Abstract
Lysyl oxidase is a specific amine oxidase that catalyzes the formation of aldehyde cross-link intermediates in collagen and elastin. In this study, lysyl oxidase from embryonic chick cartilage was purified to constant specific activity and a single protein band on sodium dodecyl sulfate acrylamide gel electrophoresis. This band had an apparent molecular weight of 62,000. The eluted protein cross-reacted with inhibiting antisera developed against highly purified lysyl oxidase. The highly purified enzyme was active with both insoluble elastin and embryonic chick skin or bone collagen precipitated as reconstituted, native fibrils. There was low activity with nonhydroxylated collagen, collagen monomers, or native fibrils isolated from lathyritic calvaria. The maximum number of aldehyde intermediates formed per molecule of collagen that became insoluble was two. These results indicate that lysyl oxidase has maximum activity on ordered aggregates of collagen molecules that may be overlapping associations of only a few collagen molecules across. Formation of aldehyde intermediates and cross-links during fibril formation may facilitate the biosynthesis of stable collagen fibrils and contribute to increased fibril tensile strength in vivo.
Highlights
Surgery, University of California, San Francisco, Lysyl oxidase is a specific amine oxidase that catalyzes the formation of aldehyde cross-link intermediates in collagen and elastin
Lysyl oxidase from embryonic chick cartilage was purified to constant specific activity and a single protein band on sodium dodecyl sulfate acrylamide gel electrophoresis
Lysyl oxidase was originally detected by a tritium release assay in which chick aorta elastin labeled with [6-3H]lysine in organ culture was used as a substrate [1]
Summary
University of California, San Francisco, Lysyl oxidase is a specific amine oxidase that catalyzes the formation of aldehyde cross-link intermediates in collagen and elastin. Lysyl oxidase from embryonic chick cartilage was purified to constant specific activity and a single protein band on sodium dodecyl sulfate acrylamide gel electrophoresis. Lysyl oxidase is a specific amine oxidase [1,2,3,4,5] that catalyzes the formation of c-aldehydes in collagen and elastin from certain lysyl and hydroxylysyl residues (Fig. 1) [6] These aldehydes, allysine’ and hydroxyallysine, are intermediates in formation of intra- and intermolecular cross-links. Enzyme activity with elastin substrates was found to be much higher than that with labeled collagen substrates [6] This was presumed due to the greater number of lysyl residues in elastin that participated in cross-linking. The activity of highly purified chick cartilage lysyl oxidase has been compared with both collagen and elastin substrates and the nature of the optimal collagen substrate further defined
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