CHARACTERIZATION OF 3 ISOENZYMES OF RAT ALCOHOL-DEHYDROGENASE - TISSUE DISTRIBUTION AND PHYSICAL AND ENZYMATIC-PROPERTIES
CHARACTERIZATION OF 3 ISOENZYMES OF RAT ALCOHOL-DEHYDROGENASE - TISSUE DISTRIBUTION AND PHYSICAL AND ENZYMATIC-PROPERTIES
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DOI：
10.1111/j.1432-1033.1987.tb10559.x
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发表时间：
1987-01-02
期刊：
影响因子：
--
通讯作者：
PARES, X
中科院分区：
文献类型：
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作者：
JULIA, P;FARRES, J;PARES, X
大鼠组织含有三种不同的乙醇脱氢酶（ADH）同工酶，我们将其命名为ADH-1、ADH-2和ADH-3。ADH-1是一种阳极同工酶，大量存在于眼组织、胃和肺中。ADH-2也是阳极的，并且在所有检查的大鼠器官中均被发现。ADH-3是一组阴极ADH形式，主要存在于肝脏中，是大多数大鼠ADH先前研究的主题。这三种同工酶已被纯化至均一并进行了表征。它们都具有相似的物理特性：Mr 80 000，有两个Mr 40 000的亚基;它们每个分子含有四个Zn原子，并且优选NAD+作为辅因子。然而，等电点不同：ADH-1为5.1，ADH-2为5.95-6.3，ADH-3为8.25-8.4。ADH-3对乙醇的Km为1.4mM，具有广泛的底物特异性，并被吡唑强烈抑制（Ki = 0.4 μ M）。ADH-2显示对长链醇和醛的底物特异性，不能被乙醇饱和，并且实际上对吡唑不敏感（Ki = 78.4 mM）。ADH-1具有中等性质，对乙醇的Km为340 mM，广泛的底物特异性和对吡唑的Ki为0.56 mM。大鼠ADH-1、ADH-2和ADH-3分别与人ADH II、III和I类表现出许多类似性。大鼠ADH同工酶的特异性定位和动力学特性表明，ADH-1和ADH-3可能作为代谢障碍，以外部醇和醛，而ADH-2可能有功能的内源性长链醇和醛的代谢。
Rat tissues contain three different isoenzymes of alcohol dehydrogenase (ADH) that we have named ADH-1, ADH-2 and ADH-3. ADH-1 is an anodic isoenzyme present in high amounts in the ocular tissues, stomach and lung. ADH-2 is also anodic and has been found in all the rat organs examined. ADH-3 is the group of cathodic ADH forms, mainly present in liver, that has been the subject of the majority of the previous studies on rat ADH. The three isoenzymes have been purified to homogeneity and characterized. All of them have similar physical characteristics: Mr 80 000, with two subunits of Mr 40 000; they contain four atoms of Zn per molecule, and prefer NAD+ as cofactor. Isoelectric points are, however, different: 5.1 for ADH-1, 5.95-6.3 for ADH-2 and 8.25-8.4 for ADH-3. ADH-3 exhibits a Km for ethanol of 1.4 mM, a broad substrate specificity and is strongly inhibited by pyrazole (Ki = 0.4 .mu.M). ADH-2 shows substrate specificity toward long-chain alcohols and aldehydes, cannot be saturated by ethanol and is practically insensitive to pyrazole (Ki = 78.4 mM). ADH-1 has intermediate properties, with a Km for ethanol of 340 mM, a broad substrate specificity and Ki for pyrazole of 0.56 mM. Rat ADH-1, ADH-2 and ADH-3 exhibit many analogies with human ADH classes II, III and I respectively. The specific localization and kinetic properties of rat ADH isoenzymes suggest that ADH-1 and ADH-3 may act as metabolic barriers to external alcohols and aldehydes whereas ADH-2 may have a function in the metabolism of the endogenous long-chain alcohols and aldehydes.