Oxidation of methanol, ethylene glycol, and isopropanol with human alcohol dehydrogenases and the inhibition by ethanol and 4-methylpyrazole
Oxidation of methanol, ethylene glycol, and isopropanol with human alcohol dehydrogenases and the inhibition by ethanol and 4-methylpyrazole
复制标题
DOI：
10.1016/j.cbi.2010.12.005
复制
发表时间：
2011-05-30
影响因子：
5.1
通讯作者：
Yin, Shih-Jiun
中科院分区：
文献类型：
--
作者：
Lee, Shou-Lun;Shih, Hsuan-Ting;Yin, Shih-Jiun
人类乙醇脱氢酶(ADHS)包括多种同工酶，具有广泛的底物专一性和种族差异。ADH催化各种初级和次级脂肪醇代谢的限速步骤。人类ADHS对常见有毒酒精，即甲醇、乙二醇和异丙醇的氧化仍然知之甚少。动力学研究在0.1M磷酸二氢钠缓冲液中进行，pH 7.5，25℃，含有0.5 mM NAD(+)和不同浓度的底物。乙醇与重组人第I类ADH1A、ADH1B1、ADH1B2、ADH1B3、ADH1C1和ADH1C2以及第II类ADH2和第IV类ADH4的K-M值分别为0.12-57 mm、2.0-3500 mm、4.3-2600 mm和0.73-3400 mm。ADH1B3对乙二醇无活性，ADH2和ADH4对甲醇无活性。在ADH家族中，有毒醇类的V-max的变化比K-M的变化小得多。4-甲基吡唑(4MP)对ADH1a、ADH1B1、ADH1B2、ADH1C1和ADH1C2是乙醇竞争性抑制剂，对ADH1B3、ADH2和ADH4是非竞争性抑制剂，全家族的斜率抑制常数(K-IS)为0.062-960mU，截断抑制常数(K-II)为33-3000mM，用计算机模拟研究了乙醇替代底物和末端抑制剂4MP对ADH家族的抑制方程和相应的动力学参数。结果表明，20 mM乙醇或50 mU M4MP对50 mM以下的有毒醇类的氧化有较大的抑制作用，但有个别例外。以上研究结果为临床应用4MP或乙醇治疗甲醇、乙二醇中毒提供了药理学依据。(C)2010爱思唯尔爱尔兰有限公司。保留所有权利。
Human alcohol dehydrogenases (ADHs) include multiple isozymes with broad substrate specificity and ethnic distinct allozymes. ADH catalyzes the rate-limiting step in metabolism of various primary and secondary aliphatic alcohols. The oxidation of common toxic alcohols, that is, methanol, ethylene glycol, and isopropanol by the human ADHs remains poorly understood. Kinetic studies were performed in 0.1 M sodium phosphate buffer, at pH 7.5 and 25 degrees C, containing 0.5 mM NAD(+) and varied concentrations of substrate. K-M values for ethanol with recombinant human class I ADH1A, ADH1B1, ADH1B2, ADH1B3, ADH1C1, and ADH1C2, and class II ADH2 and class IV ADH4 were determined to be in the range of 0.12-57 mM, for methanol to be 2.0-3500 mM, for ethylene glycol to be 4.3-2600 mM, and for isopropanol to be 0.73-3400 mM. ADH1B3 appeared to be inactive toward ethylene glycol, and ADH2 and ADH4, inactive with methanol. The variations for V-max for the toxic alcohols were much less than that of the K-M across the ADH family. 4-Methylpyrazole (4MP) was a competitive inhibitor with respect to ethanol for ADH1A, ADH1B1, ADH1B2, ADH1C1 and ADH1C2, and a noncompetitive inhibitor for ADH1B3, ADH2 and ADH4, with the slope inhibition constants (K-is) for the whole family being 0.062-960 mu M and the intercept inhibition constants (K-ii), 33-3000 mu M. Computer simulation studies using inhibition equations in the presence of alternate substrate ethanol and of dead-end inhibitor 4MP with the determined corresponding kinetic parameters for ADH family, indicate that the oxidation of the toxic alcohols up to 50 mM are largely inhibited by 20 mM ethanol or by 50 mu M 4MP with some exceptions. The above findings provide an enzymological basis for clinical treatment of methanol and ethylene glycol poisoning by 4MP or ethanol with pharmacogenetic perspectives. (C) 2010 Elsevier Ireland Ltd. All rights reserved.