多铜氧化酶复合体Mnx的氧化:一个协调的两阶段Mn{II}/{III}和Mn{III}/{IV}机制
Alexandra V Soldatova1, Christine A Romano2, Lizhi Tao
1Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195, United States.
Journal of the American Chemical Society
|July 18, 2017
概括
细菌氧化酶MnxG通过两阶段的氧化将Mn(II) 转化为MnO2纳米粒子. 这项研究揭示了Mn(III) 不成比例,而不是直接的电子转移,驱动了第二个氧化阶段,澄清了氧化机制.
科学领域:
- 生物化学 生物化学
- 环境微生物学 环境微生物学
背景情况:
- 含有氧化酶MnxG的Mnx蛋白复合体是一种独特的多铜氧化酶 (MCO).
- 在两个不同的阶段,MnxG催化了Mn(II的两电子氧化到MnO2纳米粒子.
研究的目的:
- 阐明由MnxG催化的第二氧化阶段 (Mn(III) 到MnO2的机制.
- 调查酸盐 (PP) 作为Mn (III) 陷的作用及其对反应的影响.
主要方法:
- 电子偏磁共振 (EPR) 光谱检测到与酶结合的Mn (III).
- 动力测量以确定基质可访问性和反应途径.
- 使用酸盐 (PP) 作为Mn(III) 化剂和反应调节剂.
主要成果:
- EPR证实了与MnxG结合的Mn (III) 的存在.
- 动力数据显示Mn{\displaystyle Mn{\text{III}}) 被排除在Mn{\text{\text{II}}}的结合部位之外,排除了直接的酶电子转移.
- 建议在相邻的地点不成比例地氧化,从而促进间接氧化到Mn{IV}和Mn{II}回收.
- 发现酸盐可以化Mn{II}和Mn{III},减缓反应,并可能抑制催化.
结论:
- 通过MnxG将Mn (II) 转化为MnO2的第二氧化步骤涉及Mn (III) 不成比例,而不是直接将电子转移到酶.
- 酸盐起着复杂的作用,作为一个Mn (III) 陷,同时调节酶活性.
- 介绍了Mnx催化MnO2生产的综合机制,进步了对微生物氧化的理解.
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