Cross‐Catalysis and Weak Interactions: Keys to the Chiral Polarization of the Biosphere

ABSTRACT Molecular homochirality — the uniformity of chirality in biological molecules — is a fundamental feature of life, yet its origins remain unresolved. The correspondence between the chirality of biological monomers on Earth and that observed in ancient meteorites implies a systematic selection of chirality sign in prebiotic chemistry, rather than a stochastic process. While classical theories attribute symmetry breaking to chiral autocatalysis, such self‐amplifying processes are rare and have not been empirically demonstrated in the synthesis of amino acids and carbohydrates. In contrast, chiral cross‐catalysis between amino acids and carbohydrates — a mechanism consistent with known chemical behavior — could similarly amplify chiral purity. However, cross‐catalysis alone cannot determine the chirality sign due to its inherent symmetry, leaving the origin of the initial bias unexplained. Although weak interactions have been proposed as a potential source of this bias, their effects are theoretically negligible, raising questions about their sufficiency. Our kinetic analysis of cross‐catalytic systems reveals that even an infinitesimal preference for left‐handed amino acids and right‐handed carbohydrates could be sufficient to establish the homochirality observed in life. This mechanism provides a plausible link between prebiotic chemistry and the homochirality of the biosphere, offering a potential resolution to this longstanding enigma.