Magnetic Field Effects on Chiral Selection in Peptide Formation Mediated by N-aa-AMP

Peptide synthesis in modern biology proceeds via aminoacyl adenylates (5′-aa-AMP), which are central to both peptide bond formation and chiral recognition. Inspired by this mechanism, our previous work showed that amino acids, adenosine, and trimetaphosphate can spontaneously form N-aminoacyl adenylates (N-aa-AMP) under aqueous conditions, suggesting N-aa-AMP as a plausible prebiotic precursor of 5′-aa-AMP. Importantly, N-aa-AMP formation exhibits intrinsic chiral selectivity, with L-amino acids preferentially pairing with D-nucleosides and vice versa, raising the question of whether such selectivity persists during peptide synthesis.We previously investigated peptide formation between N-Phe-F-AMP and racemic amino acids at pH 9 and 37 °C. N-L-Phe-F-AMP preferentially reacts with L-amino acids, promoting homochiral dipeptide formation, while N-D-Phe-F-AMP shows the corresponding mirror selectivity. This behavior is consistent across several amino acids (Ile, Leu, Ala, Val, and Pro), with homochiral excesses ranging from 12.04% to 67.84%, demonstrating that N-aa-AMP intrinsically directs chiral selection during peptide formation. Here, we investigated the effect of magnetic fields on this process. Compared with moderate magnetic fields (MMF), geomagnetic (GMF) and hypo-magnetic (HMF) conditions significantly enhance chiral selectivity, with the strongest amplification observed under HMF. These results suggest that the weak magnetic environment of early Earth may have influenced reaction dynamics and intermolecular interactions, thereby facilitating chiral amplification during prebiotic peptide synthesis.Overall, our findings indicate that N-aa-AMP can promote homochiral peptide formation under enzyme-free and metal-free prebiotic conditions, while magnetic fields may serve as an additional physical factor modulating chiral selection. This work introduces magnetic effects into prebiotic reaction networks and provides new insights into the emergence of biological homochirality.