法内赛二酸盐合成酶:基质选择性和立体选择性之间的妥协艺术
Hirekodathakallu V Thulasiram1, C Dale Poulter
1Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA.
Journal of the American Chemical Society
|December 7, 2006
概括
酸二合成酶在链延长过程中意外产生一些Z双键异构体,表明立体选择性和基质结合之间的平衡. 这发生在多种物种和体内.
科学领域:
- 酶学 是一种酶学.
- 生物化学 生物化学
- 有机化学 有机化学
背景情况:
- 法内西二酸盐 (FPP) 合成酶对于合成异oprenoids至关重要,催化异二酸盐 (IPP) 单元的头到尾凝结.
- 这种酶家族通常在添加C5异烯单元时安装E双键,导致 (E,E) -FPP.
- 这些反应的立体化学结果对下游代谢途径至关重要.
研究的目的:
- 为了研究FPP合成酶在链延长过程中的立体化学忠实性.
- 为了确定Z双键异构体是否在格兰二酸盐 (GPP) 和FPP的合成过程中形成.
- 阐明IPP凝结过程中双键形成和损失的机制.
主要方法:
- 来自各种来源 (鸟类,大肠杆菌,三角,P. furiosus,M. thermautotrophicus) 的净化FPP合成酶与基质的化.
- 使用染色学分析反应产物 (C10和C15) 来识别E-和Z-同位素.
- 使用同位素标记的基板,特别是 (R) - [2-2H]IPP和 (S) - [2-2H]IPP,以追踪的结合.
主要成果:
- 除了预期的E-异构体外,还检测到了少量的Z双键异构体,尼里二酸盐 (Z-C10) 和 (Z,E) -FPP.
- 这些Z-异构体在多种生物体和体内条件下形成.
- 来自 (S) - [2-2H]IPP的被纳入产品中,而来自 (R) - [2-2H]IPP的没有,表明IPP的C2处的亲R的损失.
结论:
- FPP合成酶可以产生Z双键异构体,这对于这个酶家族来说是意想不到的.
- Z-异构体的形成表明,在优化双键立体选择性和将DMAPP从IPP结合部位排除之间存在潜在的妥协.
- 来自IPP的pro-R的立体特异性损失在E和Z异构体合成中都保持不变.
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