THE MOLECULAR LOCATION OF EHRLICH CHROMOGEN AND PYRIDINOLINE CROSS-LINKS IN BOVINE PERIMYSIAL COLLAGEN

Collagenous peptides containing the Ehrlich chromogen (EC), a trifunct ional cross-link of proposed pyrrolic structure, were selectively isol ated from a tryptic digest of bovine perimysial collagen by coupling t o a diazotised support. Peptides containing pyridinoline (Pyr), anothe r trifunctional cross-link but based on a 3-hydroxypyridinium ring, we re isolated from the uncoupled material. The isolated cross-linked pep tides were purified by chromatographic procedures and subsequently cha racterised by amino acid and sequence analyses. EC occurred in stoichi ometric amounts in three-chained peptides derived from type I collagen cross-link regions. In contrast, Pyr was found in non-stoichiometric amounts in three-chained peptides where two of the chains were identif ied as the 76 amino-terminal residues of the alpha1 (III) collagen cha in. The third chain in these Pyr cross-linked peptides was derived fro m the C-terminal helical cross-link region of either type III collagen or the corresponding region of type I collagen, with the former regio n predominating. These findings suggest that EC and Pyr cross-links of perimysial collagen are associated mainly with type I and type III co llagen respectively.