Silber P, Chung H, Gargiulo P, Schulz H
J Bacteriol. 1974 Jun;118(3):919-27. doi: 10.1128/jb.118.3.919-927.1974.
A reduced nicotinamide adenine dinucleotide phosphate (NADPH)-dependent reductase with the ability to reduce diacetyl has been isolated from Escherichia coli and has been purified 800-fold to near homogeneity. The product of the reduction of diacetyl was shown to be acetoin. The enzyme proved to catalyze the oxidation of NADPH in the presence of both uncharged alpha- and beta-dicarbonyl compounds. Even monocarbonyl compounds showed slight activity with the enzyme. On the basis of its substrate specificity, it is suggested that the enzyme functions as a diacetyl reductase. In contrast to other diacetyl reductases, the one reported here is specific for NADPH and does not possess acetoin reductase activity. The pH optimum of this enzyme was found to be between 6 and 7. The maximal velocity for the NADPH-dependent reduction of diacetyl was determined to be 9.5 mumol per min per mg of protein and the K(m) values for diacetyl and NADPH were found to be 4.44 mM and 0.02 mM, respectively. The molecular weight was estimated by gel filtration on Sephadex G-100 to be approximately 10,000.
一种能够还原双乙酰的依赖于还原型烟酰胺腺嘌呤二核苷酸磷酸（NADPH）的还原酶已从大肠杆菌中分离出来，并已纯化了800倍，达到近乎同质的状态。双乙酰还原反应的产物被证明是乙偶姻。该酶被证明在不带电荷的α-和β-二羰基化合物存在的情况下催化NADPH的氧化。甚至单羰基化合物对该酶也表现出轻微的活性。基于其底物特异性，推测该酶作为双乙酰还原酶发挥作用。与其他双乙酰还原酶不同，此处报道的这种酶对NADPH具有特异性，并且不具有乙偶姻还原酶活性。发现该酶的最适pH值在6至7之间。NADPH依赖的双乙酰还原反应的最大速度被确定为每毫克蛋白质每分钟9.5微摩尔，双乙酰和NADPH的米氏常数（K(m)）分别被发现为4.44毫摩尔和0.02毫摩尔。通过在Sephadex G - 100上进行凝胶过滤估计其分子量约为10,000。
