A hypothesis on the possible contribution of free hypoxanthine and adenine bases in prebiotic amino acid synthesis

Vol.13, No.1 | 2015 | hypothesisjournal.com ABSTRACT Experimental conditions were devised, imitating prebiotic conditions in hydrothermal vents, to examine the possible prebiotic role of free purine bases in the direct synthesis of amino acids. Hypoxanthine, the biochemical precursor of adenine and guanine, was able to capture nitrite ions and be reductively transformed into adenine. Transfer of the exocyclic group of adenine into uracil for cytosine formation was also possible, but the reverse transamination was not observed. In combination with previous work proving the feasibility of reductive amination of pyruvate into alanine by cytosine, it is concluded that the pyrimidine hypoxanthine could have evolutionarily appeared as an efficient capturer of inorganic nitrogen species, passing them to uracil, for further amination of α-keto acids into amino acids. INTRODUCTION It has been proposed that life originated in a hot, acidic, reducing, anaerobic environment, rich in hydrogen gas and nitrogen, sulfur and iron compounds, such as is encountered in hydrothermal vents 1-7.