Orientation of amino acid side chains: intraprotein and solvent interactions

The conformation, i.e., three-dimensional structure, of a native protein molecules is mainly the resultant of noncovalent interactions of atoms of the peptide backbone and of the amino acid side chains with each other and with the solvent environment. In fact, it is generally accepted that the native conformation of the protein molecule in a given environment is the one for which the Gibbs free energy of the entire system (consisting of the protein and its environment) is a minimum.