BIOSYNTHESIS OF COLLAGEN CROSSLINKS IN RABBIT ARTICULAR-CARTILAGE INVIVO

The biosynthesis in vivo of the two reducible aldimine crosslinks of immature rabbit articular collagen, hydroxylysinohydroxynorleucine and hydroxylysinonorleucine, is demonstrated. The peak amount of crosslink was detected 1-2 weeks following labeling of the cartilage with [14C]lysine. The subsequent diminution which occurred was due primarily to a decrease in the amount of hydroxylysinohydroxynorleucine. Natural reduction of the aldimine crosslinks in vivo did not occur. Glucosylgalactosyl hydroxylysine and galactosylhydroxylysine, in a 1.45 1.00 ratio, were synthesized. Seventy-three percent of the hydroxylysine residues were glycosylated. [3H]NaBH4 reduction of non-14C-labeled cartilage showed diminished amounts of reducible crosslink with time and the presence of hexosyl lysines and hexosyl hydroxylysines in mature articular cartilage. © 1979.