Guo Zhi, Xu Li-Na, Zhou Lin-Xiang
Surface Physics National Key Laboratory, Department of Physics, Fudan University, Shanghai 200433, China.
J Biomol Struct Dyn. 2006 Jun;23(6):603-12. doi: 10.1080/07391102.2006.10507085.
The quasielastic neutron scattering index beta and the modulus of a protein's quasi-electric dipole moment were utilized to quantitate the thermostability of wildtype TC23O and its mutants. Charged residues Arg314, Glu246, Glu291, and some prolines near the C-terminus of the sequence (Pro228, Pro296, and Pro308) were identified to be critical for the thermostability of wildtype TC23O according to these two criteria. By analyzing the molecular conformation changes during the simulation, it was demonstrated how the mutant P228S was destabilized by disrupting two salt-bridges Asp116OD1-Lys215N and Glu210OE1-Lys217N at an adjacent beta-turn. The destabilization of P296S also shown to be intimate correlated with the break down of ion pair Lys188N-Glu291OE1. The sensitivity of its electrostatic network to the local structure is an important feature. It reveals that the 'proline effect' and electrostatic interactions together influences the thermostability of TC23O a lot.
利用准弹性中子散射指数β和蛋白质准电偶极矩的模量来定量野生型TC23O及其突变体的热稳定性。根据这两个标准，序列C末端附近的带电残基Arg314、Glu246、Glu291以及一些脯氨酸（Pro228、Pro296和Pro308）被确定对野生型TC23O的热稳定性至关重要。通过分析模拟过程中的分子构象变化，证明了突变体P228S如何因破坏相邻β-转角处的两个盐桥Asp116OD1-Lys215N和Glu210OE1-Lys217N而变得不稳定。P296S的不稳定也显示与离子对Lys188N-Glu291OE1的断裂密切相关。其静电网络对局部结构的敏感性是一个重要特征。这表明“脯氨酸效应”和静电相互作用共同对TC23O的热稳定性有很大影响。
