Grossebüter W, Hartl T, Görisch H, Stezowski J J
Biol Chem Hoppe Seyler. 1986 Jun;367(6):457-63. doi: 10.1515/bchm3.1986.367.1.457.
Malate dehydrogenase from the thermoacidophilic archaebacterium Thermoplasma acidophilum is purified 50-fold to electrophoretic homogeneity. The purified enzyme crystallizes readily. Native malate dehydrogenase shows a relative molecular mass of 144 000. It is a tetramer of identical subunits with a relative molecular mass of 36 600. Malate dehydrogenase from Thermoplasma uses both NADH and NADPH as coenzyme to reduce oxaloacetate. The enzyme shows A-side (pro-R) stereospecificity for both coenzymes. The pH optimum for the reduction of oxaloacetate in the presence of NADH is found to be at pH 8.1. At pH 7.4 the Km value for oxaloacetate is found to be 5.6 microM while for NADH a value of 11.7 microM is found. The homogeneous enzyme shows a turnover number of kcat = 108 s-1.
来自嗜热嗜酸古细菌嗜酸热原体的苹果酸脱氢酶被纯化了50倍，达到电泳纯。纯化后的酶很容易结晶。天然苹果酸脱氢酶的相对分子质量为144000。它是由相对分子质量为36600的相同亚基组成的四聚体。嗜酸热原体的苹果酸脱氢酶同时使用NADH和NADPH作为辅酶来还原草酰乙酸。该酶对两种辅酶均表现出A面（前-R）立体特异性。发现在存在NADH的情况下还原草酰乙酸的最适pH为8.1。在pH 7.4时，草酰乙酸的Km值为5.6微摩尔，而NADH的值为11.7微摩尔。该纯酶的催化常数kcat = 108 s-1。
