Acta Phys. -Chim. Sin. ›› 2010, Vol. 26 ›› Issue (10): 2813 -2820.doi: 10.3866/PKU.WHXB20101011

• BIOPHYSICAL CHEMISTRY • Previous Articles     Next Articles

Effects ofMolecular Volume and Fractional Polar Surface Area of Osmolytes on the Thermal Stability of Chymotrypsin Inhibitor 2

LIU Fu-Feng, JI Luo, DONG Xiao-Yan   

  1. Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, P. R. China; Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin University, Tianjin 300072, P. R. China
  • Received:2010-06-28 Revised:2010-07-19 Published:2010-09-27
  • Contact: DONG Xiao-Yan
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (20636040, 20876111, 20906068), National Key Basic Research Program of China (973) (2009CB724705), Natural Science Foundation of Tianjin from Tianjin Municipal Science and Technology Commission, China (08JCZDJC17100), and Independent Innovation Foundation of Tianjin University, China.


We correlated the protective ability of osmolytes on proteins with their fractional polar surface area (fpSA) and molecular volume (V). Thus, both parameters need to be considered when the protective ability of osmolytes is analyzed. We carried out molecular dynamics simulations of the chymotrypsin inhibitor 2 (CI2) in different osmolytes to probe the molecular basis of the stabilizing effect. Based on the simulation data, a one-dimensional structure parameter was first calculated. We then used a statistical bivariate fit model to obtain a theoretical model, which represents the stability capacity of the osmolytes. Finally, the model was used to analyze the correlation between the two parameters (fpSA and V) and the protective ability of the osmolytes. We found that the one-dimensional structure parameter characterized the protective ability of the osmolytes well. Using this model, the protective stability of the osmolytes can be analyzed accurately. The inclusion of V and the two-order term of fpSA greatly increases the accuracy of the model. The protective capacity of the osmolytes increases with V. In addition, we introduced the two-order term of fpSA into the fit formula. We found that the fpSA of the osmolytes is negatively correlated with its protective ability when it is less than 0.7. However, when the fpSA of the osmolytes is larger than 0.7, it is positively correlated with its protective ability.

Key words: Molecular dynamics simulation, Protein stability, Osmolyte, Fractional polar surface area, Molecular volume


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