一种可电离的活性位点托赋予过氧化酶核心的催化酶活性
Peter C Loewen1, Xavi Carpena, Pietro Vidossich
1Department of Microbiology, University of Manitoba , Winnipeg MB R3T 2N2, Canada.
Journal of the American Chemical Society
|May 3, 2014
概括
催化酶过氧化酶 (KatG) 通过活性位点的Trp脱质,模仿单功能催化酶,通过不成比例的过氧化. 一个移动的阿基尼因作为电子开关,控制这一关键的催化步骤.
科学领域:
- 生物化学 生物化学
- 结构生物学 结构生物学
- 酶学 是一种酶学.
背景情况:
- catalase过氧化酶 (KatG) 是一种双功能的血红蛋白.
- KatG的催化活性显示,不成比例的过氧化.
- 与单功能催化酶相比,它们具有结构上的差异.
研究的目的:
- 阐明KatG中催化反应的机制.
- 了解活动现场残留物在KatG功能中的作用.
- 为了比较KatG的机制与单功能催化酶的机制.
主要方法:
- 使用X射线结晶学来确定KatG的结构.
- 进行了量子力学/分子力学 (QM/MM) 计算.
- 整合了结构和计算数据来分析反应机制.
主要成果:
- 催化反应机制涉及到活性位点托 (Trp) 的去质子化.
- 这种活性位点的Trp功能类似于单功能催化酶中远端的histidine (his).
- 一个移动的氨酸残留物与一个Met-Tyr-Trp adduct相互作用,作为一个电子开关.
结论:
- 这项研究揭示了KatG的新型催化机制,涉及Trp去质子化.
- 移动阿基尼因在激活催化部位方面发挥着关键的调节作用.
- KatG的独特结构通过与单功能催化酶不同的机制实现了催化活性.
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