The biogeochemical cycle of the adsorbed template. II: Selective adsorption of mononucleotides on adsorbed polynucleotide templates.

Experimental results are presented for the verification of the specific interaction step of the 'adsorbed template' biogeochemical cycle, a simple model for a primitive prebiotic replication system. The experimental system consisted of gypsum as the mineral to which an oligonucleotide template attaches (Poly-C or Poly-U) and 5'-AMP, 5'-GMP, 5'-CMP and 5'-UMP as the interacting biomonomers. When Poly-C or Poly-U were used as adsorbed templates, 5'-GMP and 5'-AMP, respectively were observed to be the most strongly adsorbed species. Moreover, there exists a direct quantitative relationship between the quantity of cytidine or uracil residues in the adsorbed state and the amount of the complementary mononucleotide that is attached to it. NaCl added to the system in order to create conditions of high ionic strength seems to enhance the selectivity of the adsorption of the monmucleotides to these adsorbed templates.