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An examination of the basic hypothesis of Zimm–Bragg theory based on energy distributions of peptide chains
Author(s) -
Jacchieri Saul G.
Publication year - 1992
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560440722
Subject(s) - chemistry , hydrogen bond , helix (gastropod) , conformational isomerism , nucleation , crystallography , peptide , alanine , thermodynamics , chemical physics , physics , molecule , amino acid , ecology , biochemistry , organic chemistry , snail , biology
Abstract Energy distributions of six alanine‐based peptides were generated by combining backbone and sidechain rotamers with a matrix algorithm and by classifying the obtained chain conformations in order of increasing energy. The interaction range was varied from 3 to 6 to allow a maximum of two contiguous i , i +4 hydrogen bonds. An examination of these results has shown an agreement between the energy distributions of the interaction intervals of the lysine residues located in positions 7, 12, and 17 and the basic hypothesis of Zimm–Bragg Theory. It was found, however, that the alanine residues have energy distributions in which the α‐helix is the preferred conformation even when a single i , i +4 hydrogen bond is formed so that α‐helix nucleation beginning with these residues is noncooperative. As a consequence, instead of being an all or nothing process, the helix–coil transition of short peptide chains should have the participation of small stretches of α‐helix and the nucleation (σ) and stabilization ( s ) parameters of Zimm–Bragg theory should have values larger than those determined by host–guest experiments. © 1992 John Wiley & Sons, Inc.