INVESTIGATION OF THE PREBIOTIC SYNTHESIS OF AMINO-ACIDS AND RNA BASESFROM CO2 USING FES H2S AS A REDUCING AGENT/

An autotrophic theory of the origin of metabolism and life has been pr oposed in which carbon dioxide is reduced by ferrous sulfide and hydro gen sulfide by means of a reversed citric acid cycle, leading to the p roduction of amino acids. Similar processes hale been proposed for pur ine synthesis. Ferrous sulfide is a strong reducing agent in the prese nce of hydrogen sulfide and can produce hydrogen as web as reduce alke nes, alkynes, and thiols to saturated hydrocarbons and reduce ketones to thiols. However, the reduction of carbon dioxide has not been demon strated. We show here that no amino acids, purines, or pyrimidines are produced from carbon dioxide with the ferrous sulfide and hydrogen su lfide system. Furthermore, this system does not produce amino acids fr om carboxylic acids by reductive amination and carboxylation. Thus, th e proposed autotrophic theory, using carbon dioxide, ferrous sulfide, and hydrogen sulfide, lacks the robustness needed to be a geological p rocess and is, therefore, unlikely to have played a role in the origin of metabolism or the origin of life.