We have shown that 6-substituted adenines are easily synthesized together with adenine during an HCN polymerization. In addition 6-methyl adenine can be efficiently synthesized from adenine by heating with CH 3 NH 2 under the concentrating conditions of the drying lagoon model of prebiotic synthesis.
Similar reactions take place with amines and amino acids.
These results suggest that methylated adenine and guanine, which are components of tRNA and rRNA, were constituents of the primitive ocean and may have played a role in the first genetic material. This raises the possibility that C was not in the first genetic material. A two base nucleic acid is unlikely because of self-structure. Cytosine might be usable if there was a concentration mechanism for it or there was a very rapid origin of life. The mechanism of formation of EDMA may be a Strecker synthesis with ethylene diamine, which we have shown to be a spark discharge product.