期刊
JOURNAL OF CHEMICAL PHYSICS
卷 132, 期 22, 页码 -出版社
AMER INST PHYSICS
DOI: 10.1063/1.3453713
关键词
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资金
- Natural Science Foundation of China [20636040, 20876111, 20906068]
- National Basic Research Program of China (973 Program) [2009CB724705]
- Natural Science Foundation of Tianjin from Tianjin Municipal Science and Technology Commission [08JC-ZDJC17100]
Molecular dynamics simulations of chymotrypsin inhibitor 2 in different polyols (glycerol, xylitol, sorbitol, trehalose, and sucrose) at 363 K were performed to probe the molecular basis of the stabilizing effect, and the data in water, ethanol, and glycol were compared. It is found that protein protection by polyols is positively correlated with both the molecular volume and the fractional polar surface area, and the former contributes more significantly to the protein's stability. Polyol molecules have only a few direct hydrogen bonds with the protein, and the number of hydrogen bonds between a polyol and the protein is similar for different polyols. Thus, it is concluded that the direct interactions contribute little to the stabilizing effect. It is clarified that the preferential exclusion of the polyols is the origin of their protective effects, and it increases with increasing polyol size. Namely, there is preferential hydration on the protein surface (2 angstrom), and polyol molecules cluster around the protein at a distance of about 4 angstrom. The preferential exclusion of polyols leads to indirect interactions that prevent the protein from thermal unfolding. The water structure becomes more ordered with increasing the polyol size. So, the entropy of water in the first hydration shell decreases, and a larger extent of decrease is observed with increasing polyol size, leading to larger transfer free energy. The findings suggest that polyols protect the protein from thermal unfolding via indirect interactions. The work has thus elucidated the molecular mechanism of structural stability of the protein in polyol solutions. (C) 2010 American Institute of Physics. [doi:10.1063/1.3453713]
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