Electroweak quantum chemistry of alanine: parity violation in gas and condensed phases.

Just how different are the energies of left- and right-handed alanine enantiomers because of parity violation? Substantial advances in electroweak quantum chemistry have provided new answers to this question. The present, advanced calculations lead to the conclusion that numerous previous claims of L-alanine stabilization by parity violation are unjustified. This introduces some extra pepper into current discussions of the origin of biomolecular homochirality. The picture shows a zwitterionic model with conformational changes and solvent effects, as included in the calculations.