Storey B T, Kayne F J
Department of Obstetrics and Gynecology, University of Pennsylvania School of Medicine, Philadelphia 19174.
Fertil Steril. 1975 Dec;26(12):1257-65.
Seven enzymes of the Embden-Myerhof pathway of glycolysis were assayed in hypotonically treated epididymal sperm from mature rabbits. These were: fructose-biphosphate aldolase, triosephosphate isomerase, glyceraldehydephosphate dehydrogenase, 3-phosphoglyceromutase, enolase, pyruvate kinase, and lactate dehydrogenase. These enzymes were firmly enough bound to the cell structure to resist removal by washing after hypotonic treatment and had maximal activities comparable to, or greater than, the rate of mitochondrial pyruvate oxidation, so that rapid oxygen uptake was observed with intermediates of the glycolytic pathway. The activity of lactate dehydrogenase in a typical preparation of hypotonically treated cells was 5.3 mumoles/minute x 10(9) cells at 25 degrees C for pyruvate reduction in the hypotonically treated cells and 4.8 mumoles/minute x 10(9) cells in the thrice-washed hypotonically treated cells. The Km for pyruvate was 1.4 mM while that for lactate was 4.4 mM. By contrast, the maximal activity of pyruvate oxidation by mitochondria was 0.10 microgram atom of oxygen/minute x 10(9) cells, corresponding to 0.020 mumole of pyruvate/minute x 10(9) cells, and the Km for pyruvate was 5 microM. These enzyme parameters favor high lactate production from glucose in aerobic glycolysis.
对来自成年兔的经低渗处理的附睾精子中的糖酵解Embden-Myerhof途径的七种酶进行了测定。这些酶分别是：果糖二磷酸醛缩酶、磷酸丙糖异构酶、甘油醛-3-磷酸脱氢酶、3-磷酸甘油酸变位酶、烯醇化酶、丙酮酸激酶和乳酸脱氢酶。这些酶与细胞结构结合牢固，在低渗处理后经洗涤仍能保留，其最大活性与线粒体丙酮酸氧化速率相当或更高，因此在糖酵解途径的中间产物存在时可观察到快速的氧气摄取。在典型的经低渗处理的细胞制剂中，乳酸脱氢酶在25℃下将丙酮酸还原的活性为5.3微摩尔/分钟×10⁹个细胞，在经三次洗涤的低渗处理细胞中为4.8微摩尔/分钟×10⁹个细胞。丙酮酸的Km值为1.4 mM，而乳酸的Km值为4.4 mM。相比之下，线粒体丙酮酸氧化的最大活性为0.10微克原子氧/分钟×10⁹个细胞，相当于0.020微摩尔丙酮酸/分钟×10⁹个细胞，丙酮酸的Km值为5 microM。这些酶参数有利于在有氧糖酵解过程中从葡萄糖大量产生乳酸。
