Identification of cyanogen bromide peptides involved in intermolecular cross-linking of bovine type III collagen.

Cyanogn bromide peptides derived from bovine type III collagen and containing reducible cross-links were isolated and identified. Two peptides, alpha 1 (III)CB7 and alpha 1 (III)CB9B, from within the helical portion of the molecule were shown to contain the 'amino donor' residues cross-linked to non-helical 'aldehyde donor' residues in the formation of cross-links. This information, in conjunction with previously published data for the order of the cyanogen bromide peptides [Fietzek, Allman, Rauterberg & Wachter (1977) Proc. Natl. Acad. Sci. U.S.A. 74, 84-86], suggests that in type III collagen intermolecular cross-links are located in the end-overlap regions, so as to stabilize a quarter-stagger arrangement of molecules within the fibre in a similar manner to that proposed for type I and type II collagens.