人红细胞己糖激酶的动力学。温度、ATP4-和镁离子的影响。

Kinetics of human erythrocyte hexokinase. Influence of temperature, ATP4- and magnesium ions.

作者信息

Rijksen G, Staal G E

出版信息

Biochim Biophys Acta. 1976 Dec 8;452(2):382-91. doi: 10.1016/0005-2744(76)90187-x.

Abstract

Human erythrocyte hexokinase (EC 2.7.1.1) is inhibited competitively with respect to Mg-ATP2- by uncomplexed Mg2+ (Ki = 16--18 mM) and ATP4- (Ki = 1.6 mM). No real activation by low concentrations of Mg2+ could be detected and no allosteric behaviour was observed under the conditions tested. The temperature dependence of the enzyme was studied in relationship to the presence of Mg2+ or ATP4-. At equal concentrations of Mg2+ and ATP4- a break in the Arrhenius plot was observed at 27.5 degrees C, the higher temperature form of the enzyme having the lower activation energy. This break point in the Arrhenius plot was shifted to 36 degrees C in the presence of 5 mM Mg2+. A straight-line relationship was observed in the presence of 2.5 mM ATP4-. The Km for Mg-ATP2- showed a linear increase at temperatures over about 36 degrees C independent of the presence of Mg2+ or ATP4-. The nature of these phenomena is discussed.

摘要

人红细胞己糖激酶（EC 2.7.1.1）被未络合的Mg²⁺（Ki = 16 - 18 mM）和ATP⁴⁻（Ki = 1.6 mM）对Mg - ATP²⁻产生竞争性抑制。未检测到低浓度Mg²⁺的真正激活作用，在所测试的条件下也未观察到别构行为。研究了该酶的温度依赖性与Mg²⁺或ATP⁴⁻存在的关系。在Mg²⁺和ATP⁴⁻浓度相等时，在27.5℃观察到阿累尼乌斯图中有一个断点，酶的较高温度形式具有较低的活化能。在存在5 mM Mg²⁺的情况下，阿累尼乌斯图中的这个断点移至36℃。在存在2.5 mM ATP⁴⁻时观察到直线关系。Mg - ATP²⁻的Km在温度超过约36℃时呈线性增加，与Mg²⁺或ATP⁴⁻的存在无关。讨论了这些现象的性质。