Prebiotic Inhibitory Activity of Protein-Like Molecules to the Template-Directed Formation of Oligoguanylate from Guanosine 5′-Monophosphate 2-Methylimidazolide on a Polycytidylic Acid Template

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Abstract The influence of thermal copolymers of amino acids (TCAA) as a primitive protein enzyme model has been investigated to detect catalytic and/or inhibitory activities on the template-directed formation of oligoguanylate (oligo(G)) from guanosine 5′-monophosphate 2-methylimidazolide (2-MeImpG) on a polycytidylic acid template (poly(C)) (TD reaction). Different amino acids and compositions were used to prepare TCAAs. These TCAAs were characterized by gel filtration HPLC and the composition analysis of amino acids using phenyl isothiocyanate. It was found that TCAA including His (TCAA-His) has inhibitory activity to the TD reaction, in which TCAA-His accelerates the hydrolysis of 2-MeImpG. Other types of TCAAs, including Gly, Ala, Val, Glu, and Asp, also accelerate the formation of P1,P2-bis(5′-guanosyl) diphosphate (G5′ppG) and G5′ppG incorporated oligo(G)s during the TD reaction at high concentrations of TCAAs. These reactions are considered as primitive enzyme models for the hydrolysis of nucleotide monomer and the formation of pyrophosphate-containing oligo(G).