Hydrogen cyanide generation from amino acids for prebiotic evolution

Hydrogen cyanide (HCN) is a key precursor for nearly all essential life’s building blocks; therefore, understanding how HCN was sustainably generated on early Earth is of fundamental importance. Previously proposed abiotic routes to HCN require harsh conditions, such as high-energy bombardments; however, living organisms synthesize HCN under mild conditions using amino acids as the sole substrates. Here, we demonstrate the abiotic conversion of amino acids to HCN under ambient, anaerobic aqueous conditions. On manganese dioxide, glycine was converted to HCN with selectivity up to 57%. The concurrent formation of keto acids suggests imine as intermediate, resembling enzymatic carbon-carbon-bond cleavage. As amino acids can be continuously supplied through HCN-independent pathways, these findings suggest that HCN was readily available in aqueous environments to support prebiotic evolution. The simultaneous generation of Kreb’s cycle intermediates suggests amino acids as hub molecules for linking information molecules and carbon protometabolism, expanding their role beyond peptides synthesis.