Monoamine Oxidaseに関する研究-86-家兎肝臓mitochondria MAOの複数性,特に酸素に対する親和性から
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In order to know the enzymic character of mitochondrial monoamine oxidase (MAO) in rabbit liver, substrate specificities, effects of oxygen concentration and several inhibitors on MAO were studied. MAO in rabbit liver could oxidize tyramine most strongly, coming β-phenylethylamine (PEA) in the next, while the oxidation of 5-hydroxytryptamine (5-HT) was weakest among the substrates examined. Deprenyl and pargyline, specific inhibitors for type B MAO, strongly inhibited MAO activities with all substrates examined but clorgyline, a specific inhibitor for tyre A MAO, inhibited MAO in rabbit liver very little with any substrate used. From differences of affinity for oxygen, the mitochondrial MAO in rabbit liver could be divided into three groups unrelated to type A and B MAO. In the case of benzylamine, amylamine, 5-HT and butylamine as substrate, the affinity of MAO for oxygen was found to be high, while the affinity was very low with PEA and hexylamine as substrate. The affinity for oxygen obtained with tyramine and tryptamine as substrate was situated between those obtained with benzylamine and PEA. The order of affinity of MAO for oxygen was not relate to that of substrate specificity. The affinity for oxygen of MAO in rabbit liver was not changed by the addition of MAO inhibitors, such as clorgyline, deprenyl and pargyline. From these results, in regard to substrate specificities to MAO inhibitors, clorgyline, deprenyl and pargyline, it was suggested that the mitochondrial MAO in rabbit liver mainly consisted of type B MAO, but in regard to the affinity of MAO for oxygen, this enzyme could be composed three different forms.
- 学校法人 昭和大学・昭和医学会の論文