Incorporation of N-Glycine Residues Into Collagen to Form Salt Bridges

Collagen, the principal structural protein in mammals, adopts a right-handed triple helix composed of three left-handed polyproline-II helical polypeptide chains featuring repeating Gly-Xaa-Yaa tripeptide motifs. Positions Xaa and Yaa frequently contain charged amino acids, which can form salt bridges to stabilize the collagen triple-helical conformation and fibril formation. Over the past decades, researchers have exploited the charged amino acids to engineer salt bridges for constructing stable collagen-based biomaterials. However, the use of amino acid analogues to form salt bridges remains largely unexplored. Herein, we report for the first time the incorporation of charged N -gly residues into host-guest collagen mimetic peptides (CMPs) to establish salt bridges. Among these, the EGNap CMP exhibited the highest T m value of 48.2°C, marginally lower than that of the OGP sequence. Molecular modeling indicates that the N -gly can form salt bridges with the amino acid, but the distance of these salt bridges is greater than that of KGD. These findings establish a foundational strategy for leveraging N -gly-mediated electrostatic interactions in collagen engineering. Graphical Substitution of an N-gly residue at the Xaa position and an amino acid residue with the opposite charge at the Yaa position in a collagen mimetic peptide results in weaker salt bridges than in the KGD sequence but stronger than DGK, destabilizing the triple helix.