Misset O, Brouwer M, Robillard G T
Biochemistry. 1980 Mar 4;19(5):883-90. doi: 10.1021/bi00546a009.
In vitro kinetic measurements have been performed by using purified HPr, EI, and a membrane fraction of EII from the Escherichia coli phosphoenolypyruvate-dependent sugar transport system. These measurements reveal very large lag times in the formation of methyl alpha-glucoside phosphate which are a function of the EI and the EII concentrations. The lag times decrease with increasing concentrations of EI but they increase with increasing concentrations of EII. When EI, together with Mg2+ and phosphoenolpyruvate, is preincubated at 37 degrees C before starting the kinetic measurements, the lag time can be decreased or eliminated. We have shown that the process responsible for the lag time is the activation of EI by dimerization which is influenced by Mg2+ and phosphoenolpyruvate.
通过使用纯化的HPr、EI以及来自大肠杆菌磷酸烯醇丙酮酸依赖性糖转运系统的EII膜组分进行了体外动力学测量。这些测量揭示了在α-葡萄糖苷磷酸形成过程中存在非常长的滞后时间，该滞后时间是EI和EII浓度的函数。滞后时间随EI浓度的增加而减少，但随EII浓度的增加而增加。当在开始动力学测量之前将EI与Mg2+和磷酸烯醇丙酮酸在37℃下预孵育时，滞后时间可以减少或消除。我们已经表明，导致滞后时间的过程是EI通过二聚化的激活，这受到Mg2+和磷酸烯醇丙酮酸的影响。
