title: Phosphorothioate oligonucleotide-directed triple helix formation.
abstract: Phosphorothioate oligodeoxyribonucleotides were tested for their ability to recognize double-helical DNA in two distinct triple helix motifs. Purine-rich oligonucleotides containing a diastereomeric mixture of phosphorothioate or stereoregular (all RP) phosphorothioate linkages are shown to form triple-helical complexes with affinities similar to those of the corresponding natural phosphodiester oligonucleotides. In contrast, pyrimidine-rich phosphorothioate oligonucleotides containing a mixture of diastereomeric or stereoregular (all RP) linkages do not bind to double-helical DNA with measurable affinity. These observations have implications for triple helix structure and for biological applications.
authors.affiliation: Division of Biology, California Institute of Technology, Pasadena 91125.
authors.forename: J G
authors.initials: JG
authors.lastname: Hacia
authors.forename: B J
authors.initials: BJ
authors.lastname: Wold
authors.forename: P B
authors.initials: PB
authors.lastname: Dervan
mesh_terms: D001483:Base Sequence; D003850:Deoxyribonuclease I; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry*; D013873:Thionucleotides / Q000737:chemistry*
chemical_list: D009838:Oligodeoxyribonucleotides; D013873:Thionucleotides; D003850:Deoxyribonuclease I