Collagen Cross-Linking: The Substrate Specificity of Lysyl Oxidase

Abstract

Lysyl oxidase is a specific amine oxidase that contains copper and is irreversibly inhibited by compounds called lathyrogens (1,2,3). 3-Aminopropionitrile (BAPN) is the most widely studied and best known of these compounds. When growing animals are either fed lathyrogens or made copper deficient they develop a wide variety of connective tissue and skeletal abnormalities such as dissecting aneurysms of the thoracic aorta, kyphoscoliosis and abdominal hernias. The pathogenesis of these abnormalities is related to decreased collagen cross-linking secondary to decreased lysyl oxidase activity which results from either lack of the copper cofactor(4) or irreversible inhibition by BAPN. Since clinical abnormalities in these disorders have been noted as a result of deranged biosynthesis in both elastin and collagen with lysyl oxidase deficiency, it seemed appropriate to define the substrate specificity of highly purified lysyl oxidase in more detail and to determine whether the same enzyme is active on collagen and elastin substrates(5,6,7,8).