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A statistical mechanical study of helix–coil transition in concentrated solutions of polypeptides and proteins
Author(s) -
Maleev V. Ya.,
Gasan A. I.
Publication year - 1974
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1974.360131202
Subject(s) - chemistry , globular protein , macromolecule , enthalpy , thermodynamics , statistical mechanics , hydrogen bond , amide , helix (gastropod) , condensation , saturation (graph theory) , crystallography , organic chemistry , molecule , physics , ecology , biochemistry , mathematics , combinatorics , biology , snail
The helix–coil transition in polypeptides was studied by methods of statistical mechanics, taking account of interaction between “melted” amide groups through hydrogen bonds. The statistical sums are calculated in the explicit form for two limit cases: (1) the dilute solution when the main contribution is given by collisions of two particles; (2) “condensation” when contacting macromolecules form a united aggregate. In the first case the transition enthalpy was shown to decrease linearly when the concentration increases, while at the appropriate choice of theoretical parameters, melting temperature and range are almost independent of the concentration. In the second case the structural transition parameters were shown to be independent of the concentration (the saturation effect). These results agree with the experimental data on synthetic polypeptides reported by other authors and with data on some globular proteins (serum and egg albumin) reported in this paper.