Botanisches Institut der Universität, Schloßgarten 3, D-4400, Münster, Federal Republic of Germany.
Planta. 1979 Oct;146(5):567-74. doi: 10.1007/BF00388833.
By ammonium sulfate fractionation and gel filtration an enzyme preparation which catalyzed NAD(+)-dependent L-lactate oxidation (10(-4) kat kg(-1) protein), as well as NADH-dependent pyruvate reduction (10(-3) kat kg(-1) protein), was obtained from leaves of Capsella bursa-pastoris. This lactate dehydrogenase activity was not due to an unspecific activity of either glycolate oxidase, glycolate dehydrogenase, hydroxypyruvate reductase, alcohol dehydrogenase, or a malate oxidizing enzyme. These enzymes could be separated from the protein displaying lactate dehydrogenase activity by gel filtration and electrophoresis and distinguished from it by their known properties. The enzyme under consideration does not oxidize D-lactate, and reduces pyruvate to L-lactate (the configuration of which was determined using highly specific animal L-lactate dehydrogenase). Based on these results the studied Capsella leaf enzyme is classified as L-lactate dehydrogenase (EC 1.1.1.27). It has a Km value of 0.25 mmol l(-1) (pH 7.0, 0.3 mmol l(-1) NADH) for pyruvate and of 13 mmol l(-1) (pH 7.8, 3 mmol l(-1) NAD(+)) for L-lactate. Lactate dehydrogenase activity was also detected in the leaves of several other plants.
通过硫酸铵分级沉淀和凝胶过滤，从荠菜叶片中获得了一种酶制剂，该酶制剂能催化 NAD(+)依赖的 L-乳酸氧化（10(-4) kat kg(-1) 蛋白）以及 NADH 依赖的丙酮酸还原（10(-3) kat kg(-1) 蛋白）。这种乳酸脱氢酶活性不是由于甘油酸氧化酶、甘油酸脱氢酶、羟丙酮酸还原酶、醇脱氢酶或苹果酸氧化酶的非特异性活性所致。这些酶可以通过凝胶过滤和电泳从显示乳酸脱氢酶活性的蛋白质中分离出来，并通过它们已知的性质将其与该酶区分开来。所研究的酶不氧化 D-乳酸，而是将丙酮酸还原为 L-乳酸（其构型使用高度特异性的动物 L-乳酸脱氢酶确定）。基于这些结果，研究中的荠菜叶酶被归类为 L-乳酸脱氢酶（EC 1.1.1.27）。它对丙酮酸的 Km 值为 0.25 mmol l(-1)（pH 7.0，0.3 mmol l(-1)NADH），对 L-乳酸的 Km 值为 13 mmol l(-1)（pH 7.8，3 mmol l(-1)NAD(+)）。在其他几种植物的叶片中也检测到了乳酸脱氢酶活性。
