Yin S J, Wang M F, Liao C S, Chen C M, Wu C W
Department of Biochemistry, National Defense Medical Center, Taipei, Taiwan, Republic of China.
Biochem Int. 1990 Dec;22(5):829-35.
A new form of alcohol dehydrogenase, designated mu-alcohol dehydrogenase, was identified in surgical human stomach mucosa by isoelectric focusing and kinetic determinations. This enzyme was anodic to class I (alpha, beta, gamma) and class II (pi) alcohol dehydrogenases on agarose isoelectric focusing gels. The partially purified mu-alcohol dehydrogenase, specifically using NAD+ as cofactor, catalyzed the oxidation of aliphatic and aromatic alcohols with long chain alcohols being better substrates, indicating a barrel-shape hydrophobic binding pocket for substrate. mu-Alcohol dehydrogenase stood out in high Km values for both ethanol (18 mM) and NAD+ (340 microM) as well as in high Ki value (320 microM) for 4-methylpyrazole, a competitive inhibitor for ethanol. mu-Alcohol dehydrogenase may account for up to 50% of total stomach alcohol dehydrogenase activity and appeared to play a significant role in first-pass metabolism of ethanol in human.
通过等电聚焦和动力学测定，在手术切除的人胃黏膜中鉴定出一种新形式的乙醇脱氢酶，命名为μ-乙醇脱氢酶。在琼脂糖等电聚焦凝胶上，这种酶相对于I类（α、β、γ）和II类（π）乙醇脱氢酶呈阳极迁移。部分纯化的μ-乙醇脱氢酶特异性地以NAD⁺作为辅因子，催化脂肪族和芳香族醇的氧化反应，长链醇是更好的底物，这表明其具有一个桶状的疏水底物结合口袋。μ-乙醇脱氢酶的乙醇Km值（18 mM）和NAD⁺ Km值（340 μM）都很高，对乙醇的竞争性抑制剂4-甲基吡唑的Ki值（320 μM）也很高。μ-乙醇脱氢酶可能占胃乙醇脱氢酶总活性的50%，并且似乎在人体乙醇的首过代谢中发挥重要作用。
