An 'affinity' method for preparing polypeptides enriched in the collagen-associated Ehrlich chromogen.

The collagen-associated compound which reacts at room temperature with acid dimethylaminobenzaldehyde (Ehrlichs reagent) also reacts in acid with aryl-diazonium reagents. We have developed a convenient method for isolating polypeptides associated with the Ehrlich chromogen from collagen digests utilizing diazotized arylamino-cellulose supports. These peptides, in which the Ehrlich chromogen is 'labeled' with yellow diazo color, constitute less than 0.5% of the collagen, and have amino acid patterns similar to those around the cross link regions. The chromogen is not identical with pyridinoline, also thought to be a polyvalent cross link.