Collagen Triple Helix: Stability

Abstract Collagens are the most abundant extracellular matrix proteins in multicellular animals. They all contain a name‐giving collagen triple helix, which connects their three chains and varying amounts of other noncollagenous protein domains. To form the triple helix a repeated sequence of ‐Gly‐Xaa‐Yaa‐ is required, where Xaa and Yaa can be any residue. Each chain forms a polyproline‐II like left‐handed helix. The three chains are staggered by one residue from each other, and form a right‐handed helix. Twenty eight types of collagen molecules have been identified in mammals. The stability of the collagen triple helix is based on the length and the amino acid sequence of each polypeptide chain, and also by the presence of interchain cross‐links and/or trimerization domains. The 4(R)‐hydroxylation of proline residues in the Yaa position significantly increases the stability of the collagen triple helix.