Dickenson C J, Dickinson F M
Biochem J. 1976 Feb 1;153(2):309-19. doi: 10.1042/bj1530309.
Alcohol dehydrogenase was partially purified from yeast (Saccharomyces cerevisiae) grown in the presence of 20 muM-MnSO4 without added Zn2+ and from yeast grown in the presence of 1.8 muM-MnSO4. The enzyme from yeast grown with added Zn2+ has the same properties as the crystalline enzyme from commercial supplies of baker's yeast. The enzyme from yeast grown without added An2+ has quite different properties. It has a mol.wt. in the region of 72000 and an S 20 w of 5.8S. The values can be compared with a mol.wt. of 141000 and an S 20 w of 7.6S for the crystalline enzyme. ADP-ribose, a common impurity in commercial samples of NAD+, is a potent competitive inhibitor of the new enzyme (K1 = 0.5 muM), but is not so for the crystalline enzyme. The observed maximum rate of ethanol oxidation at pH 7.05 and 25 degrees C was decreased 12-fold by the presence of 0.06 mol of inhibitor/mol of NAD+ when using the enzyme from Zn2+-deficient yeast, but with crystalline enzyme the maximum rate was essentially unchanged by this concentration of inhibitor. The kinetic characteristics for the two enzymes with ethanol, butan-1-ol, acetaldehyde and butyraldehyde as substrates are markedly different. These kinetic differences are discussed in relation to the mechanism of catalysis for the enzyme from Zn2+-deficient yeast.
乙醇脱氢酶是从在20 μM - MnSO₄存在且未添加Zn²⁺的条件下生长的酵母（酿酒酵母）以及在1.8 μM - MnSO₄存在的条件下生长的酵母中部分纯化得到的。从添加了Zn²⁺的酵母中提取的这种酶与市售面包酵母的结晶酶具有相同的性质。从未添加Zn²⁺的酵母中提取的酶则具有 quite different properties（原文此处有误，应为quite different properties，意为“截然不同的性质”）。它的分子量在72000左右，沉降系数S₂₀w为5.8S。这些数值可与结晶酶的分子量141000和沉降系数S₂₀w为7.6S相比较。ADP - 核糖是NAD⁺商业样品中的常见杂质，它是新酶的强效竞争性抑制剂（K₁ = 0.5 μM），但对结晶酶并非如此。当使用来自缺锌酵母的酶时，在pH 7.05和25℃条件下观察到的乙醇氧化最大速率在存在0.06摩尔抑制剂/摩尔NAD⁺时降低了12倍，但对于结晶酶，该浓度的抑制剂基本未改变最大速率。以乙醇、丁醇 - 1、乙醛和丁醛为底物时，这两种酶的动力学特征明显不同。针对缺锌酵母中该酶的催化机制讨论了这些动力学差异。
