人类大脑的多元醇途径酶。醛糖还原酶和己糖酸脱氢酶的部分纯化及性质
Polyol-pathway enzymes of human brain. Partial purification and properties of aldose reductase and hexonate dehydrogenase.
作者信息
O'Brien M M, Schofield P J
出版信息
Biochem J. 1980 Apr 1;187(1):21-30. doi: 10.1042/bj1870021.
Aldose reductase and hexonate dehydrogenase were isolated from human brain and partially purified. The two enzymes exhibited distinctive substrate-specificity profiles with a variety of aldoses,and aliphatic and aromatic aldehydes. Aldose reductase exhibited a high affinity for DL-glyceraldehyde (Km of 62 microM) and a low affinity (Km of 90 mM) for glucose, the physiological substrate of the polyol pathway. Hexonate dehydrogenase exhibited a relatively low affinity for D-glucuronate (Km of 4.6 mM) and a very low affinity for glucose (Km of 390 mM). Both enzymes exhibited a high specificity for NADPH, and both were inhibited competitively by NADP+. Hexonate dehydrogenase was inhibited by iodoacetate, iodoacetamide, N-ethylmaleimide and p-chloromercuribenzoate. Preincubation with 2-mercaptoethanol resulted in activation. Both enzymes were inhibited by a number of barbiturates (barbital, phenobarbital and pentobarbital) and by the central-nervous-system drugs diphenylhydantoin and ethosuccinimide. The substrate specificity and pattern of inhibition suggest that the two enzymes isolated correspond to two of four previously reported aldehyde reductases isolated from human brain.
从人脑中分离并部分纯化了醛糖还原酶和己糖酸脱氢酶。这两种酶对多种醛糖、脂肪族醛和芳香族醛表现出独特的底物特异性谱。醛糖还原酶对DL-甘油醛具有高亲和力（Km为62μM），而对多元醇途径的生理底物葡萄糖具有低亲和力（Km为90mM）。己糖酸脱氢酶对D-葡萄糖醛酸具有相对较低的亲和力（Km为4.6mM），对葡萄糖具有非常低的亲和力（Km为390mM）。两种酶对NADPH均表现出高特异性，并且均被NADP +竞争性抑制。己糖酸脱氢酶被碘乙酸盐、碘乙酰胺、N-乙基马来酰亚胺和对氯汞苯甲酸抑制。与2-巯基乙醇预孵育导致激活。两种酶均被多种巴比妥类药物（巴比妥、苯巴比妥和戊巴比妥）以及中枢神经系统药物苯妥英和乙琥胺抑制。底物特异性和抑制模式表明，分离出的这两种酶对应于先前报道的从人脑中分离出的四种醛还原酶中的两种。
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