title: The organization of cross-linking in collagen fibrils.
abstract: The cross-linked peptides in cyanogen bromide digests from rabbit and calf fibrils of type I collagen have been compared by gel filtration and electrophoresis. Fibrils were prepared in vitro from acid-soluble collagen, or tendons were used; both were reduced with borohydride to stabilize cross-linking adducts. The cross-linked peptides were isolated and hydrolyzed, and the reducible cross-links were analyzed. We propose that a prominent pattern of cross-linking involves in-register palisades of molecules overlapping by 27 nm and joined through the condensation of amino-terminal aldol adducts on the carboxy-terminal helical regions of overlapping molecules. Lateral association probably occurs through the carboxy-terminal aldehydes from two molecules forming tri- or quadrivalent adducts with residues in the overlapped molecule. This model favors the recently proposed quasi-hexagonal organization of molecules in fibrils in which rows of molecules occur in lateral register.
mesh_terms: D000818:Animals; D002417:Cattle; D003094:Collagen; D003238:Connective Tissue / Q000648:ultrastructure*; D046911:Macromolecular Substances; D008970:Molecular Weight; D010446:Peptide Fragments / Q000032:analysis; D011817:Rabbits; D013710:Tendons / Q000648:ultrastructure
chemical_list: D046911:Macromolecular Substances; D010446:Peptide Fragments; D003094:Collagen