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Refining details of the structural and electronic properties of the CuB site in pMMO enzyme through sequential molecular dynamics/CPKS-EPR calculations
Physical Chemistry Chemical Physics ( IF 2.9 ) Pub Date : 2022-06-16 , DOI: 10.1039/d2cp01217k
William Daniel B Da Silva 1 , Roberta P Dias 2 , Júlio C S Da Silva 1
Affiliation  

This work investigated the structural and electronic properties of the copper mononuclear site of the PmoB part of the pMMO enzyme at the molecular level. We propose that the CuB catalytic site in the soluble portion of pMMO at room temperature and under physiological conditions is a mononuclear copper complex in a distorted octahedral arrangement with the residues His33, His137, and His139 on the equatorial base and two water molecules on the axial axis. Our view was based on the molecular dynamics results and DFT calculations of the electronic paramagnetic resonance parameters and comparisons with experimental EPR data. This new proposed model for the CuB site brings additional support concerning the recent experimental evidence, which pointed out that a saturated coordination sphere of the copper ion in the CuB center is an essential factor that makes it less efficient than the CuC site in the methane oxidation. Therefore, according to the CuB site model proposed here, an additional step involving a displacement of at least one water molecule of the copper coordination sphere by the O2 molecule prior to its activation must be necessary. This scenario is less likely to occur in the CuC center once this one is buried in the alpha-helices, which are part of the pMMO structure bound to the membrane wall, and consequently located in a less solvent-exposed region. In addition, we also present a simple and efficient sequential S-MD/CPKS protocol to compute EPR parameters that can, in principle, be expanded for the study of other copper-containing proteins.

中文翻译:

通过顺序分子动力学/CPKS-EPR 计算细化 pMMO 酶中 CuB 位点的结构和电子特性细节

这项工作在分子水平上研究了 pMMO 酶的 PmoB 部分的铜单核位点的结构和电子特性。我们提出,在室温和生理条件下,pMMO 可溶部分中的 Cu B催化位点是一种单核铜络合物,呈扭曲的八面体排列,赤道底上的残基 His 33、His 137和 His 139和两个水轴上的分子。我们的观点是基于电子顺磁共振参数的分子动力学结果和DFT计算以及与实验EPR数据的比较。这个新提出的 Cu B模型位点为最近的实验证据提供了额外的支持,该证据指出,Cu B中心的铜离子的饱和配位球是使其在甲烷氧化中的效率低于 Cu C位点的重要因素。因此,根据此处提出的Cu B位点模型,必须有一个额外的步骤,该步骤涉及在O 2分子激活之前将铜配位球的至少一个水分子置换。这种情况不太可能发生在 Cu C一旦这个被埋在α螺旋中,它是与膜壁结合的pMMO结构的一部分,因此位于溶剂暴露较少的区域。此外,我们还提出了一种简单有效的顺序 S-MD/CPKS 协议来计算 EPR 参数,原则上,该协议可以扩展用于其他含铜蛋白质的研究。
更新日期:2022-06-16
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