From Weak Chiral Bias to Homochirality: A Recombination-Driven Mechanism in Prebiotic Aqueous Systems

The origin of biomolecular homochirality remains one of the key unresolved problems in theories of the origin of life. Amino acids of meteoritic origin exhibit a small but systematic enantiomeric excess consistent with biological systems. Previous studies have shown that homochirality may arise through nonequilibrium mechanisms of chiral amplification. Here, we propose a physically realizable mechanism of homochiralization based on the continuous influx of weakly chirally polarized amino acids into large, shallow aqueous reservoirs and the recombination of antipodal enantiomers with the removal of poorly soluble heterochiral dimers (Figure 1). We show that a small initial enantiomeric excess is amplified to near-complete homochirality, with deviation 1 - ee ~3 × (10^-6 - 10^-11), whereas the concentration of the dominant enantiomer reaches ~1 nM-3 mМ, sufficient for prebiotic chemistry. The mechanism operates in stationary aqueous environments and is complementary to previously studied evaporation-driven scenarios, thereby expanding the range of plausible pathways to homochirality under prebiotic conditions.