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  • 1
    Electronic Resource
    Electronic Resource
    Intermolecular interactions of globular proteins in the crystal state (1979)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 16 (1979), S. 437-444 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The present work is devoted to investigation of thermal transitions in the crystals of seven proteins to compare the protein globule stability in crystal and solution. Calorimetry methods, electron and optical microscopy, as well as x-ray diffraction studies are used. It is found that protein crystals do not melt and that the destruction of the crystal lattice is a result of protein globule denaturation within the crystal. It is demonstrated that during the heating of pepsin and DF-trypsin crystals it is possible to observe phase transition of the first order. Equilibrium temperatures of protein denaturation in crystals and in solution coincide. The peculiarities of the crystal state are revealed in the increasing thermal transition cooperativity and the system relaxation period.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560160304
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  • 2
    Electronic Resource
    Electronic Resource
    Conformational analysis of polytripeptides (Gly-Pro-Ala)n, (Gly-Ala-Hyp)n, and (Gly-Ala-Ala)n in connection with the problem of collagen structure (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1499-1512 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformational analysis of triple helics of a type of collagen was performed with typical collagen tripeptide sequences based on Gly-Pro-Ala, Gly-Ala-Hyp, and Gly-Ala-Ala. During energy minimization, the possibility of continual deformation of the pyrrolidine cycle was taken into account in order to achieve better accuracy in the resulting structure. The (Gly-Pro-Ala)n structure is almost isomorphic to the (Gly-Pro-Hyp)n structure obtained in the previous work [Tumanyan, V. G. & Esipova, N.G. (1982) Biopolymers 21, 475-497]. For a collagen-type structure, the optimal conformation of (Gly-Ala-Hyp)n tends to have a decreased unit twist (t = 15°), although the energy advantage with respect to the conformation with t = 45° is not so significant. A similar situation is observed for (Gly-Ala-Ala)n. In this case, the energy decrease during unwinding to t = 15° from t = 45° is quite small. The conformations of (Gly-Ala-Hyp)n and (Gly-Ala-Ala)n with t = 15° exhibit a similarity with a triple complex of polyproline II helices - a noncoiled coil such as (Gly-Pro-Hyp)n and (Gly-Pro-Ala)n. A similar structure may be postulated for subcomponent cq1 of the first component of a human complement containing substantial Gly-X-Pro and Gly-X-Y tripeptide derivatives in the primary structure (X, Y = any amino acid). The results suggest that the observed helical symmetry of collagen (t = 36°) is a consequence of superposition of diffraction patterns (for sufficiently long segments) from various helices (t varies from ∼15° for Gly-X-Hyp and Gly-X-Y to ∼56° for Gly-Pro-Ala). For short alternating segments, some unification of different helical structures is possible.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230806
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  • 3
    Electronic Resource
    Electronic Resource
    Secondary structure of polypeptide hormones of the anterior lobe of the pituitary gland (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 5-22 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The specific secondary structure of a number of polypeptide hormones of the pituitary gland anterior lobe and their fragments were studied by CD in the peptide bond absorption region and by ir spectroscopy. The state of objects was examined in solvents of different polarity over a wide temperature range as well as in the solid state at different relative humidities. The predominant conformational state of a number of hormones in aqueous solution is shown to represent a left-handed helix of the poly(L-proline) II type. The reversible melting process of the left-handed helical conformation when heated in an aqueous solution appears to be noncooperative. Lowering the temperature stabilizes the left-handed structure. The transition mode of the left-handed form to the α-, and the β-forms on changing the solvent conditions was also studied. Contributions of peptide chromophores and of the aromatic amino acid side-group chromophores with CD bands in the region under study were determined by analysis of CD spectra. The data obtained allow correlating the conformation of separate fragments in the hormone chain with functional activity.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230103
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  • 4
    Electronic Resource
    Electronic Resource
    Infrared spectra and structure of synthetic polytripeptides (1978)
    New York : Wiley-Blackwell
    Biopolymers 17 (1978), S. 1197-1214 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A number of polytripeptides related to collagen, namely, (Gly-Pro-Pro)n, (Gly-Pro-Hyp)n, (Gly-Hyp-Hyp)n, (Gly-Pro-Ala)n, (Gly-Pro-Leu)n, (Gly-Pro-Gly)n,(Gly-Ala-Pro)n, (Gly-Ala-Hyp)n, (Ala-Pro-Pro)n, and (Ala-Hyp-Hyp)n were investigated by the method of ir spectroscopy and hydrogen-deuterium kinetics. Strength and order of interpeptide hydrogen bonds of the polytripeptides in a triple-helical conformation were found to depend on the amino acid composition and residue sequence in the triplets. Correlation of X-ray diffraction and spectroscopic data for (Gly-Pro-Hyp)n showed that the increase of the helix parameter in the process of dehydration is accompanied with the weakening of interpeptide hydrogen bonds. Influences of bound water on the length and order of interchain hydrogen bonding was also examined. It was shown that the incorporation of water molecules into the triple helix depends on the amino acid composition and residue sequence. Synthetic models and native collagens were compared.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1978.360170508
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  • 5
    Electronic Resource
    Electronic Resource
    Formation of the collagen-like triple-helical structure in oligopeptides during elongation of the molecular chain (1978)
    New York : Wiley-Blackwell
    Biopolymers 17 (1978), S. 1215-1233 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oligotripeptides Z-(Gly-Pro-Pro)n-OMe (n = 1,2,…,8), Z-Gly-Pro_Pro-Gly-Pro-Gly-OMe, Z-Gly-Pro-Pro-Gly-Pro-Gly-Gly-Pro-Pro-OMe, Z-Gly-Pro-Pro-(Gly-Pro-Gly)2-Gly-Pro-Pro-OMe, and Z-(Gly-Pro-Ala)n-OMe (n = 1,2,…,4) were synthesized step-by-step and then studied by means of x-ray diffraction, ir spectroscopy, the kinetics of hydrogen-deuterium exchange of peptide groups, and circular dichroism,. Different stages in the formation of a triple helix in Z-(Gly-Pro-Pro)n-OMe were revealed during the chain elongation. In the solid state, at the first stage a conformation of the polyproline II-type is formed in the tripeptide and in the second stage a triple helical complex appears in the hexapeptide. Interpeptide hydrogen bonds in this complex are still of low order. At further stages an ordered set of interpeptide hydrogen bonds is gradually formed. It is shown that the degree of order of interpeptide H bonds depends on the length of the molecular chain, the amino acid composition, and residue sequence in the triplets.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1978.360170509
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