Influence of different tripeptides on the stability of the collagen triple helix. I. Analysis of the collagen sequence and identification of typical tripeptides

The amino acid sequence of the collagen α1(I) chain (calf) is analyzed. Deviations of random tripeptide distribution leads to the definition of clusters. Inside these regions, collagen-typical tripeptides are located. Besides Gly-Pro-Hyp, Gly-Pro-Ala, and Gly-Ala-Hyp, the polar sequences Gly-Glu-Hyp, Gly-Ala-Arg, Gly-Glu-Arg, and Gly-Pro-Lys form typical sequences. The neighborhood of each tripeptide is analyzed and classified. The proximity to the collagen-typical tripeptides is registered. Cluster theory: Less-typical sequences also fold as members of the collagen triple helix and they are as reasonable as well as important for the collagen structure as the cluster tripeptides, but only the latter are important for the nucleation of the triple-helical folding.