Mantle T J, Houslay M D, Garrett N J, Tipton K F
J Pharm Pharmacol. 1976 Sep;28(9):667-71. doi: 10.1111/j.2042-7158.1976.tb02833.x.
The activity of beef heart mitochondrial monoamine oxidase towards 5-hydroxytryptamine (5-HT) is inhibited by the selective inhibitors clorgyline, PCO [5-phenyl-3-(N-cyclopropyl)-ethylamine-1,2,4-oxidiazole] and Deprenyl with a biphasic dependence on the inhibitor concentration. The activities towards tyramine, dopamine and tryptamine were also inhibited in a biphasic manner, but the apparent proportions of the two enzyme species active on dopamine and tryptamine depended on the inhibitor used. Phenethylamine oxidation was inhibited in a monophasic manner suggesting that only a single enzyme species was responsible for the oxidation of this substrate. The biphasic response of 5-HT oxidation to inhibition by clorgyline persisted when functionally competent mitochondria were used and was unaffected by the soluble amine oxidase inhibitors semicarbazine and aminoguanidine. These results indicate that the behaviour of the beef heart enzyme towards selective inhibitors is considerably different from that of any preparations previously studied and suggest that the classification of monoamine oxidase activites into A and B types may be only of limited usefulness.
牛心线粒体单胺氧化酶对5-羟色胺（5-HT）的活性受到选择性抑制剂氯吉兰、PCO [5-苯基-3-（N-环丙基）-乙胺-1,2,4-恶二唑] 和司来吉兰的抑制，对抑制剂浓度呈双相依赖性。对酪胺、多巴胺和色胺的活性也呈双相抑制，但对多巴胺和色胺有活性的两种酶的明显比例取决于所使用的抑制剂。苯乙胺氧化呈单相抑制，表明只有单一酶负责该底物的氧化。当使用功能正常的线粒体时，5-HT氧化对氯吉兰抑制的双相反应持续存在，并且不受可溶性胺氧化酶抑制剂氨基脲和氨基胍的影响。这些结果表明，牛心酶对选择性抑制剂的行为与之前研究的任何制剂有很大不同，并表明将单胺氧化酶活性分为A和B型可能仅具有有限的用途。
