Seok Y J, Zhu P P, Koo B M, Peterkofsky A
Department of Microbiology, College of Natural Sciences, Seoul National University, Korea.
Biochem Biophys Res Commun. 1998 Sep 18;250(2):381-4. doi: 10.1006/bbrc.1998.9323.
Enzyme I of the Escherichia coli phosphoenolpyruvate:sugar phosphotransferase system undergoes a slow monomer-dimer transition. In vitro autophosphorylation of Enzyme I by PEP was studied at limiting concentrations of the protein. Addition to incubation mixtures containing wild-type Enzyme I of inactive or low-activity mutant forms of Enzyme I resulted in stimulation of autophosphorylation activity. The kinetics of the activation fit well to a model in which the active form of Enzyme I is the dimer. These experiments provide support for the argument that only the dimeric form of Enzyme I can be autophosphorylated.
糖磷酸转移酶系统的酶I会发生缓慢的单体-二聚体转变。在蛋白质浓度有限的情况下，研究了酶I被磷酸烯醇丙酮酸（PEP）进行的体外自磷酸化。向含有野生型酶I的孵育混合物中添加无活性或低活性的酶I突变形式，会刺激自磷酸化活性。激活动力学很好地符合一个模型，即酶I的活性形式是二聚体。这些实验为只有酶I的二聚体形式才能被自磷酸化这一观点提供了支持。
