激进S-Adenosyl-l-methionine反应的范式转变:有机金属中间体 Ω 是催化剂的核心
Amanda S Byer1, Hao Yang2, Elizabeth C McDaniel1
1Department of Chemistry & Biochemistry , Montana State University , Bozeman , Montana 59717 , United States.
Journal of the American Chemical Society
|June 30, 2018
概括
激进的S-adenosyl-l-methionine (SAM) 酶利用一种新的有机金属中间体, Ω,对于超级家族的催化是必不可少的. 这一发现扩大了我们对激进SAM酶生物有机金属化学的理解.
科学领域:
- 生物化学
- 酵素学
- 生物有机金属化学
背景情况:
- 激进的S-adenosyl-l-methionine (SAM) 酶对于各种生物反应至关重要.
- 这些酶通过SAM的同溶性裂变产生反应性5'-脱氧氨基基基 (5'-dAdo·).
- 在酸甲酸酶激活酶 (PFL-AE) 中观察到一种以前未被描述的有机金属中间体 Ω.
研究的目的:
- 研究 Ω 中间体在激素 SAM 酶超级家族中的广泛相关性.
- 确定 Ω 在 PFL-AE 催化机制中的作用.
- 阐明 Ω 介质的结构性质及其对基质化学的影响.
主要方法:
- 用不同的基质混合顺序进行酶动力学研究.
- 频谱分析包括电子磁共振 (EPR) 和电子核双共振 (ENDOR).
- 在多样化的SAM激素酶组中进行比较分析,代表各种反应类型.
主要成果:
- Ω中间体具有催化能力,无论混合顺序如何,在PFL-AE中始终形成.
- 在跨越不同反应类的多个激素SAM酶中证实了 Ω 形成.
- 光谱数据显示了 Ω 内部的 Fe-C5' 键,将 5'-dAdo· 与 [4Fe-4S] 集群连接起来,类似于同酶 B12.
结论:
- Ω中间体是整个SAM酶超级家族中保存和必不可少的特征.
- 在 Ω 中的 Fe-C5' 键代表了一种用于启动激进反应的新生物有机金属动机.
- 这一发现显著扩大了自然界生物金属化学的已知范围,特别是在广大的SAM酶超级家族中.
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