Triplex formation between d-CGCTCT and the self-complentary oligonucleotide d-CAATCTCGCGACATTG-spectroscopic investigations

Abstract

We report here studies on triple helix formation by mixed purine-pyrimidine strands with a view to explore the general potential of oligomeric triplex formation as.a recognition phenomenon of DNA sequences. It IS observed that the hexamer d-CGCTCT -3' with a purine at second position forms a stable triplex with a self - complementary DNA duplex d-CAATCTCGCGA- G A TTG-3' in the pH range 5-7, in the presence of 2M NaCI. ^IH NMR spectra in H₂0 solution under these conditions show the imino resonances belonging to the Hoogsteen base pairs in the triplex, Thermodynamic parameters for the triplex formation have been deter- mined by UV spectroscopy.