The next most important step in research on prebiotic organic synthesis was the demonstration by John OrÃ that the nucleic acid purine base , adenine , was formed by the simple heating of solutions of ammonium cyanide . Apart from the Millerâ `` Urey experiment , the next most important step in research on prebiotic organic synthesis was the demonstration by Joan OrÃ that the nucleic acid purine base , adenine , was formed by heating aqueous ammonium cyanide solutions .