexes, the major factor that influences the hydrogen-bonded configurations is the choice of the water model. The importance of atomic charge distributions for the solute over the choice of potential parameters is pointed out. Finally, the effective lone pair representation on the aromatic nitrogen atom is shown to improve the hydrogen bond geometry and the stability of the complexes.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080109
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  • 96
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    Polarization counterpoise corrections to correlated hydrogen bond interaction energies (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 81-83 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Basis set superposition error in hydrogen-bonded systems can exaggerate attraction calculated from self-consistent field energies as well as from electron correlation energies. One cause of this error is the basis set deficiency in describing the charge polarization of one constituent molecule when its bonding partner approaches. That constituent molecule's description is improved partly because of the proximity of the partner's basis functions, independent of real attraction. That polarization-related error is shown to occur primarily at the SCF level and not at correlated levels.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080110
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  • 97
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    Masthead (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987) 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080201
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  • 98
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    Ab initio calculations on the effect of polarization functions on disiloxane (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 84-93 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The effect of polarization functions for ab initio molecular orbital calculations at the 3-21G* level has been studied for disiloxane. Calculated molecular geometry, dipole moment, and the linearization barrier variation were analyzed for different uncontracted polarization functions. It was concluded that variation of the polarization function on oxygen has only a minor influence on the molecular properties of disiloxane, but its presence is required to obtain a bent geometry for the disiloxane bond. The calculated molecular properties of disiloxane are greatly influenced when the polarization function on silicon is varied. Two different values (0.3 and 0.9) for the exponent of the silicon polarization function provide results comparable to the experimental values for disiloxane. The only significant differences between the results obtained from ab initio calculations using the two polarization functions are in net atomic charges. The uncontracted polarization function of silicon with a value of 0.3 for its exponent is transferable to other organosilicon compounds. Calculated molecular geometries of flexible or rigid structures are in very good agreement with the experimental values.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080111
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  • 99
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    Optimized method for the evaluation of the convolutionally distorted decay curves (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 95-106 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A nonlinear least squares procedure based on the Meiron method is described for the evaluation of the convolutionally distorted decay curves consisting of exponentials. Most of the special procedures are well known and the selected ones proved to be the most effective. Some new procedures are introduced to facilitate the evaluation work and literature data are analyzed as an example.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080202
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  • 100
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    Combination of MOMM and VEH methods to calculate electronic properties of polymers (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 107-116 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A Molecular-Orbital-Based Molecular Mechanics method (MOMM) has been employed to calculate the structures of cyclopentadiene, pyrrole, furan, thiophene, dibenzocyclopentadiene (fluorene), dibenzopyrrole, dibenzofuran, and dibenzothiophene. The dimer structures of the above compounds have also been calculated using the same method to derive the unit cells of polycyclopentadiene, polypyrrole, polyfuran, polythiophene, polydibenzocyclopentadiene, polydibenzopyrrole, polydibenzofuran, and polydibenzothiophene. The band structures, densities of states, ionization potentials, band gaps, reduction potentials, and oxidation potentials of these polymers then have been calculated by using the Valence Effective Hamiltonian method (VEH). The structural effects on electronic properties are discussed.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540080203
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