Duff D A, Snell K
Biochem J. 1982 Jul 15;206(1):147-52. doi: 10.1042/bj2060147.
Phosphoenolpyruvate carboxykinase activity in crude extracts of muscle has frequently been determined by using a continuous spectrophotometric method, which is shown to grossly overestimate enzyme activity. NADH oxidation attributed to phosphoenolpyruvate carboxykinase activity in the assay is due to lactate production. Under the normal assay conditions. Na+ ions stimulate pyruvate kinase, providing pyruvate for lactate formation by lactate dehydrogenase and sufficiently to account for most of the observed NADH oxidation.
肌肉粗提物中磷酸烯醇式丙酮酸羧激酶的活性通常采用连续分光光度法测定,结果表明该方法会严重高估酶活性。测定中归因于磷酸烯醇式丙酮酸羧激酶活性的NADH氧化是由于乳酸生成。在正常测定条件下,钠离子刺激丙酮酸激酶,为乳酸脱氢酶生成乳酸提供丙酮酸,且足以解释大部分观察到的NADH氧化现象。