Kinetic study on the dimer-tetramer interconversion of glycogen phosphorylase a
Kinetic study on the dimer-tetramer interconversion of glycogen phosphorylase a
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DOI：
10.1046/j.1432-1327.1999.00058.x
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发表时间：
1999-02-01
期刊：
影响因子：
--
通讯作者：
Wang, ZX
中科院分区：
文献类型：
--
作者：
Wang, ZX
本文应用酶系统解离动力学理论研究了糖原磷酸化酶a的二聚体-四聚体相互转化。测定了磷酸化酶a解离-缔合反应的动力学常数。结果表明：（a）葡萄糖-1-磷酸的存在对磷酸化酶a的解离速率和缔合速率均无影响，因此不改变磷酸化酶a的二聚体-四聚体平衡：（B）糖原与磷酸化酶a的结合降低了二聚体形成四聚体的缔合速率，但对四聚体的解离速率无影响;（c）磷酸化酶A的二聚体和四聚体形式都可以结合糖原，但四聚体形式对糖原具有较低的亲和力，并且是无催化活性的。
Kinetic theory of dissociating enzyme systems has been applied to a study of the dimer-tetramer interconversion of glycogen phosphorylase a. All kinetic constants for the dissociating-associating reaction of phosphorylase a have been determined. The results indicate that (a) the presence of glucose-1-phosphate has no influence on either the rate of dissociation or the rate of association, and hence does not shift the dimer-tetramer equilibrium of phosphorylase a; (b) the binding of glycogen to the enzyme decreases the association rate of the dimer to form the tetramer, but has no effect on the dissociation rate of the tetramer; (c) both the dimeric and tetrameric form of phosphorylase a can bind glycogen, but the tetrameric form has a lower affinity for glycogen and is catalytically inactive.