Effect of chiral helical force field on molecular helical enantiomers and possible origin of biomolecular homochirality

Abstract

Biomolecular homochirality means that the amino acids in proteins, and sugars in nucleic acids, occur in one form: amino acids in L-form and sugars in D-form. So far, the reason why these molecules have such uniform chirality is not known. In this paper, it is suggested that a net natural chiral right-handed helical force field, produced by the Earth's orbital chirality (EOC), could affect the stability of molecular helical enantiomers and make the right-handed helical enantiomers more stable than their left-handed enantiomers, so terrestrial biological systems must select both right-handed helical nucleic acids based on D-sugars, and proteins based on L-amino acids. In given conditions, the maximum energy difference between biomolecular helical enantiomers ( ΔE max ⋎E left − E right ∥ ) caused by the EOC may be calculated theoretically to be in the order: B-DNA > A-RNA > A-DNA ⪢ α-protein > β-protein. Our experimental results strongly supported the hypothesis that the EOC could cause the spontaneous selection and amplification of right-handed helical enantiomers and could be the origin of homochirality on the Earth.