title: Unusual thermal stability of RNA/[RP-PS]-DNA/RNA triplexes containing a homopurine DNA strand.
abstract: Homopurine deoxyribonucleoside phosphorothioates, as short as hexanucleotides and possessing all internucleotide linkages of RP configuration, form a triple helix with two RNA or 2'-OMe-RNA strands, with Watson-Crick and Hoogsteen complementarity. Melting temperature and fluorescence quenching experiments strongly suggest that the Hoogsteen RNA strand is parallel to the homopurine [RP-PS]-oligomer. Remarkably, these triplexes are thermally more stable than complexes formed by unmodified homopurine DNA molecules of the same sequence. The triplexes formed by phosphorothioate DNA dodecamers containing 4-6 dG residues are thermally stable at pH 7.4, although their stability increases significantly at pH 5.3. FTIR measurements suggest participation of the C2-carbonyl group of the pyrimidines in the stabilization of the triplex structure. Formation of triple-helix complexes with exogenously delivered PS-oligos may become useful for the reduction of RNA accessibility in vivo and, hence, selective suppression/inhibition of the translation process.
authors.affiliation: Department of Bioorganic Chemistry, Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Łódź, Poland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Guga
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Boczkowska
authors.forename: Magdalena
authors.initials: M
authors.lastname: Janicka
authors.forename: Anna
authors.initials: A
authors.lastname: Maciaszek
authors.forename: Slawomir
authors.initials: S
authors.lastname: Kuberski
authors.forename: Wojciech J
authors.initials: WJ
authors.lastname: Stec
mesh_terms: D001665:Binding Sites; D003198:Computer Simulation; D004247:DNA / Q000737:chemistry*; D004268:DNA-Binding Proteins / Q000737:chemistry; D004355:Drug Stability; D008956:Models, Chemical; D009429:Netropsin / Q000737:chemistry*; D009691:Nucleic Acid Denaturation; D011485:Protein Binding; D011687:Purines / Q000737:chemistry*; D012313:RNA / Q000737:chemistry*; D013696:Temperature
chemical_list: D004268:DNA-Binding Proteins; D011687:Purines; C051802:triplex DNA; D012313:RNA; D009429:Netropsin; D004247:DNA