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首页> 外文期刊>Journal of biological inorganic chemistry: JBIC: a publication of the Society of Biological Inorganic Chemistry >Metalloproteins: structure and function-Cu binding and oxidation kinetics characterization of the multi-subunit Mn(II, III) oxidizing multicopper oxidase, Mnx, from Bacillus sp. PL-12
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Metalloproteins: structure and function-Cu binding and oxidation kinetics characterization of the multi-subunit Mn(II, III) oxidizing multicopper oxidase, Mnx, from Bacillus sp. PL-12

机译：金属蛋白：Bacillus sp。的多亚基Mn（II，III）氧化多铜氧化酶Mnx的结构和功能-Cu结合和氧化动力学表征。 PL-12

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摘要

In addition to chemical and physical forces, many global geochemical cycles, such as the redox cycling of manganese, are driven by bacteria. Bacterial Mn(II) oxidation and subsequent Mn(IV) mineral formation is widespread and diverse. Direct enzymatic Mn oxidation presents novel Mn chemistry in that Mn is the substrate of the reaction instead of the catalytic cofactor. Until recently, however, there has been no protein available to investigate. The heterologously purified Mn oxidase (Mnx) from marine Bacillus sp. PL-12 is made up of the multicopper oxidase (MCO) MnxG, and two hypothetical proteins MnxE and MnxF. Mnx binds Cu and oxidizes both Mn(II) and Mn(III), generating Mn(IV) oxide minerals that resemble those found on the Bacillus spore surface. Here we describe the characterization of Cu binding and substrate flexibility and present direct spectroscopic and kinetic evidence to verify the presence of the canonical MCO Cu types. Additionally, we describe the kinetics of the oxidation by Mnx of Mn(II) and the more typical MCO substrates Fe(II), 2,20-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) and 2, 6-dimethoxyphenol (2,6-DMP). Interestingly, Mn oxidation is the only reaction to take on an allosteric sigmoidal trend in lieu of Michaelis–Menten. This distinct trend may point towards a unique mechanism for this enzyme to catalyze the two direct electron transfers of Mn(II, III) oxidation. Elucidating the course of Mn oxidation within Mnx will unlock an unexplored corner of Mn chemistry and could begin to explain how and perhaps why bacteria oxidize Mn.
机译：除了化学和物理作用力外，许多全球地球化学循环（例如锰的氧化还原循环）也是由细菌驱动的。细菌Mn（II）氧化和随后的Mn（IV）矿物形成广泛且多样。直接酶促Mn氧化显示了新颖的Mn化学，其中Mn是反应的底物而不是催化辅因子。然而，直到最近，还没有蛋白质可供研究。从海洋芽孢杆菌中得到的异源纯化的Mn氧化酶（Mnx）。 PL-12由多铜氧化酶（MCO）MnxG和两个假设的蛋白质MnxE和MnxF组成。 Mnx结合Cu并氧化Mn（II）和Mn（III），从而生成类似于在芽孢杆菌孢子表面上发现的Mn（IV）氧化物矿物质。在这里，我们描述了铜结合和底物柔韧性的表征，并提出了直接的光谱和动力学证据来验证规范MCO Cu类型的存在。此外，我们描述了Mn（II）和更典型的MCO底物Fe（II），2,20-叠氮基双（3-乙基苯并噻唑啉-6-磺酸）（ABTS）和2的Mnx氧化动力学。 6-二甲氧基苯酚（2,6-DMP）。有趣的是，锰的氧化是代替米高斯-门滕的唯一变构S形趋势。这种明显的趋势可能指向该酶催化Mn（II，III）氧化的两个直接电子转移的独特机制。阐明Mnx内Mn的氧化过程将解锁Mn化学的一个尚未探索的角落，并可以开始解释细菌如何以及为什么氧化Mn。

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