蛋白质结构对形成腔的突变的反应及其与疏水效应的关系
A E Eriksson1, W A Baase, X J Zhang
1Institute of Molecular Biology, Howard Hughes Medical Institute, Eugene, OR.
概括
通过突变疏水性残留物在T4溶酶中产生空洞,降低了蛋白质的稳定性. 这种不稳定与腔体大小相关,为蛋白质中疏水效应提供了洞察力.
科学领域:
- 蛋白质工程是一种蛋白质工程.
- 生物物理学的生物物理.
- 结构生物学是结构生物学.
背景情况:
- 疏水效应是蛋白质折叠的主要驱动力.
- 了解疏水相互作用的能量贡献对于蛋白质的稳定性至关重要.
- 之前的研究对水效应的强度产生了相互矛盾的结果.
研究的目的:
- 为了研究蛋白质的疏水核内部产生空洞的能量后果.
- 量化空腔体积和蛋白质不稳定之间的关系.
- 为了协调有关蛋白质中疏水效应的相互矛盾的数据.
主要方法:
- 在菌体T4溶酶中构建了六种"产生腔"的突变.
- 使用pH诱导的脱化来确定蛋白质稳定性.
- 高分辨率的X射线晶体学,以描述突变蛋白质的结构.
主要成果:
- 突变L46A,L99A,L118A,L121A,L133A和F153A使蛋白质稳定性降低了2.7-5.0千卡的mol-1.0千卡.
- 一种双重突变 (L99A/F153A) 显示稳定性降低了8.3kcal mol-1.
- 创建的空洞范围从24到150A3,没有观察到溶剂分子.
- 蛋白质不稳定与创建的空洞的大小成比例.
结论:
- 在疏水核中创建一个空洞的能量成本取决于它的体积.
- 蛋白质中的疏水效应可以用一个常数和一个与腔体大小成比例的项来描述.
- 这项研究为了解疏水效应和协调先前发现提供了一个框架.
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