Interaction of DNA hairpin loops and a complementary strand by a triplet of base pairs

Hypothesis of non-enzymatic recognition of primordial tRNA and mRNA precursors is experimentally approached. DNA hairpins containing a different number of deoxyguanosine residues in the loop are analyzed for their binding ability to a chemically fixed single-strand of oligo(dC). In presence of small Mg2+ concentration a hairpin with five dG residues in the loop is adsorbed to affinity matrix. Comparison of elution temperatures of hairpin oligonucleotides with those of single-stranded oligoguanylic acids with length of the loop indicates, that smallest loop able to bind forms a triplet of base pairs.