pH-Dependent reactivity for glycyl-L-tyrosine in carboxypeptidase-A-catalyzed hydrolysis.
pH-Dependent reactivity for glycyl-L-tyrosine in carboxypeptidase-A-catalyzed hydrolysis.
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DOI：
10.1021/jp2046504
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发表时间：
2011-09-01
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;Cao, Ruyin;Xu, Dingguo;Guo, Hua
二肽甘氨酰-L-酪氨酸（戈伊）可以是羧肽酶A（CPA）的底物或抑制剂，这取决于pH值。在这项工作中，我们研究了pH值依赖的反应性，这种二肽在CPA催化水解使用相结合的量子力学和分子力学方法。结果表明，单离子形式的二肽，普遍在高pH值，螯合活性位点的锌离子，使酶失活。这种抑制形式与CPA-GY复合物的早期X射线结构一致。另一方面，发现二肽在低pH下的普遍的二离子形式通过亲核机制进行水解，导致酰基-酶复合物。该反应中间体的稳定性与先前的低温固态NMR结果一致。计算的总自由能垒为20.1千卡/摩尔，与实验值19.9千卡/摩尔非常一致。
The dipeptide glycyl-L-tyrosine (GY) can be either a substrate for carboxypeptidase A (CPA) or an inhibitor, depending on pH. In this work, we investigate the pH dependent reactivity of this dipeptide in CPA catalyzed hydrolysis using a combined quantum mechanical and molecular mechanical method. It is shown that the mono-ionic form of the dipeptide, prevalent at high pH, chelates the active-site zinc ion, rendering the enzyme inactive. This inhibitory form is consistent with an earlier X-ray structure of the CPA-GY complex. On the other hand, the prevailing di-ionic form of the dipeptide at low pH was found to undergo hydrolysis via nucleophilic mechanism, leading to an acyl-enzyme complex. The stability of this reaction intermediate is consistent with previous low-temperature solid-state NMR results. The calculated overall free energy barrier of 20.1 kcal/mol is in excellent agreement with the experimental value of 19.9 kcal/mol.
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影响因子：
15
作者：
CHRISTIANSON, DW;LIPSCOMB, WN
通讯作者：
LIPSCOMB, WN
影响因子：
2.9
作者：
KIM, H;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：
4.4
作者：
JORGENSEN, WL;CHANDRASEKHAR, J;KLEIN, ML
通讯作者：
KLEIN, ML
DOI：
10.1073/pnas.82.20.6840
发表时间：
1985-01-01
影响因子：
11.1
作者：
CHRISTIANSON, DW;LIPSCOMB, WN
通讯作者：
LIPSCOMB, WN