Functional role for Tyr 31 in the catalytic cycle of chicken dihydrofolate reductase
Functional role for Tyr 31 in the catalytic cycle of chicken dihydrofolate reductase
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Tyr 31 在鸡二氢叶酸还原酶催化循环中的功能作用
DOI：
--
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
R. Allemann
中科院分区：
文献类型：
--
作者：
P. Shrimpton;Alex Mullaney;R. Allemann
尽管做了大量的工作，二氢叶酸还原酶（DHFR）催化还原二氢叶酸的机制的许多关键方面仍然没有得到解决。在细菌形式的DHFR中，底物和水进入活性位点都受移动的M20环的构象控制。在脊椎动物DHFR中，仅观察到对应于M20环的残基的一种构象。进入活性位点的途径被提议由残基31控制。MD模拟鸡DHFR与底物和辅因子复合，揭示了在二氢叶酸结合的活性位点上关闭Tyr 31的侧链。这种构象变化取决于二氢叶酸的帕拉氨基苯甲酰胺部分上谷氨酸的存在。在没有它的情况下，构象保持开放。虽然水可以进入二氢叶酸的活性位点并与N5形成氢键，表明水作为质子供体的可行性，但这不受Tyr 31构象的控制。的活性位点的水的可及性是低的两种构象的酪氨酸31。然而，当氢化物从NADPH转移到质子化前的二氢叶酸的C6时，在此期间发现水在活性位点中的二氢叶酸的N5的氢键距离的平均时间增加了近5倍。这些结果表明，在DHFR催化还原过程中，水可以充当二氢叶酸的N5质子化的布朗斯台德酸。蛋白质2003;51：216-223.© 2003 Wiley利斯公司
Despite much work, many key aspects of the mechanism of the dihydrofolate reductase (DHFR) catalyzed reduction of dihydrofolate remain unresolved. In bacterial forms of DHFR both substrate and water access to the active site are controlled by the conformation of the mobile M20 loop. In vertebrate DHFRs only one conformation of the residues corresponding to the M20 loop has been observed. Access to the active site was proposed to be controlled by residue 31. MD simulations of chicken DHFR complexed with substrates and cofactor revealed a closing of the side chain of Tyr 31 over the active site on binding of dihydrofolate. This conformational change was dependent on the presence of glutamate on the para‐aminobenzoylamide moiety of dihydrofolate. In its absence, the conformation remained open. Although water could enter the active site and hydrogen bond to N5 of dihydrofolate, indicating the feasibility of water as the proton donor, this was not controlled by the conformation of Tyr 31. The water accessibility of the active site was low for both conformations of Tyr 31. However, when hydride was transferred from NADPH to C6 of dihydrofolate before protonation, the average time during which water was found in hydrogen bonding distance to N5 of dihydrofolate in the active site increased almost fivefold. These results indicated that water can serve as the Broensted acid for the protonation of N5 of dihydrofolate during the DHFR catalyzed reduction. Proteins 2003;51:216–223. © 2003 Wiley‐Liss, Inc.
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DOI：
10.2210/pdb3dfr/pdb
发表时间：
1982-11
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
J. Bolin;D. Filman;D. Matthews;R. Hamlin;J. Kraut
通讯作者：
J. Bolin;D. Filman;D. Matthews;R. Hamlin;J. Kraut
通过适用于重组人二氢叶酸还原酶的动力学方案预测了异常的瞬态和稳态动力学行为。
DOI：
--
发表时间：
1990
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Appleman,JR;Beard,WA;Delcamp,TJ;Prendergast,NJ;Freisheim,JH;Blakley,RL
通讯作者：
Blakley,RL
影响因子：
2.9
作者：
Sawaya, MR;Kraut, J
通讯作者：
Kraut, J
鸡肝二氢叶酸还原酶的晶体结构：二元硫代NADP和三元硫代NADP.生物蝶呤复合物。
影响因子：
2.9
作者：
McTigue,MA;Davies2nd,JF;Kaufman,BT;Kraut,J
通讯作者：
Kraut,J
影响因子：
2.9
作者：
DAVIES, JF;DELCAMP, TJ;KRAUT, J
通讯作者：
KRAUT, J