Parity-violating energy differences of chiral minerals and the origin of biomolecular homochirality

Abstract

The biochemistry of terrestrial organisms is based on chiral (handed) molecules, with one of the two possible series of enantiomers (mirror-image isomers) being predominant. Specifically, terrestrial biochemistry is homochirally supported by L-α-amino acids and D-sugars to the almost complete exclusion of the enantiomeric D-α-amino acids and L-sugars. This particular homochiral selection may be a result of very small differences between the electronic energies of enantiomeric prebiotic molecules due to the parity-violating weak interactions. The energy differences are, however, so small for simple chiral molecules, that the propagation of homochirality would require a dissymmetry amplification mechanism involving both large quantities of reactants and a long reaction time. An alternative theory, presented here, considering the effects of the parity-violating weak interactions in crystalline enantio-selective prebiotic catalysts, such as the clay silicates, may require considerably less amplification.