Purification and partial amino acid sequence of a high-activity human stomach alcohol dehydrogenase.
Purification and partial amino acid sequence of a high-activity human stomach alcohol dehydrogenase.
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高活性人胃乙醇脱氢酶的纯化和部分氨基酸序列。
DOI：
10.1111/j.1530-0277.1993.tb00863.x
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Li,TK
中科院分区：
文献类型：
--
作者：
Stone,CL;Thomasson,HR;Bosron,WF;Li,TK
为了了解乙醇脱氢酶（ADH）同工酶在胃乙醇代谢中的相对重要性，从人移植供体和手术组织中纯化了胃特异性ADH（σ-ADH），并检查了其乙醇氧化活性。来自这些组织的酶在pH 10时的比活性为1070单位/mg，约为Moreno和Parés报道的比活性的10倍（J.Biol.Chem.266：1128-1133，1991）。该酶在pH 7.5和10时对乙醇有较高的Km值（分别为29和5.2mM）。这种高活性α-ADH同工酶在淀粉和等电聚焦凝胶上迁移到肝脏σ同工酶略微阳极的位置。用内切蛋白酶消化，并对约40%的蛋白质进行测序。σ-ADH与人I类（β1）、II类（π）和III类（χ）同工酶的序列同一性分别为75%、68%和62%，与推导的ADH 6氨基酸序列的同一性为61%。系统发育分析表明，这种高活性σ-ADH和I类同工酶的前体比II类和III类同工酶的前体分化得更晚，在爬行动物和鸟类分化之后。因此，高活性σ-ADH同工酶代表了ADH的一个独特类别（IV类），在进化上与I类同工酶的关系比与其他已知的人类同工酶更密切。
To understand the relative importance of alcohol dehydrogenase (ADH) isoenzymes in gastric ethanol metabolism, a stomach‐specific ADH (σ‐ADH) was purified to homogeneity from human transplant donor and surgical tissues, and its activity for ethanol oxidation was examined. The enzyme from these tissues had a specific activity at pH 10 of ˜70 units/mg, about 10 times that reported by Moreno and Parés (J. Biol. Chem.266:1128–1133, 1991). The enzyme exhibited a highKmfor ethanol at pH 7.5 and 10 (29 and 5.2 mM, respectively). This high‐activity α‐ADH isoenzyme migrated on starch and isoelectric focusing gels to a position slightly anodic to the liver σ isoenzyme. It was subjected to digestion by endoproteinases, and ˜40% of the protein was sequenced. The σ‐ADH exhibited 75%, 68%, and 62% sequence identity to the human class I (β1), II (π), and III (χ) isoenzymes, respectively, and 61% identity to the deduced ADH6 amino acid sequence. Phylogenetic analysis indicated that precursors to this high‐activity σ‐ADH and the class I isoenzymes diverged more recently than precursors to the class II and III isoenzymes, after reptilian and avian divergence. The high‐activity σ‐ADH isoenzyme therefore represents a distinct class of ADH (class IV), more closely related in evolution to the class I isoenzymes than to the other known human isoenzymes.