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The molecular basis of the temperature‐ and pH‐induced conformational transitions in elastin‐based peptides
Author(s) -
Li Bin,
Daggett Valerie
Publication year - 2003
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.10204
Subject(s) - chemistry , elastin , hydrogen bond , peptide , side chain , polar , hydrophobic effect , inverse temperature , crystallography , molecular dynamics , stereochemistry , organic chemistry , computational chemistry , polymer , molecule , thermodynamics , biochemistry , medicine , physics , pathology , astronomy
Elastin undergoes an inverse temperature transition and collapses at high temperatures in both simulation and experiment. We investigated a pH‐dependent modification of this transition by simulating a glutamic acid (Glu)‐substituted elastin at varying pHs and temperatures. The Glu‐substituted peptide collapsed at higher temperature than the unsubstituted elastin when Glu was charged. The charge effects could be reversed by neutralization of the Glu carboxyl groups at low pH, and in that case the peptide collapsed at a lower temperature. The collapse was accompanied by the formation of β‐turns and short distorted β‐sheets. Formation of contacts between hydrophobic side chains drives the collapse at high temperature, but interactions between water and polar groups (Glu and main chain) can attenuate this effect at high pH. The overall competition and balance of the polar and nonpolar groups determined the conformational states of the peptide. Water hydration contributed to the conformational transition, and the peptide and its hydration shell must be considered. Structurally, waters near polar residues mainly formed hydrogen bonds with the protein atoms, while waters around the hydrophobic side chains tended to be parallel to the peptide groups to maximize water–water interactions. © 2002 Wiley Periodicals, Inc. Biopolymers 68: 121–129, 2003