Amide I band of IR spectrum and structure of collagen and related polypeptides

The infrared amide I band of collagens (rat and cod skin) and related compounds (polyproline, polyglycine, and polytripeptides) was studied. Assignment of amide I‐band components for polyproline II and polytripeptides (Gly‐Pro‐Pro) n and (Gly‐Pro‐Gly) n in the solid state and water solution was made. Three amide I components observed in the polypeptide spectra were attributed to three different peptide CO groups in each triplet. On the basis of this assignment, the interpretation of the amide I multicomponent structure in collagen and isomorphous oligo‐ and polypeptides was attempted. The ordering of intra‐ and intermolecular hydrogen bonds involving peptide CO groups in collagen and related compounds was discussed.