Scheme 2From: Stabilization of zwitterionic versus canonical proline by water moleculesGradual increase of water to interact with different proline conformers: a P A 3W I → P A 4W I → P A 5W I , b P B 3W I → P B 4W I → P B 5W I and c P C 3W I → P C 4W I → P C 5W I . Relative energies (kcal/mol) are given in parentheses, using P B nW I as benchmark (n = 3, 4, 5). H-bonds are marked with dashed lines Back to article page