Reaction pathway of bovine aortic lysyl oxidase.
Reaction pathway of bovine aortic lysyl oxidase.
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DOI：
10.1016/s0021-9258(18)67681-1
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发表时间：
1986-07
期刊：
影响因子：
--
通讯作者：
P. Williamson;H. Kagan
中科院分区：
文献类型：
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作者：
P. Williamson;H. Kagan
赖氨酰氧化酶对胺氧化的催化作用已被探索，以评估底物结合和产物释放的可能顺序，并区分以前提出的以分子氧为底物的其他铜依赖胺氧化酶的机械替代方案。Lineweaver-Burk图显示，当正丁胺在不同固定氧气浓度下氧化时，呈现平行线模式，符合“乒乓”动力学机制，即醛在第二底物氧结合之前产生和释放。最初的猝发实验表明，在无氧条件下，赖氨酰氧化酶能够生成和释放与功能活性中心含量成化学计量比的正丁醛，这与乒乓球动力学一致。在一定浓度的反应产物存在下，正丁胺氧化反应的倒数图符合Uni-Bipong动力学机理，醛是第一位的，H_2O_2是第二位的，氨是最后的离位产物。此外，赖氨酰氧化酶氧化对羟基苄胺的光谱研究表明，该酶不会将胺底物处理为非共价结合的对羟基苯二胺中间体，然后再将其水解为对羟基苯甲醛。因此，赖氨酰氧化酶的动力学机制似乎与二胺氧化酶和猪血浆单胺氧化酶所描述的相似。
The catalysis of amine oxidation by lysyl oxidase has been probed to assess for the likely order of substrate binding and product release and to discriminate between mechanistic alternatives previously proposed for other copper-dependent amine oxidases using molecular oxygen as a substrate. Lineweaver-Burk plots revealed a pattern of parallel lines when the oxidation of n-butylamine was followed at different fixed concentrations of oxygen consistent with a "ping-pong" kinetic mechanism in which the aldehyde is produced and released before the binding of oxygen, the second substrate. Initial burst experiments revealed the ability of lysyl oxidase to form and release n-butyraldehyde in amounts stoichiometric with functional active site content in the absence of oxygen, consistent with the ping-pong kinetics obtained. Reciprocal plots of n-butylamine oxidation in the presence of fixed concentrations of the reaction products were consistent with a Uni Uni Uni Bi ping-pong kinetic mechanism with the aldehyde being the first, H2O2 the second, and ammonia the last departing product. Moreover, spectral studies of the oxidation of p-hydroxybenzylamine by lysyl oxidase indicated that the enzyme does not process the amine substrate to a noncovalently bound p-hydroxybenzaldimine intermediate subsequently to be hydrolyzed to p-hydroxybenzaldehyde. The kinetic mechanism of lysyl oxidase thus appears to be similar to those described for diamine oxidase and pig plasma monoamine oxidase.