The irreplaceable glycine: glycine homologs destabilize the collagen triple helix

Collagen, the most widespread protein in animals, contains glycine as every third amino acid. This regular repetition of glycine residues is required for the tight packing of the collagen triple helix. In this work, we substitute glycine with its homolog beta-alanine in collagen model peptides (CMPs) and study the effect of beta-alanine on the formation of triple helices. While beta-alanine in the middle of CMP sequences is incompatible with triple helix formation, terminal beta-alanine residues are tolerated. The work highlights the critical role of glycine in collagen.