Lerud R F, Whiteley H R
J Bacteriol. 1971 May;106(2):571-7. doi: 10.1128/jb.106.2.571-577.1971.
Micrococcus aerogenes grown in media containing glutamate has high levels of glutamate dehydrogenase and alpha-ketoglutarate reductase. The latter enzyme catalyzes the reversible reduction of alpha-ketoglutarate to alpha-hydroxyglutarate in the presence of reduced nicotinamide adenine dinucleotide (NADH). The enzyme has a high specificity for both substrates in either direction and displays Michaelis-Menten kinetics at moderate substrate concentrations. K(m) values of 0.12 to 0.17 mm alpha-ketoglutarate and 0.3 mm NADH for the forward reaction were calculated from data obtained at low substrate concentrations. At high concentrations, this reaction was inhibited by both substrates. The reverse reaction, which proceeded at 0.1 to 0.2 times the rate of the forward reactions, was inhibited by one of the products, alpha-ketoglutarate. K(m) values for the substrates of this reaction were 10 mm for alpha-hydroxyglutarate and 1 mm for nicotinamide adenine dinucleotide. alpha-Ketoglutarate reductase has a molecular weight of 7.5 x 10(4) to 8.2 x 10(4) and is composed of identical polypeptide chains with a molecular weight of 3.6 x 10(4) to 3.8 x 10(4).
在含有谷氨酸的培养基中生长的产气微球菌具有高水平的谷氨酸脱氢酶和α-酮戊二酸还原酶。后一种酶在还原型烟酰胺腺嘌呤二核苷酸（NADH）存在的情况下催化α-酮戊二酸可逆地还原为α-羟基戊二酸。该酶对两种底物在任何一个方向上都具有高度特异性，并且在中等底物浓度下呈现米氏动力学。根据在低底物浓度下获得的数据计算出正向反应中α-酮戊二酸的K(m)值为0.12至0.17 mM，NADH的K(m)值为0.3 mM。在高浓度下，该反应受到两种底物的抑制。逆向反应的速率为正向反应速率的0.1至0.2倍，受到产物之一α-酮戊二酸的抑制。该反应底物的K(m)值对于α-羟基戊二酸为10 mM，对于烟酰胺腺嘌呤二核苷酸为1 mM。α-酮戊二酸还原酶的分子量为7.5×10⁴至8.2×10⁴，由分子量为3.6×10⁴至3.8×10⁴的相同多肽链组成。
