Atomic solvation parameters applied to molecular dynamics of proteins in solution.

A solvation energy function for use in the molecular simulation of proteins is proposed. It is based on the accessible surface areas of atoms in the protein and on atomic solvation parameters derived from empirical vapor-to-water free energies of transfer of amino acid side-chain analogs. The energy function and its derivatives were added to the CHARMM molecular simulation program (Brooks, B.R., Bruccoleri, R.E., Olafson, B.D., States, D.J., Swaminathan, S., & Karplus, M., 1983, J. Comput. Chem. 4(2), 187-217). The effect of the added energy term was evaluated by 110 ps of molecular dynamics on the 26-residue protein melittin. The melittin monomer and tetramer were studied both with and without the added term. With the added energy term the monomer partially unfolded, while the secondary structure of the tetramer was preserved, in agreement with reported experiments (Brown, L.R., Lauterwein, J., & Wuethrich, K., 1980, Biochim. Biophys. Acta 622(2), 231-244; Lauterwein, J., Brown, L.R., & Wuethrich, K., 1980, Biochim. Biophys. Acta 622(2), 219-230).