双功能阿比二烯合成酶:在两个不同的活性位点之间, (+) - 基二酸盐中间体的自由扩散转移
R J Peters1, M M Ravn, R M Coates
1Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, USA.
Journal of the American Chemical Society
|September 13, 2001
概括
阿比他合成酶 (AS) 使用两个不同的活性位点将格拉尼尔格拉尼尔二酸盐转化为二烯. 这些位点位于单独的领域,为中间体二酸的自由扩散机制提供便利.
科学领域:
- 生物化学 生物化学
- 酶学 是一种酶学.
- 植物科学 植物科学
背景情况:
- 阿比他合成酶 (AS) 在大树 (Abies grandis) 中启动树脂酸生物合成.
- AS催化了两种不同的循环反应,从格兰二酸盐 (GGPP) 开始.
- 第一个反应产生 (+) - 二酸 (CPP),这是一个稳定的双循环中间体.
研究的目的:
- 为了研究Abietadiene Synthase (AS) 的催化机制和活性位点组织.
- 为了确定AS是否具有其顺序循环反应的独特活性位点.
- 阐明活跃地点之间的中间转移机制.
主要方法:
- 使用过渡状态模拟抑制剂 (14,15-二-15-azageranylgeranyl二酸盐).
- 产生的位点定向突变,准保存的富含亚斯巴酸盐的动机.
- 进行了酶动力学和补充研究.
主要成果:
- 证明AS使用两个不同的活跃站点进行连续循环.
- 特定基因的突变取消了一种催化活动,暗示了单独的领域.
- 突变的补充和自由CPP的检测证实了自由扩散转移机制.
- 突变酶增强了野生类型的AS活性,表明复杂的动力相互作用.
结论:
- 附加系统通过两个空间分离的活跃站点在不同的域内运行.
- 中间体 (+) - 二酸在这些活性位点之间自由扩散.
- 这种机制提供了关于二二烯生物合成的动力复杂性的见解.
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