Evidence for the role of 4‐hydroxyproline localized in the third position of the triplet (Gly‐X‐Y) in adaptational changes of thermostability of a collagen molecule and collagen fibrils

An analysis of the available data on the thermostability and imino acid content of various collagens has shown that the change of the denaturation temperature (tm) of the collagen triple helix, as well as the temperature of hydrothermic shrinkage (ts) of collagen fibrils, depends on the number of hydroxyproline residues localized in the third position of the collagen triplet. This change does not depend on the content of proline and 3‐ and 4‐hydroxyproline localized in the second position of the triplet. Empiric equations have been obtained connecting tm and ts with the content of 4‐hydroxyproline. The results of the analysis are in good agreement with one of the collagen structure models recently proposed by the Ramachandran school.