Abstract
A number of synthetic polypeptides are known to undergo “inverse” thermal helix–coil transitions in solvent mixtures containing an “active” solvent such as dichloroacetic acid (DCA). A statistical mechanical theory of the effects of the active component on the transition is developed here on the assumption that the active solvent exists in the form of a dimer and that the dimerized molecules react with pairs of CO and NH groups of randomly coiled peptide units. Expressions are derived for the equilibrium constant, u, of helix formation and the cooperativity parameter, σ, and they are used to analyze data obtained for poly(γ-benzyl-L-glutamate) and poly(β-benzyl-L-aspartate) in mixtures of DCA and ethylene dichloride as functions of temperature and solvent composition. The values of the transition parameters so determined make it possible to understand not only why and how the observed values of transition enthalphy ΔH and cooperativity parameter σ depend on temperature and solvent composition, but also the general features of inverse transitions in quantitative terms. An important conclusion is that σ is profoundly affected by the binding of the active solvent on the polypeptide chain.
Similar content being viewed by others
Article PDF
References
G. D. Fasman, in “Poly-α-Amino Acids,” G. D. Fasman, Ed., Marcel Dekker, Inc., New York, N. Y., 1967, Chapter 11.
P. Doty, and J. T. Yang, J. Am. Chem. Soc., 78, 498 (1956).
J. A. Schellman, Compt. Rend. Trav. Lab. Carlsberg, Ser. Chim., 29, 230 (1955).
J. A. Schellman, J. Phys. Chem., 62, 1485 (1958).
L. Peller, J. Phys. Chem., 63, 1194 (1959).
L. Peller, J. Phys. Chem., 63, 1199 (1959).
J. H. Gibbs and E. A. DiMarzio, J. Chem. Phys., 30, 271 (1959).
M. Bixon and S. Lifson, Biopolymers, 4, 815 (1966).
G. C. Pimentel and A. L. McClellan, ”The Hydrogen Bond,” Freemen & Co., San Francisco and London, 1959.
K. Nagai, J. Chem. Phys., 34, 887 (1961).
B. H. Zimm and J. K. Bragg, J. Chem. Phys., 31, 526 (1959).
K. Okita, A. Teramoto, and H. Fujita, Biopolymers, 9, 111 (1970).
Y. Hayashi, A. Teramoto, K. Kawahara, and H. Fujita, Biopolymers, 8, 403 (1969).
T. Norisuye, M. Matsuoka, A. Teramoto, and H. Fujita, Polym. J., 1, 691 (1970).
A. Teramoto, unpublished data.
“Organic Solvents,” A. Weissberger, E. S. Proskauer, J. A. Riddick, and E. E. Toops, Jr., Ed., Interscience Publishers, Inc., New York, N. Y., 1955, p 196.
A. Nakajima and T. Hayashi, Bull. Inst. Chem. Res., Kyoto Univ., 46, 62 (1968).
A. Teramoto and T. Norisuye, Biopolymers, in press.
R. T. Ingwall, H. A. Scheraga, N. Lotan, A. Berger, and E. Katchalsky, Biopolymers, 6, 331 (1968).
J. T. Yang, Tetrahedron, 13, 143 (1961).
P. J. Flory, “Principles of Polymer Chemistry,” Cornell Univ. Press, Ithaca, N.Y., 1953.
T. Norisuye, A. Teramoto, and H. Fujita, to be published in Polym. J.
F. Gaskin and J. T. Yang, Biopolymers, 10, 631 (1971).
F. E. Karasz and J. M. O’Reilly, Biopolymers, 3, 241 (1965).
M. Go, N. Go, and H. A. Scheraga, J. Chem. Phys., 52, 2060 (1970).
M. Go, N. Go, and H. A. Scheraga, J. Chem. Phys., 54, 4489 (1971).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Sayama, N., Kida, K., Norisuye, T. et al. Solution Properties of Synthetic Polypeptides. XI. Solvent Effect on Helix–Coil Transition in Polypeptides. Polym J 3, 538–550 (1972). https://doi.org/10.1295/polymj.3.538
Issue Date:
DOI: https://doi.org/10.1295/polymj.3.538
Keywords
This article is cited by
-
Thermodynamic aspects of conformational transitions in synthetic polypeptides
Journal of Thermal Analysis (1976)