Low‐energy conformations of two lysine‐containing tetrapeptides of collagen: Implications for posttranslational lysine hydroxylation

Abstract The possible role of conformational constraints in the posttranslational hydroxylation of lysyl residues in collagen has been investigated by means of conformational energy computations for the N‐acetyl‐N′‐methylamides of the four tetrapeptides Ala‐Xxx‐Gly‐Ser and Gly‐Xxx‐Ala‐Gly, where Xxx = Lys or Ala. When hydration is taken into account, all four peptides are shown to exist as a mixture of conformations, but there is a strong preference for type II bends in the conformational ensembles of two Ala‐Xxx‐Gly‐Ser tetrapeptides and for type I bends in the conformational ensembles of the other two. The results agree with experimental evidence suggesting that a type II bend is an important conformation for Ac‐Ala‐Lys‐Gly‐Ser‐NHCH 3 , and they support an earlier suggestion that a β‐bend may play a role in the posttranslational hydroxylation of Lys residues in position Y of the Gly‐X‐Y triplet in collagen.