title: Homo-N-oligonucleotides (N1/N9-C1' methylene bridge oligonucleotides): nucleic acids with left-handed helicity.
abstract: Oligonucleotides containing a methylene bridge between N1 or N9 of the heterocyclic base and C1' of the pentofuranosyl ring (homo-N-oligonucleotides) were synthesized. Melting curves revealed that such homo-type oligomers could cross-pair with complementary homo-type or natural oligomers. Circular-dichroic studies provide evidence that the homo-type dimers have a left-handed stacked conformation and further suggest that single-stranded and double-stranded homo-type oligomers adopt a left-handed conformation, while duplexes with natural oligomers or nucleic acids form RNA-like right-handed helices. NMR spectroscopy (NOESY) provides supporting evidence for a left-handed stacked conformation of the homo-type dimer, while atomic force microscopy indicates a left-handed helical conformation of homo-type dsDNA. Homo-type dimers and oligomers showed high resistance to digestion by snake-venom and calf-spleen phosphodiesterases and nuclease S1.
authors.affiliation: Discovery Research Laboratories, Nippon Shinyaku Co. Ltd, 3-14-1 Sakura, Tsukuba City, Ibaraki 305-0003, Japan. k.ishiyama@po.nippon-shinyaku.co.jp
authors.forename: Kouichi
authors.initials: K
authors.lastname: Ishiyama
authors.forename: Gerald E
authors.initials: GE
authors.lastname: Smyth
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Ueda
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Masutomi
authors.forename: Tadaaki
authors.initials: T
authors.lastname: Ohgi
authors.forename: Junichi
authors.initials: J
authors.lastname: Yano
mesh_terms: D002942:Circular Dichroism; D018625:Microscopy, Atomic Force; D008958:Models, Molecular; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D009690:Nucleic Acid Conformation; D009696:Nucleic Acids / Q000737:chemistry* / Q000378:metabolism; D009841:Oligonucleotides / Q000138:chemical synthesis* / Q000737:chemistry* / Q000378:metabolism; D015719:Single-Strand Specific DNA and RNA Endonucleases / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature
chemical_list: D009696:Nucleic Acids; D009841:Oligonucleotides; D015719:Single-Strand Specific DNA and RNA Endonucleases