在稳定状态和前稳定状态条件下, (E) -4-基-3-甲基-2-乙烯二酸盐合成酶 (GcpE/IspG) 的偏磁中间体
Weiya Xu1, Nicholas S Lees, Dolapo Adedeji
1Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, USA.
Journal of the American Chemical Society
|September 25, 2010
概括
GcpE/IspG酶使用其铁硫集群在异烯生物合成中将MEcPP转化为HMBPP. EPR/ENDOR研究显示基质与集群结合,这意味着它涉及基组去除.
科学领域:
- 生物化学 生物化学
- 酶学 是一种酶学.
- 异烯生物合成 异烯生物合成
背景情况:
- 甲基酸 (MEP) 途径对于异烯生物合成至关重要.
- GcpE/IspG催化了最后一步之前的过程,将MEcPP转换为HMBPP.
- 这种反应涉及环开放和基组去除,需要两个电子.
研究的目的:
- 为了阐明 (E) -4-基-3-甲基-2-乙烯基二酸盐合成酶 (GcpE/IspG) 的机制.
- 调查活性位点 [4Fe-4S] 集群在酶反应中的作用.
- 描述催化过程中的过渡性和累积性磁性物种.
主要方法:
- 平稳状态和前平稳状态的动力学研究.
- 电子磁共振 (EPR) 光谱检测磁共振物种.电子磁共振 (EPR) 光谱检测磁共振物种.
- 用 (57) Fe进行同位素标记,以确认铁硫团的参与.
- (31) P-ENDOR光谱检测基质/产品结合的近距离.
主要成果:
- 观察到过渡性 (FeS(A)) 和累积性 (FeS(B)) 偏磁物种,这两种都是以铁硫为基础的.
- FeS(A) 显示弱 (31) P 合,这表明基质在集群附近结合.
- FeS(B) 也显示了 (31) P 合,这归因于产品 (HMBPP) 的结合.
结论:
- 建议在反应过程中直接与 [4Fe-4S] 集群结合基质.
- 结论是,铁硫集群直接参与氧基的减少性消除.
- 证明了与基质和产品的明显集群相互作用.
相关概念视频
IP3/DAG Signaling Pathway
Membrane lipids such as phosphatidylinositol (PI) are precursors for several membrane-bound and soluble second messengers. Specific kinases phosphorylate PI and produce phosphorylated inositol phospholipids. One such inositol phospholipids are the phosphatidylinositol-4,5 bisphosphate [PI(4,5)P2], present in the inner half of the lipid bilayer. Upon ligand binding, GPCR stimulates Gq proteins to turn on phospholipase Cꞵ. Activated phospholipase Cꞵ cleaves PI(4,5)P2 and produces two-second...
Energy Diagrams, Transition States, and Intermediates
Free-energy diagrams, or reaction coordinate diagrams, are graphs showing the energy changes that occur during a chemical reaction. The reaction coordinate represented on the horizontal axis shows how far the reaction has progressed structurally. Positions along the x-axis close to the reactants have structures resembling the reactants, while positions close to the products resemble the products. Peaks on the energy diagram represent stable structures with measurable lifetimes, while other...


