Monoamine Oxidaseに関する研究-57-ヒト胎盤MAOに対する酸素濃度の影響
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概要
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The time courses of reaction rate, effect of oxygen concentration and effect of various reagents on human placental MAO were studied. Homogenate of human placenta was used as an enzyme source and MAO activity was measured by Warburg's manometer. Human placental MAO activity with β-phenylethylamine as substrate did not show any changes in activity for a long time from the start of reaction, but with serotonin, tryptamine, and tyramine as substrate it decreased markedly in the course of reaction time. MAO activity with β-phenylethylamine as substrate in 100% O<SUB>2</SUB> concentration as gas phase was three times higher than that of in 20% O<SUB>2</SUB> concentration. However, MAO activity with serotonin as substraet in 100% O<SUB>2</SUB> concentration as gas phase was only 1.5 times higher than that of in 20% O<SUB>2</SUB> concentration. MAO activity with β-phenylethylamine as substrate increased with the increase in O<SUB>2</SUB> concentration as gas phase almost linearly, while MAO activity with serotonin as substrate increased rapidly at 10-20% O<SUB>2</SUB> concentration and reached almost maximum velocity at 40% O<SUB>2</SUB> concentration. MAO activity with β-phenylethylamine as substrate was inhibited by catron more strongly than by harmaline, while MAO activity with serotonin as substrate was inhibited more strongly by catron. Catron showed a noncompetitive inhibition of MAO against O<SUB>2</SUB> when serotonin was used as substrate, but it showed a competitive inhibition of MAO against O<SUB>2</SUB> when β-phenylethylamine was used as substrate.
- 学校法人 昭和大学・昭和医学会の論文