Simulation Studies of Self-replicating Oligoribotides, with a Proposal for the Transition to a Peptide-assisted Stage

A two-substrate Michaelis-Menten mechanism previously proposed for the self-replication of RNA-like oligomers is developed. Differential growth depends on the existence of two pairs of complementary monomers and leads to 2n groups of 2n components each (n is the oligomer size). As n increases the 2n groups tend to overlap with one another, and the efficiency of the process to increase the information content of the strands decreases. In a second stage we suppose that randomly synthesized peptides with one predominant amino acid interacted with the ribotides, increasing the growth rate of some of them, and at the same time had their mean life increased by interactions with other ribotides of the same kinetic group. Natural selection could have preserved a favourable codon-anticodon amino acid correlation, the precursor of the modern genetic code.