Inhibitory activity of thermal copolymers of amino acids for the metal-catalyzed hydrolysis of an RNA dinucleotide

It is well known that the hydrolysis of RNA is substantially catalyzed by several metal ions. Although this fact poses a problem for the RNA world hypothesis, there may have been unknown pathways for the protection of RNA molecules against the hydrolytic degradation under the primitive earth conditions. Thus, we have investigated whether or not thermal copolymers of amino acids (TCAA) inhibit the catalytic activity of metal ions for the RNA hydrolyses; TCAA is a suitable model material for prebiotic protein-like molecules since TCAA involving peptide bonding is readily prepared by heating amino acid mixtures under prebiotic conditions. The activities of metal ions that Fe(III) and Co(II) enhance somewhat the 3′,5′-cytidylylguanosine (C3′pG) hydrolysis and Ce(III) and Eu(III) accelerate greatly the C3′pG hydrolysis were notably reduced by TCAA. This fact indicates that protein-like molecules would have played important roles for the accumulation of RNA under the primitive earth conditions.