Kampa L, Peisach J
J Biol Chem. 1980 Jan 25;255(2):595-601.
An hydroxyindole oxidase has been purified 100-fold from the gill plates of Mytilus edulis. This preparation yields a single band on acrylamide gel electrophoresis and isoelectric focusing. Metal analysis and spectral data show that both heme iron and copper are present in the purified enzyme in a 1:1 molar ratio. Potassium cyanide, sodium azide, various copper chelators, and carbon monoxide inhibit the enzyme-catalyzed reaction. These inhibition studies, as well as the photoreversibility of the CO inhibition, lend support to the conclusion that metal ions function as necessary cofactors for substrate oxidation. The Mytilus gill enzyme oxidizes a variety of substrates, among them biogenic amines. For all substrates tested, 1 dioxygen molecule is consumed/mol of substrate oxidized. When p-coumaric acid is hydroxylated, caffeic acid is formed in quantitative yield. H2O2 has been identified as a second product of the oxidation reaction. The addition of catalase prior to the onset of reaction is inhibitory while H2O2 or ascorbate activate the enzyme. These findings suggest that the hydroxyindole oxidase may be a monooxygenase which does not require reduced pyridine nucleotide for reductive activation.
已从紫贻贝的鳃板中纯化出一种羟基吲哚氧化酶，纯化倍数达100倍。该制剂在丙烯酰胺凝胶电泳和等电聚焦中产生一条带。金属分析和光谱数据表明，纯化后的酶中血红素铁和铜的摩尔比为1:1。氰化钾、叠氮化钠、各种铜螯合剂和一氧化碳可抑制酶催化反应。这些抑制研究以及一氧化碳抑制的光可逆性支持了金属离子作为底物氧化必需辅因子发挥作用的结论。紫贻贝鳃酶可氧化多种底物，其中包括生物胺。对于所有测试的底物，每氧化1摩尔底物消耗1分子双原子氧。当对香豆酸被羟基化时，可定量生成咖啡酸。已确定过氧化氢是氧化反应的第二种产物。在反应开始前加入过氧化氢酶具有抑制作用，而过氧化氢或抗坏血酸可激活该酶。这些发现表明，羟基吲哚氧化酶可能是一种单加氧酶，不需要还原型吡啶核苷酸进行还原激活。
