PYRUVATE-KINASE, A POSSIBLE REGULATORY ENZYME IN HIGHER-PLANTS
PYRUVATE-KINASE, A POSSIBLE REGULATORY ENZYME IN HIGHER-PLANTS
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DOI：
10.1104/pp.52.4.312
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发表时间：
1973-01-01
期刊：
影响因子：
7.4
通讯作者：
DENNIS, DT
中科院分区：
文献类型：
--
作者：
DUGGLEBY, RG;DENNIS, DT
检查了许多植物物种的丙酮酸激酶（丙酮酸-ATP磷酸转移酶，EC 2.7.1.40）和水解磷酸烯醇丙酮酸的磷酸酶活性的存在。在这些检查中，只有棉花 (Gossypiumsp. L.) 种子被发现充分不含磷酸酶，从而可以进行丙酮酸激酶的动力学研究。在棉花种子发芽期间，丙酮酸激酶活性在前 3 天上升，之后回落至原始水平。这种发育模式是脂肪储存种子中参与将脂肪转化为碳水化合物的酶的特征。磷酸酶在发芽过程中也迅速升高，这使得在丙酮酸激酶的研究中无法使用幼苗提取物。没有发现证据表明棉苗中存在超过一种丙酮酸激酶。在未发芽种子的粗提物中，该酶与磷酸烯醇丙酮酸、镁以及较小程度的 ADP 方面的正常动力学略有偏差。通过离子交换色谱法部分纯化酶后，酶显示出正常的动力学。在粗制和部分纯化的制剂中，该酶被 AMP 激活，并被 ATP 和柠檬酸盐抑制。表明棉籽丙酮酸激酶是一种调节酶。
A number of plant species were examined for the presence of pyruvate kinase (pyruvate-ATP phosphotransferase, EC 2.7.1.40), and of a phosphatase activity which hydrolyzes phosphoenolpyruvate. Of those examined, only cotton (Gossypiumsp. L.) seeds were found to be sufficiently free of the phosphatase to permit a kinetic study of pyruvate kinase.During germination of cotton seeds, pyruvate kinase activity rises for the first 3 days, after which it falls back to its original level. This developmental pattern is characteristic of enzymes involved in the conversion of fat into carbohydrate in fatstoring seeds. The phosphatase also rose rapidly during germination, which precluded the use of extracts from seedlings in the study of pyruvate kinase. No evidence was found for the presence of more than one pyruvate kinase in cotton seedlings.In crude extracts from ungerminated seeds, the enzyme shows slight deviations from normal kinetics with respect to phosphoenolpyruvate, magnesium, and to a lesser extent, ADP. After partial purification of the enzyme by ion exchange chromatography, the enzyme shows normal kinetics. The enzyme is activated by AMP, and inhibited by both ATP and citrate, in both crude and partially purified preparations. It is suggested that cotton seed pyruvate kinase is a regulatory enzyme.