由二次酶的子单元接口中的单个突变引起的合作性:氨酸减少酶
N S Scrutton1, M P Deonarain, A Berry
1Department of Biochemistry, University of Cambridge, United Kingdom.
概括
在大肠杆菌谷氨减少酶中发生的单一突变可以诱导酶功能的合作性. 通过突变破坏二聚体接口会产生分子开关,影响酶动力学和基质结合.
科学领域:
- 生物化学 生物化学
- 酶动力学 酶动力学
- 蛋白质结构 蛋白质结构
背景情况:
- 大肠杆菌氨酸减少酶是一种同位体酶,对细胞的氧化还原平衡至关重要.
- 了解控制酶合作的机制对于酶工程和药物开发至关重要.
研究的目的:
- 为了研究二聚体接口在调节大肠杆菌氨酸减少酶的全性行为中的作用.
- 为了确定二聚体接口的突变是否可以赋予酶的合作性.
主要方法:
- 局部导向的突变发生被用于用酸盐替代glycine418在E. coli谷氨减少酶中.
- 进行了酶动力学测试,以测量谷氨结合亲和力和合作力 (希尔系数).
- 通过混合野生类型和突变子单元进行异体化实验.
主要成果:
- 甘氨酸418转化为三的突变导致了一种高度合作的酶 (希尔系数1.76),用于结合谷氨.
- 在由一个突变体和一个野生类型子单元组成的异构体中,合作性被废除.
- 突变破坏了二聚体界面上的原子包装,改变了酶的动力机制.
结论:
- 远离活性部位的单个突变可以作为诱导酶合作性的分子开关.
- 双相接口在大肠杆菌谷氨减少酶的全调节中起着至关重要的作用.
- 蛋白质-蛋白质相互作用的破坏可以显著改变酶功能和动力学.
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