Prebiotic phosphorylation. II-nucleotide synthesis in the reaction system apatite-cyanogen-water

The phosphorylation of thymidine has been studied in a model evaporating pond environment. Evaporation of dilute solutions of thymidine and ammonium oxalate in the presence of apatite leads to the synthesis of nucleotides. The presence of organic compounds such as cyanamide or urea substantially increases the yields of products. Solutions of cyanogen, when heated and evaporated in the presence of nucleoside and apatite, produce similarly high yields of nucleotide without added condensing agents. The mechanism of the reaction appears to involve the hydrolysis of cyanogen to produce ammonium oxalate and urea, among other products. An evolutionary continuum leading from the cosmically abundant CN moiety to the establishment of conditions favorable for phosphorylation on the primitive earth is suggested.