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  • 1
    Electronic Resource
    Electronic Resource
    Study of diethyl 3,12-diaza-4,11-dioxotetradecanedioate as a model compound of poly(ester amide)s derived from glycine (1998)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 199 (1998), S. 1167-1173 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The conformation of the molecule of diethyl 3,12-diaza-4,11-dioxotetradecanedioate (EtGSGEt) has been investigated in the crystalline state by X-ray analysis. EtGSGEt crystallizes in the monoclinic system, space group P1121/n with a = 4.8174(7) Å, b = 4.9008(5) Å, c = 43.616(5) Å and γ = 112.854(10)°. 965 independent reflections were used in the refinement to the final agreement factor of R = 8.36%. The glycine residues of EtGSGEt are related by an inversion center and adopt a conformation, which slightly deviates from that characteristic of the polyglycine II structure. An all-trans conformation was deduced for the suberamide unit. The packing characteristics of the diamide are similar to that found in the α form of nylons.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Preparation and crystalline structure of random copolymers of glycine and β-alanine (1989)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 190 (1989), S. 1379-1387 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Copolymers of glycine and β-alanine within a range of amount-of-substance compositions from 3:1 to 1:9 were prepared by polycondensation of mixtures of the respective pentachlorophenyl ester hydrobromides. Number-average molecular weights between 2 500 and 9 000 were obtained, the lower values corresponding to those copolymers with a higher content in glycine. Sequence distributions were evaluated by means of 50,3 MHz 13C NMR spectroscopy and the crystalline structure was examined by wide-angle X-ray diffraction. Random copolymers having similar contents in glycine and β-alanine were found to crystallize in a bidimensional hexagonal lattice (a = 4,79 Å) with chains packed in a similar manner as they do in the crystalline structure of polyglycine II. On the contrary, a heterogeneous product consisting of homopolymer and random copolymer fractions results from mixtures which are enriched in one of the two amino acids. The random copolymer poly(glycine-ran-β-alanine) adopts a packing scheme similar to that found for the helical form of the alternating copolymer nylon 2/3. Chains are hexagonally arranged and interlinked by a three-dimensional network of hydrogen bonds as described for the well known model of polyglycine II, although in the present case no order along the chain axis should be expected.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1989.021900618
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis and structural data of nylon 1,4 (1987)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 1445-1448 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1987.080250520
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  • 4
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of glycine copolymers of nylons 6 and 12 (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 727-741 
    Details
    ISSN: 0887-624X
    Keywords: copolyamides ; nylons ; glycine ; x-ray diffraction ; NMR spectroscopy ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Copolymers of glycine and 6-aminohexanoic or 12-aminododecanoic acid within a range of molar compositions from 80/20 to 5/95 were prepared by solution polycondensation of the adequate proportion of the respective pentachlorophenyl ester hydrobromides. Despite their random composition, the copolymers obtained were found to be highly crystalline. Intrinsic viscosities of 2/6 and 2/12 copolyamides were similar and rather low (Mn, ca. 3000-5000). Thermal post-polycondensation allowed to increase the molecular weight of 2/12 copolyamides, so that fibers could be prepared. The composition and sequence distributions were evaluated by means of 1H- and 13C-NMR spectroscopies. Copolyamides were also characterized in terms of thermal properties. Melting and glass transition temperatures are reported. Crystallinity was evaluated from heats of fusion. Crystalline structure was examined by infrared spectroscopy and wide-angle x-ray diffraction. The presence of structures related to the polyglycine I and to α/γ-nylons was confirmed depending on the molar composition. Highly oriented fibers with good tensile properties were obtained from the nylon 2/12 (10 : 90) copolymer. © 1995 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080330414
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  • 5
    Electronic Resource
    Electronic Resource
    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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  • 6
    Electronic Resource
    Electronic Resource
    An experimental Ramachandran plot for retropeptide derivatives: Conformational features of derivatives of GEM-diamino and malonyl amino acids (1998)
    New York : Wiley-Blackwell
    Biopolymers 45 (1998), S. 149-155 
    Details
    ISSN: 0006-3525
    Keywords: malonamide ; diaminomethane ; retropeptide ; retro-glycine ; peptide conformation ; Ramachandran plot ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Malonic and diaminomethane residues, equivalent to the two possible retro modifications of a glycine unit, with an inverted peptide group, present particular conformations that differ from those found in glycine and, in general, in α-amino acids. In both cases the ϕi and ψi torsional angles have restricted values as deduced from inspection of the Cambridge Structural Data Bank and from compounds studied by us. Thus, both ψi angles tend to be equal to 115° (or -115°) in the malonyl residues, whereas the ϕi angles tend to be equal to 88° (or -88°) in the diaminomethane residues. These results are in agreement with previous experimental data on polymers, but in the case of malonyl residues they differ from theoretical calculations on isolated molecules. The experimental data for both residues can be represented in a way similar to the usual Ramachandran plot, which will be useful in analyzing the incorporation of these residues into proteins. When side chains are present in either type of residue, they are similar to conventional α-amino acids, although the orientation of the peptide groups is different. In such cases they acquire conformations similar to those found in peptide residues in the α-helix and β-sheet conformations, although other conformations are also possible. © 1998 John Wiley & Sons, Inc. Biopoly 45: 149-155, 1998
    Additional Material: 3 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Crystal structure of a helical oligopeptide model of polyglycine II and of other polyamides: Acetyl-(glycyl-β-alanyl)2-NH propyl (1992)
    New York : Wiley-Blackwell
    Biopolymers 32 (1992), S. 643-648 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We synthesized and solved the crystalline structure of the oligopeptide acetyl- (glycyl-β-alanyl)2-NH propyl. The crystal is formed by layers of helical molecules with the same chirality; however, right-handed layers alternate with left-handed ones. Inside every layer, the packing of helices is pseudohexagonal with hydrogen bonds between neighbor molecules. The structure found affords direct support for the model proposed by Crick and Rich for polyglycine II and also provides an interpretation for the structure of a newly found family of polyamides that do not form sheets as observed in most nylon structures.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360320607
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  • 8
    Electronic Resource
    Electronic Resource
    Incorporation of diacids into the polyglycine II structure: Model studies (1995)
    New York : Wiley-Blackwell
    Biopolymers 36 (1995), S. 711-722 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aliphatic diacids Eare often incorporated into polypeptide structures in order to obtain model compounds for hormones, protein turns, etc. They are also fundamental components of many commercial polyamides. On the other hand glycine, the simplest amino acid, shows unique conformational features. In order to better understand the structure of such compounds, we have synthetized and determined the molecular structure of three models represented by the general formula CH3-CH2CH2-NH-CO-CH2NH-CO-(CH2)n-2-CO-NH-CH2CO-NH-CH2CH2CH3, with n = 3, 4, or 6. Conformational differences have been found in the dicarboxylic moiety, whereas glycine always has the polyglycine II conformation. The -CO-(CH2)n-2-CO- segment adopts a folded conjformation: SS, TGT, and SḠTGS̄ for n = 3, 4, and 6, respectively. Molecular packing is always pseiidohexagonal and a network of hydrogen bonds oriented in three directions at 120° is formed. The results are of interest in order to provide information about polyamides in which gljrine residues are incorporated. Our results confirm the tendency of glycine residues to adopt the polyglycine II conformation in its copolymers with aliphatic compounds. © 1995 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360360605
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  • 9
    Electronic Resource
    Electronic Resource
    Structural data and thermal studies on nylon-12,10 (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 2065-2073 
    Details
    ISSN: 0887-6266
    Keywords: polyamides ; nylons ; x-ray diffraction ; electron microscopy ; Sebacamide ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The structure and morphology of Nylon-12, 10 lamellar crystals has been investigated using transmission electron microscopy, selected area electron diffraction, and x-ray diffraction. Additional data have been obtained from uniaxially oriented fibers. The unit cell parameters of two crystalline structures have been determined. They are similar to those usually found in other polyamides (α and β form). Calorimetric (DSC) studies on nylon 12, 10 were also carried out. Melting curves indicate that changes in the internal structure occur when scanning speeds less than 80°C min-1 are used. ©1995 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1995.090331408
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  • 10
    Electronic Resource
    Electronic Resource
    Chain conformation in polyretropeptides. II. Quantum mechanical and empirical force field calculations on 2,5,9,11-Tetraoxo-3,6,8,12-tetraza-tridecane, a model compound for the terpolymer of glycine and its retropeptides (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 1327-1338 
    Details
    ISSN: 0887-6266
    Keywords: conformational analysis ; 2,5,9,11-tetraoxo-3,6,8,12-tetraza-tridecane ; poly-retropeptide ; polyglycine ; α-helix ; glycine ; malonyl ; dimethylendiamine ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A conformational study of the terpolymer of glycine and its retropeptides monomethylen-diamine (gGly) and malonyl (mGly) with sequence: (-Gly-gGly-mGly-), is presented. First, we investigated the conformational preferences of the model molecule 2,5,9,11-tetraoxo-3,6,8,12-tetraza-tridecane using quantum mechanical calculations. The results indicated that the compound has a strong tendency to fold, giving intramolecular hydrogen bonds. Interestingly, the C13 (intramolecular 13-membered ring hydrogen-bonded system) conformation, which is the pattern of an α-helix conformation, was characterized as a minimum. Force-field calculations in an infinite chain model showed that there are two preferred conformations to this regular polyretropeptide. These correspond to an α-helix and a 6-fold helix stabilized by intramolecular and intermolecular hydrogen bonds, respectively. © 1996 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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