© 2004 by Oxford University Press
Novel nucleic acids with left-handed helicity
Discovery Research Laboratories, Nippon Shinyaku Co. Ltd., 3-14-1 Sakura, Tsukuba City, Ibaraki 305-0003, Japan
Oligonucleotides containing a methylene bridge between Nl 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 dichroism spectra 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 right-handed helices. NMR (NOESY) provides supporting evidence for a left-handed conformation of the homo-type dimer. Atomic force microscopy (AFM) indicates a left-handed helical conformation of homo-type dsDNA.