Sequence-specific 1H NMR assignments and secondary structure of eglin c.
Sequence-specific 1H NMR assignments and secondary structure of eglin c.
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序列特异性 1H NMR 归属和eglin c 的二级结构。
DOI：
10.1021/bi00458a018
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发表时间：
1990
期刊：
影响因子：
2.9
通讯作者：
Wagner,G
中科院分区：
文献类型：
--
作者：
Hyberts,SG;Wagner,G
还发生了其他副反应，包括 EPSP 在活性位点水解产生丙酮酸以及中间体分解形成缩酮。这些反应也很慢；在没有磷酸盐的情况下，EPSP 的水解率为 4.7 X 10" 4 s" 1 (Anderson et al., 1988b)；在内平衡条件下，EPSP 占据 5% 的位点，我们预测丙酮酸形成速率为 2.4 X 10" 5 s" 1，这与观察到的速率一致。这些缓慢的副反应几乎没有增加新的机制信息来阐明活性位点的事件。例如，EPSP 的水解可能是活性位点底物质子化的函数，随后受到水而不是磷酸盐的攻击。 EPSP缩酮的形成可能会对与活性位点结合的中间体的几何形状产生影响，但反应的缓慢性和缩酮形成途径的不确定性可能会导致人们质疑这一结论的有效性。速率测量对于从结构数据中提取机械结论是必要的，当然，反之亦然。
Other side reactions were also shown to occur, involving the hydrolysis of EPSP at the active site to produce pyruvate and breakdown of the intermediate to form the ketal. These re-actions are also slow; the rate of EPSP hydrolysis in the ab-sence of phosphate is 4.7 X 10" 4 s" 1 (Anderson et al., 1988b); with 5% of the sites occupied by EPSP underinternal equi-librium conditions, we predict a rate of pyruvate formation of 2.4 X 10" 5 s" 1, which is consistent with the observed rate. These slow side reactions add little new mechanistic infor-mation to illuminate the events at the active site. For example, the hydrolysis of EPSP is probably a function of the protonation of the substrate at the active site followed by attack by water rather than phosphate. The formation of the EPSPketal might have implications for the geometry of the intermediate bound to the active site, but the slowness of the reaction and uncertainty of the pathway of formation of the ketal could lead one to question the validity of such conclusions. Rate mea-surements are necessary to extract mechanistic conclusions from structural data, and, certainly, the converse is equally true.