Li T K, Bosron W F, Dafeldecker W P, Lange L G, Vallee B L
Proc Natl Acad Sci U S A. 1977 Oct;74(10):4378-81. doi: 10.1073/pnas.74.10.4378.
HUMAN LIVER ALCOHOL DEHYDROGENASE (ALCOHOL: NAD(+) oxidoreductase, EC 1.1.1.1), homogeneous by physicochemical criteria, has been available in quantity only recently [Lange, L. G. & Vallee, B. L. (1976) Biochemistry 15, 4681-4686]. Until now, the biochemical basis of human alcohol metabolism had to be extrapolated from the properties and behavior of enzymes from other species, primarily horses and yeast. The biological determinants of human alcoholism have remained obscure, although recent evidence indicates a genetic predisposition, requiring delineation. A functionally distinct form of human liver alcohol dehydrogenase (ADH), which we have designated II-ADH, is provocative since, thus far, it seems to be unique to human beings. It has a high K(m) for ethanol and is remarkably insensitive (apparent K(I), 500 muM) to pyrazole and its derivatives, which are usually potent ADH inhibitors (K(I), 1 muM), a property that is the basis for the isolation of II-ADH. The affinity resin 4-[3-(N-6-aminocaproyl)aminopropyl]pyrazole-Sepharose binds all other known forms of ADH but not II-ADH, thereby separating it selectively by affinity chromatography. In turn, this has led to the establishment of its identity with that enzyme form which was previously known as the anodic band and characterized by a high K(m) for ethanol (20 mM at pH 7.5). The remarkable insensitivity of II-ADH to pyrazole inhibition has also permitted quantitation of its role in hepatic ethanol oxidation. At 5 mM ethanol, a saturating concentration for virtually all other forms of ADH, II-ADH contributes less than 15% to total ethanol oxidation. However, at intoxicating concentrations, e.g., 60 mM, it can account for as much as 40% of the total ethanol oxidation rate of liver, indicating a seemingly unique role for this enzyme form in ethanol elimination. Thus far, we have found the amount of II-ADH varies from liver to liver of individuals and is considerably more labile than the other molecular forms, phenomena whose inter- or independence requires further study. The isolation of human II-ADH advances efforts to recognize and understand biochemical mechanisms that may be biological determinants of alcoholism and alcohol-related disease states, now generally approached and managed largely as psychosocial disorders.
人肝脏乙醇脱氢酶（乙醇：NAD(+)氧化还原酶，EC 1.1.1.1），根据物理化学标准为均一的，直到最近才能够大量获得[兰格，L.G.和瓦利，B.L.（1976年）《生物化学》15，4681 - 4686]。在此之前，人类酒精代谢的生化基础不得不从其他物种（主要是马和酵母）的酶的性质和行为进行推断。人类酒精中毒的生物学决定因素一直不清楚，尽管最近的证据表明存在遗传易感性，这需要进行描述。一种功能上不同的人肝脏乙醇脱氢酶（ADH）形式，我们将其命名为II - ADH，具有启发性，因为到目前为止，它似乎是人类特有的。它对乙醇的K(m)值较高，并且对吡唑及其衍生物（通常是有效的ADH抑制剂，K(I)为1 μM）具有显著的不敏感性（表观K(I)为500 μM），这一特性是分离II - ADH的基础。亲和树脂4 - [3 - (N - 6 -氨基己酰基)氨基丙基]吡唑 - 琼脂糖能结合所有其他已知形式的ADH，但不结合II - ADH，从而通过亲和色谱法将其选择性分离。相应地，这导致确定了它与先前被称为阳极带且以对乙醇的高K(m)值（pH 7.5时为20 mM）为特征的酶形式相同。II - ADH对吡唑抑制的显著不敏感性也使得能够对其在肝脏乙醇氧化中的作用进行定量。在5 mM乙醇（几乎是所有其他形式ADH的饱和浓度）时，II - ADH对总乙醇氧化的贡献小于15%。然而，在中毒浓度（例如60 mM）下，它可占肝脏总乙醇氧化速率的高达40%，表明这种酶形式在乙醇消除中似乎具有独特作用。到目前为止，我们发现II - ADH的量在个体的肝脏之间有所不同，并且比其他分子形式更不稳定，这些现象之间的相互关系或独立性需要进一步研究。人II - ADH的分离推动了对可能是酒精中毒和酒精相关疾病状态的生物学决定因素的生化机制的认识和理解，目前这些疾病通常主要作为心理社会障碍来处理和管理。
