Prebiotic Synthesis of L-Homochiral Peptides on Primordial Earth

The origin of biological homochirality remains a central enigma in astrobiology. The emergence of a homochiral world necessitates two key processes: initial symmetry breaking and subsequent chiral selection and amplification during abiotic polymerization. This study focuses on the latter, specifically investigating whether an initial chiral environment could have influenced the selectivity of prebiotic peptide synthesis. We demonstrate a novel, prebiotically plausible pathway for homochiral peptide formation utilizing amino acid amides (AA-NH ₂ ) on early Earth. We observed that L-AA-NH ₂ environments induce a robust, consistent stereochemical bias, which leads to enriched L-homochiral peptide synthesis. This bias is significantly amplified during oligomerization, achieving near-absolute L-homochirality. D-AA-NH ₂ systems, however, exhibited environmentally contingent, fluctuating selectivity. Crucially, peptide formation from Gly-NH ₂ in racemic conditions was strongly inhibited, demonstrating the power of subtle chiral induction in driving homochirality. Our results support a model where initial chirality influences the selectivity of peptide polymerization during the origin of life, providing a potential pathway for generating the biological homochirality essential for life and offering new insights into its potential for life elsewhere in the cosmos.