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Triple helix–coil transition of covalently bridged collagenlike peptides
Author(s) -
Roth Werner,
Heidemann Eckhart
Publication year - 1980
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.1980.360191017
Subject(s) - tripeptide , chemistry , isomerization , covalent bond , helix (gastropod) , triple helix , hydrogen bond , dynamic covalent chemistry , crystallography , nucleation , solvent , peptide , stereochemistry , molecule , organic chemistry , crystal structure , supramolecular chemistry , ecology , biochemistry , snail , biology , catalysis
The thermal triple helix–coil transition of covalently bridged collagenlike peptides with repeating sequences of (Ala‐Gly‐Pro) n , n = 5–15, was studied optically. The peptides were soluble in water/acetic acid (99:1) and were found to form triple‐helical structures in this solvent system beginning with n = 8. The thermodynamic analysis of the transition equilibrium curves for n = 9–13 yielded the parameters Δ H ° s = −7.0 kJ per tripeptide unit, Δ S ° s = −23.1 J deg −1 mol −1 per tripeptide unit for the coil‐to‐helix transition, and the apparent nucleation parameter σ ≃ 5 × 10 −2 . It was suggested through double‐jump temperature experiments that the rate‐limiting step during refolding is not only influenced by the difficulties of nucleation, but also by cis – trans isomerization of the Gly‐Pro peptide bond.