Empirical Models of Hydration of Small Peptides

Simple empirical potentials have been used to calculate hydration sites of C5, C7eq. and αR conformers of Ac-L-Ala-NHMe. The formation of specific water bridges connecting two peptide groups are then displayed. The coexistence of individual sites and of water bridges have been then analyzed for a tetrapeptide: Ac-L-Thr-L-Thr-L-Ser-LAsp. NHMe folded into a β-turn I and for a cyclic dipeptide c(L-Thr-L-His). Side chain — side chain, side chain — backbone and backbone — backbone single or double water bridges, are proposed to be specific modes of hydration of peptides, which are not necessarily maintened in optimized configurations of the first hydration shells. The present structural aspects of hydration will serve for further static and dynamic studies of peptides conformations in crystals and in solution.