MULTIPLE BINDING SITES OF HUMAN BRAIN AND LIVER MONOAMINE OXIDASE: SUBSTRATE SPECIFICITIES, SELECTIVE INHIBITIONS, AND ATTEMPTS TO SEPARATE ENZYME FORMS
MULTIPLE BINDING SITES OF HUMAN BRAIN AND LIVER MONOAMINE OXIDASE: SUBSTRATE SPECIFICITIES, SELECTIVE INHIBITIONS, AND ATTEMPTS TO SEPARATE ENZYME FORMS
复制标题
人脑和肝脏单胺氧化酶的多个结合位点：底物特异性、选择性抑制和分离酶形式的尝试
DOI：
10.1111/j.1471-4159.1977.tb06502.x
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发表时间：
1977
影响因子：
4.7
通讯作者：
Ann T. Glassman
中科院分区：
文献类型：
--
作者：
H. White;Ann T. Glassman
翻译后摘要-人的大脑和肝脏线粒体的单胺氧化酶溶解的程序，保留原线粒体制备的底物和抑制剂的选择性。设计用于基于分子大小或净表面电荷分离蛋白质的技术没有产生酶活性A和B形式的物理分离，即使在离子去污剂存在下或在有限的蛋白质水解下也是如此。然而，巯基抑制剂、无机盐、离子去污剂、热处理和超声处理均倾向于导致溶解制剂中5-羟色胺代谢活性的选择性失活。选择性抑制（膜结合或溶解）MAO的实验支持至少两种独立的底物结合位点的概念，其中只有一种代谢5-羟色胺（A型），另一种（B型）对β-苯乙胺具有很强的亲和力。l-去甲肾上腺素、色胺、多巴胺和酪胺可归类为常见底物。色胺在A位点和β-苯乙胺在B位点的Km值最低。这项研究的结果表明，不同的MAO网站可能是同一个大的分子复合物的一部分，这可能通常是嵌入在线粒体外膜，使A网站更依赖于他们的脂质环境在这个膜。
Abstract— MAO of human brain and liver mitochondria was solubilized by a procedure that preserved the substrate and inhibitor selectivities of the original mitochondrial preparation. Techniques that are designed to separate proteins on the basis of molecular size or net surface charge did not yield a physical separation of enzymically active A and B forms, even in the presence of ionic detergents or with limited proteolysis. However, sulfhydryl inhibitors, inorganic salts, ionic detergents, heat treatment, and sonication all tended to cause selective inactivation of serotonin‐metabolizing activity in solubilized preparations. Experiments with selectively inhibited (membrane‐bound or solubilized) MAO supported the concept of at least two independent kinds of substrate binding site, only one of which metabolizes serotonin (A type) and another (B type) which has a very strong affinity for β‐phenethylamine. l‐Norepinephrine, tryptamine, dopamine, and tyramine could be classified as common substrates. The lowest Km values were found for tryptamine at A sites and for β‐phenethylamine at B sites. Results of this study suggest that the different MAO sites could be part of the same large molecular complex, which may normally be embedded in the outer mitochondrial membrane so that A sites are more dependent on their lipid environment within this membrane.