来自Methylococcus capsulatus (Bath) 的可溶性甲单氧基酶基酶的晶体结构在双核铁活性部位显示了几何变异性
1Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Journal of the American Chemical Society
|July 18, 2001
概括
溶性甲单氧基酶氧酶 (MMOH) 的结构研究揭示了其铁活性位点在不同氧化还原状态和pH水平上的动态变化. 这些发现为酶的催化机制提供了新的见解.
科学领域:
- 生物化学和结构生物学
- 酶学 是一种酶学.
- 金属蛋白化学 金属蛋白化学
背景情况:
- 可溶性甲单氧酶氧酶 (MMOH) 催化甲以甲醇氧化,使用碳酸盐桥架双核铁中心.
- 之前的研究强调了碳酸盐转移以及MMOH活性部位的键和pH的重要性.
- 了解MMOH活性部位的动态性质对于阐明其催化机制至关重要.
研究的目的:
- 调查MMOH活性部位的结构动力学在各种氧化还原状态 (二铁 (II),二铁 (III),混合价值Fe (II) 和Fe (III)) 和pH值 (6.2,7.0,8.5) 中.
- 为了确定影响催化作用的结合相互作用.
- 为观察到的光谱数据提供结构基础,并了解酶基质相互作用.
主要方法:
- 采用X射线晶体学来确定MMOH从Methylococcus capsulatus (Bath) 的结构.
- 获得了二铁 (II),二铁 (III) 和混合价值Fe (II) Fe (III) 氧化状态的结构.
- 在pH值6.2,7.0和8.5进行了实验,以评估pH值依赖的结构变化.
主要成果:
- 晶体结构为混合价值状态中的二铁中心提供了第一个视图,揭示了铁离子的可变性增加.
- 观察到Asn214的替代构造,与铁中心的氧化还原状态相关.
- 在二铁 (II) 状态下,与金属中心相邻的α螺旋体中发现了扭曲,影响了蛋白质表面的可访问性.
结论:
- 该研究描述了MMOH活性部位内的运动范围,并确定了关键的结相互作用.
- 观察到的结构变化,包括Asn214形状和螺旋扭曲,会影响活动地点的环境,并可能影响基板的访问.
- 这些发现与以前的光谱观测相协调,并为MMOH的催化机制提供了重要的新见解.
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