Intrinsic Carbon-Carbon Bond Reactivity at the Manganese Center of Oxalate Decarboxylase from Density Functional Theory.
Intrinsic Carbon-Carbon Bond Reactivity at the Manganese Center of Oxalate Decarboxylase from Density Functional Theory.
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根据密度泛函理论，草酸脱羧酶锰中心的固有碳-碳键反应性。
DOI：
10.1021/ct050063d
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发表时间：
2005
影响因子：
5.5
通讯作者：
N. Richards
中科院分区：
文献类型：
--
作者：
Christopher H. Chang;N. Richards
草酸脱羧酶（OxDC）催化草酸非氧化脱羧反应的详细锰依赖性化学仍然知之甚少。例如，酶活性需要分子氧的存在，即使该化合物不是反应中的形式底物。我们现在报告的密度泛函理论（DFT）计算后，一系列假设的OxDC活性位点模型结构。我们的研究结果表明，金属离子的功能可能是定位分子氧和草酸盐，使电子可以直接穿梭在这些物种之间，从而消除了需要存在的Mn（III）作为中间体的机制。这些计算还表明，枯草芽孢杆菌草酸脱羧酶活性中心的固有气相反应性是氧化草酸。由于OxDC没有观察到这种反应性，我们的DFT结果表明，蛋白质环境调节固有的锰中心反应性，可能是通过影响催化过程中锰中心的电子分布。
The detailed manganese-dependent chemistry employed by oxalate decarboxylase (OxDC) to catalyze the nonoxidative decarboxylation of oxalic acid remains poorly understood. For example, enzyme activity requires the presence of dioxygen even though this compound is not a formal substrate in the reaction. We now report density functional theory (DFT) calculations upon a series of hypothetical OxDC active site model structures. Our results suggest that the function of the metal ion may be to position dioxygen and oxalate such that electrons can be shuttled directly between these species, thereby removing the need for the existence of Mn(III) as an intermediate in the mechanism. These calculations also indicate that the intrinsic, gas-phase reactivity of the Bacillus subtilis oxalate decarboxylase active center is to oxidize oxalate. Since this reactivity is not observed for OxDC, our DFT results suggest that protein environment modulates the intrinsic metallocenter reactivity, presumably by affecting the electronic distribution at the manganese center during catalysis.