Brockman H L, Wood W A
J Bacteriol. 1975 Dec;124(3):1454-61. doi: 10.1128/jb.124.3.1454-1461.1975.
D-Lactate dehydrogenase has been purified to near homogeneity from Peptostreptococcus elsdenii. As isolated, the enzyme contains flavine adenine dinucleotide and a tightly bound metal cofactor. Inactivation by ortho-phenanthroline occurs in two steps and is partially blocked by D-lactate. Reactivation by divalent metal ions occurs, with divalent zinc being the most effective. When ferricyanide is used as the electron acceptor, D-lactate has an apparent K0.5 of 3.3 M0.46; its binding is negatively cooperative with a Hill coefficient of 0.46. Replacement of ferricyanide by the other components of the electron transport system yields hyperbolic kinetics with an apparent Km for D-lactate of 26 mM. The apparent Km for ferricyanide is 2.2 X 10(-4) M. Phosphate and pyrophosphate compounds stimulate the D-lactate:ferricyanide activity. These properties suggest that interaction of this enzyme with other electron transport proteins in the chain may enhance D-lactate binding and, hence, the rate of electron transport.
已从埃尔氏消化链球菌中纯化出近乎同质的D-乳酸脱氢酶。刚分离出来时，该酶含有黄素腺嘌呤二核苷酸和一个紧密结合的金属辅因子。邻菲罗啉使其失活分两步进行，且部分被D-乳酸阻断。二价金属离子可使其重新激活，其中二价锌最为有效。当铁氰化物用作电子受体时，D-乳酸的表观K0.5为3.3 M0.46；其结合具有负协同性，希尔系数为0.46。用电子传递系统的其他成分替代铁氰化物会产生双曲线动力学，D-乳酸的表观Km为26 mM。铁氰化物的表观Km为2.2×10(-4) M。磷酸盐和焦磷酸盐化合物会刺激D-乳酸：铁氰化物的活性。这些特性表明，该酶与链中其他电子传递蛋白的相互作用可能会增强D-乳酸的结合，从而提高电子传递速率。
