Collagen cross-linking. Synthesis of collagen cross-links in vitro with highly purified lysyl oxidase.
In this paper, the synthesis of collagen cross-links in vitro was investigated in a defined system consisting of highly purified chick cartilage lysyl oxidase and chick bone collagen fibrils. Cross-link synthesis in vitro was quite similar to the biosynthesis of collagen cross-links in vivo. Enzyme-dependent synthesis of cross-link intermediates and cross-linked collagen derived from lathyritic collagen occurred. The concentration of the two principal reducible cross-links, N6:6'-dehydro-5,5'-dihydroxylysinonorleucine and N6:6'-dehydro-5-hydroxylysinonorleucine, increased to a peak value of approximately two cross-links per molecule and then decreased. Synthesis of histidinohydroxymerodesmosine and a second polyfunctional cross-link of unknown structure began after synthesis of bifunctional cross-links was largely completed and proceeded linearly afterwards. Inhibition of lysyl oxidase after the bulk of bifunctional cross-link synthesis had occurred did not alter the rate of decrease in reducible cross-link concentration but did inhibit further histidinohydroxymerodesmosine synthesis. These results indicate that lysyl oxidase and collagen fibrils are the only macromolecules required for cross-link biosynthesis in vivo. It is likely that the decrease in reducible cross-links observed during fibril maturation results from spontaneous reactions within the collagen fibril rather than additional enzymatic reactions.
D000594:Amino Acid Oxidoreductases / Q000378:metabolism; D000596:Amino Acids / Q000032:analysis; D000629:Aminopropionitrile / Q000494:pharmacology; D000818:Animals; D001665:Binding Sites; D001842:Bone and Bones; D002356:Cartilage; D002642:Chick Embryo; D003094:Collagen; D007700:Kinetics; D046911:Macromolecular Substances; D011485:Protein Binding; D008249:Protein-Lysine 6-Oxidase / Q000378:metabolism
D000596:Amino Acids; D046911:Macromolecular Substances; D000629:Aminopropionitrile; D003094:Collagen; D000594:Amino Acid Oxidoreductases; D008249:Protein-Lysine 6-Oxidase