Comparative molecular distribution of cross-link in bone and dentin collagen. Structure-function relationships.

Bone and dentin contain exclusively genetic Type I collagen. These collagens have identical amino acid sequences, cross-link precursors and cross-links yet serve different physiological functions. Complete tryptic digests of the intractable [3H]NaBH4-reduced demineralization collagen from bovine cortical bone and dentin have successfully been obtained. Chromatography of the tryptic peptides on Sephadex G-50 allowed separation of cross-link peptide fractions containing dihydroxylysinonorleucine. Chromatography of peptides of the same molecular weight distribution from each sample, which should contain identical peptides, yielded different chromatographic patterns on phosphocellulose. The phosphocellulose fractions containing the most abundant amounts of dihydroxylysinonorleucine were rechromatographed on DEAE-cellulose and yielded dissimilar profiles. It was concluded that the cross-link, dihydroxylysinonorleucine, has a different molecular distribution in bone and dentin collagen. The results demonstrate that the collagen derived from two different mineralized tissues, possess different micromolecular structures. These structural differences may be related to diverse physiological functions.