Linear response theory coupled to molecular dynamics simulations with an explicit solvent representation is used to derive fractional contributions of amino acid residues to the solvation of proteins. The new fractional methods developed here are compared with standard approaches based on empirical 1D and 3D statistical potentials, as well as with estimates obtained from the analysis of classical molecular interaction potentials. The new fractional methods, which have a clear physical basis and explicitly account for the effects due to protein structure and flexibility, provide an accurate picture of the contribution to solvation of different regions of the protein.