Solvation energy and thermal stability of hydrophilization-modified alpha-chymotrypsin

As reported in the literature [Mozhaev et al. (1988), Eur. J. Biochem. 173, 147-154], when a series of modifiers, especially the cyclic anhydrides of pyromellitic and mellitic acids, are introduced into each lysine located in the alpha-chymotrypsin (CT) surface, a substantial hydrophilization of the enzyme surface can occur and remarkable stabilization effects of modified enzymes can be obtained. In this paper, four models are applied to calculate the solvation energy of native and the modified CT based on their tertiary structures, which can be built by the CVFF force field. Analyzing the relationship between the solvation energy and the thermal stability in detail, we find that the results of three solvation energy models (Ooi model, WE-1 model, and WE-2 model) can be used to illustrate the relative stability among these enzymes qualitatively. The present study should be of practical value as well as of some theoretical interest.