Monoamine Oxidaseに関する研究-53-混合基質実験による牛肝,牛脳およびヒト胎盤MAOの酵素化学的性質について

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The multiplicity and enzymic properties of MAO in mitochondria from bovine brain, liver and human placenta were investigated with method of the mixed substrates of tyramine, 5-HT and benzylamine. MAO activity was measured using Warburg's manometric method. Specific activities and PS curves of MAO in those organs were observed to be striking differences among the above three substrates. In the mixed substrates experiment in these organs, tyramine oxidation was competitively inhibited by benzylamine added to the reaction mixture, while 5-HT did not affect the oxidation. On the contrary, tyramine and 5-HT did not show any inhibitory effects on the benzylamine oxidation. In bovine brain and human placenta, however, 5-HT oxidation was inhibited by benzylamine and in human placenta, 5-HT oxidation was also inhibited by tyramine. The results obtained in this experiment indicated that MAO in those three organs might have multiple functional sites or at least two enzymes being in their different ratio in those organs. Namely, it is considered that benzylamine and tyramine are oxidatively deaminated on a common active site respectively, but 5-HT on any other active site than having an affinity for them.
学校法人昭和大学・昭和医学会の論文