Nonenzymatic oligomerization of ribonucleotides: Towards in vitro selection experiments

Inspired by the polymerase chain reaction, orthogonal primer-template pairs have been applied in template-controlled oligomerization experiments with Orgel's imidazole-activated ribonucleotide-5'-phosphates. Variation of the linker length allowed us to monitor the extension of both primers simultaneously on a DNA sequencer. Sets of hexapyrimidine primers were found that are capable of inducing the reciprocal synthesis of each other's binding site. Considerable cross-inhibition by different monomers was observed. However, this effect is a function of primer sequence and can disappear in favorable cases. With random sequences introduced into the templates, selection experiments are within reach. First results are reported below.