静电和疏水效应对TGEV主蛋白酶二聚体稳定性的影响

Efffects of Electrostatic and Hydrophobic Interaction on the Stability of the TGEV Main Proteinase Dimer

从TGEV 3CL蛋白酶二聚体结构出发,研究了TGEV 3CL蛋白酶二聚体单体之间的静电和疏水相互作用.蛋白质的静电相互作用通过有限差分方法求解Poisson-Boltzmann方程得到,疏水相互作用通过分析溶剂可及性表面模型得到.考察了不同pH值对TGEV 3CL蛋白酶二聚体静电和疏水相互作用的影响,在pH值为5.5-8.5时,二聚体静电相互作用能、静电去溶剂化能和疏水自由能都较小,表明在该条件下静电和疏水相互作用有利于二聚体的稳定存在,这符合实验结晶所需条件.pH值对静电去溶剂化能的影响大于疏水自由能,表明静电作用是造成强酸或强碱条件下二聚体不能稳定存在的主要原因.

The crystal structures of the TGEV 3CL proteinase is used to study the electrostatic and hydrophobic interactions between two monomers. Solving the Poisson-Boltzmanne equation using the finite difference method is used to calculate the electrostatic potential. The solvent accessible surface model is supplied for the molecular surface and hydrophobicity. The electrostatic and hydrophobic interactions are explored in the condition of different PH values. The electrostatic interaction energy, electrostatic desolvation free energy, and hydrophobic desolvation free energy show smaller values when PH values are between 5.5 and 8.5, which indicates that, in the condition, the electrostatic and hydrophobic interaction are favorable to the stability of the TGEV 3CL proteinase dimer. The results are consistent with the experimental condition for the crystallization of the TGEV 3CL proteinase dimer. PH values have stronger influence on the electrostatic desolvation free energy than on the hydrophobic desolvation free energy, which implies that the electrostatic interaction is the key factor to the instability of the TGEV 3Cl proteinase dimer in acid or alkali condition.