Catalysis of carboxypeptidase A: promoted-water versus nucleophilic pathways.
Catalysis of carboxypeptidase A: promoted-water versus nucleophilic pathways.
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DOI：
10.1021/jp101448j
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发表时间：
2010-07-22
影响因子：
3.3
通讯作者：
Guo, Hua
中科院分区：
文献类型：
--
作者：
Wu, Shanshan;Zhang, Chunchun;Xu, Dingguo;Guo, Hua
用量子力学/分子力学（QM/MM）方法和高水平密度泛函理论研究了羧肽酶A（CPA）催化酯底物水解的机理.发现主要的机制是利用Glu 270辅助的活性位点水分子，并且这种所谓的促进水途径与CPA催化的蛋白水解反应中的途径相似（D. Xu和H. Guo，J. Am. 131，9780（2009））。另一方面，我们的模拟表明，存在一个替代途径，由于直接亲核攻击的Glu 270上易裂的羰基碳。这种所谓的亲核途径在蛋白水解反应中是不可行的，导致稳定的酰基-酶复合物。然而，亲核途径是非生产性的，因为它在脱酰步骤中被高屏障阻断。基于这里报道的结果，在我们以前的出版物，提出了一个统一的模型来解释几乎所有的实验观察有关CPA的催化。
The catalytic mechanism of carboxypeptidase A (CPA) for the hydrolysis of ester substrates is investigated using hybrid quantum mechanical/molecular mechanical (QM/MM) methods and high-level density functional theory. The prevailing mechanism was found to utilize an active-site water molecule assisted by Glu270 and this so-called promoted-water pathway is similar to that in the CPA catalyzed proteolytic reaction (D. Xu and H. Guo, J. Am. Chem. Soc. 131, 9780 (2009)). On the other hand, our simulations indicated the existence of an alternative pathway due to direct nucleophilic attack of Glu270 on the scissile carbonyl carbon. This so-called nucleophilic pathway, which is not viable in proteolytic reactions, leads to a stable acyl-enzyme complex. However, the nucleophilic pathway is non-productive as it is blocked by a high barrier in the deacylation step. Based on results reported here and in our earlier publication, a unified model is proposed to account for nearly all experimental observations concerning the catalysis of CPA.
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DOI：
10.1139/v94-264
发表时间：
1994-10-01
期刊：
CANADIAN JOURNAL OF CHEMISTRY-REVUE CANADIENNE DE CHIMIE
影响因子：
--
作者：
ALVAREZSANTOS, S;GONZALEZLAFONT, A;AVILES, FX
通讯作者：
AVILES, FX
影响因子：
15
作者：
CHRISTIANSON, DW;LIPSCOMB, WN
通讯作者：
LIPSCOMB, WN
影响因子：
3.5
作者：
Cho, JH;Kim, DH;Choi, KY
通讯作者：
Choi, KY
影响因子：
3
作者：
BROOKS, BR;BRUCCOLERI, RE;KARPLUS, M
通讯作者：
KARPLUS, M
影响因子：
4.4
作者：
BECKE, AD
通讯作者：
BECKE, AD