Oligo(dG)12-18 aggregates result in non-homogeneity of oligo(dG)12-18.poly(C) type primer-template

Abstract

Studies on the absorption spectra of equimolar solutions of oligo(dG)12-18 and poly(C), poly(Cm) or poly(Ce) showed that only 13%, 3% and 3% of base pairs, repectively, form complexes. Upon centrifugation of oligo(dG)12-18 with a molar excess of poly(C) of poly(Cm) in an analytical and a preparative centrifuge, it was found that only a part of oligodeoxynucleotide sediments with the polynucleotide, i.e. more rapidly than oligo(dG)12-18, poly(C) or poly(Cm). Products of binding of oligo(dG)12-18 with poly(C), poly(Cm) or poly (Ce) direct the synthesis of poly (dG) by AMV reverse transcriptas in accordance with the reported characteristics of these primer-templates, as well as of the enzyme. These observations suggest that the solutions of oligo(dG)12-18 with (polyC) or its analogues, commonly used as primer-templates of RNA- and DNA-directed DNA polymerases, contain a polynucleotide, to which oligo(dG)12-18 aggregates are bound through a few nucleotides chains shorter than 12-18 residues. These chains of oligo(dG)12-18 containing the 3'-OH ends are capable of of initiating the reaction with DNA POLYMERASES.