Davies D D, Patil K D
Biochem J. 1974 Jan;137(1):45-53. doi: 10.1042/bj1370045.
A purification of ;malic' enzyme from potato is described. The purified enzyme is specific for NADP and requires a bivalent cation for activity. At pH values below 7 the plot of rate versus malate concentration approximates to normal Michaelis-Menten kinetics. At pH values above 7 the plot of rate versus malate concentration is sigmoid. A number of dicarboxylic acids activate the enzyme and remove the sigmoidicity. The enzyme is inhibited by phosphate, triose phosphates and AMP. In general, effectors of the oxidative decarboxylation of malate behave in the same manner in the reductive carboxylation of pyruvate. The response of the enzyme to energy charge is reported and the physiological significance of the response to metabolites is discussed in relation to the proposed role of the enzyme in the control of pH.
本文描述了从马铃薯中纯化“苹果酸”酶的方法。纯化后的酶对NADP具有特异性,且活性需要二价阳离子。在pH值低于7时,反应速率与苹果酸浓度的关系曲线近似于正常的米氏动力学。在pH值高于7时,反应速率与苹果酸浓度的关系曲线呈S形。多种二羧酸可激活该酶并消除S形曲线。该酶受到磷酸盐、磷酸丙糖和AMP的抑制。一般来说,苹果酸氧化脱羧的效应物在丙酮酸还原羧化中表现出相同的行为。报告了该酶对能荷的响应,并结合该酶在pH调节中所提出的作用,讨论了对代谢物响应的生理意义。