Mn(II) Binding and Subsequent Oxidation by the Multicopper Oxidase MnxG Investigated by Electron Paramagnetic Resonance Spectroscopy.
Mn(II) Binding and Subsequent Oxidation by the Multicopper Oxidase MnxG Investigated by Electron Paramagnetic Resonance Spectroscopy.
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DOI：
10.1021/jacs.5b04331
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发表时间：
2015-08
影响因子：
15
通讯作者：
Lizhi Tao;T. A. Stich;Cristina N Butterfield;Christine A. Romano;T. Spiro;B. Tebo;W. Casey;R. Britt
中科院分区：
文献类型：
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作者：
Lizhi Tao;T. A. Stich;Cristina N Butterfield;Christine A. Romano;T. Spiro;B. Tebo;W. Casey;R. Britt
通过电子顺磁共振（EPR）光谱检查了含有多功能的氧化酶（MCO）的锰固体形成（AS MNOX）的动力学。然后与Mn（II）反应在7到600 s之间，表明底物锰的快速氧化（使用使用速率系数建模的两相伪一阶动力学： k（1OB）= 0.205±0.001 s（-1）和k（2obs）= 0.019±0.001 s（-1））。 Mn（ii）。 （ii）离子通过一个氮配体协调MNX复合物，（iii）弱交换耦合二聚体Mn（II）物种为这些发现提供了对锰矿化分子机制的新见解。
The dynamics of manganese solid formation (as MnOx) by the multicopper oxidase (MCO)-containing Mnx protein complex were examined by electron paramagnetic resonance (EPR) spectroscopy. Continuous-wave (CW) EPR spectra of samples of Mnx, prepared in atmosphere and then reacted with Mn(II) for times ranging from 7 to 600 s, indicate rapid oxidation of the substrate manganese (with two-phase pseudo-first-order kinetics modeled using rate coefficients of: k(1obs) = 0.205 ± 0.001 s(-1) and k(2obs) = 0.019 ± 0.001 s(-1)). This process occurs on approximately the same time scale as in vitro solid MnOx formation when there is a large excess of Mn(II). We also found CW and pulse EPR spectroscopic evidence for at least three classes of Mn(II)-containing species in the reaction mixtures: (i) aqueous Mn(II), (ii) a specifically bound mononuclear Mn(II) ion coordinated to the Mnx complex by one nitrogenous ligand, and (iii) a weakly exchange-coupled dimeric Mn(II) species. These findings provide new insights into the molecular mechanism of manganese mineralization.