title: Isoguanosine substitution of conserved adenosines in the hammerhead ribozyme.
abstract: Isoguanosine has been incorporated into a 34-mer hammerhead ribozyme by the solid-phase phosphoramidite method, using an acetamidine base protecting group. The activity of the hammerhead ribozyme when singly mutated to isoguanosine at the adenosine positions 6, 9, and 13 was 1-2-fold less than the wild-type activity. Mutations to 2-aminopurine ribonucleoside at positions 9 and 13 were 5-fold reduced in activity, but that at position 6 was approximately 30-fold reduced. These results support the view that the 6-amino functions of A6, A9, and A13 are not very important for catalysis. The 2-position of A6 tolerates a carbonyl function but not an amino group, whereas A9 and A13 tolerate both functional groups. The tolerance of a 2-amino group at A9 and A13 makes G(anti)/A(anti) Watson-Crick type base mispairing for G12/A9 and A13/G8 unlikely.
authors.affiliation: Max-Planck-Institut für experimentelle Medizin, Göttingen, Germany.
authors.forename: M M
authors.initials: MM
authors.lastname: Ng
authors.forename: F
authors.initials: F
authors.lastname: Benseler
authors.forename: T
authors.initials: T
authors.lastname: Tuschl
authors.forename: F
authors.initials: F
authors.lastname: Eckstein
mesh_terms: D015075:2-Aminopurine / Q000737:chemistry; D000241:Adenosine / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000578:Amidines / Q000737:chemistry; D001483:Base Sequence; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D004591:Electrophoresis, Polyacrylamide Gel; D006151:Guanosine / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis* / Q000737:chemistry; D016337:RNA, Catalytic / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D014361:Trypsin Inhibitors / Q000737:chemistry
chemical_list: D000578:Amidines; D009838:Oligodeoxyribonucleotides; D016337:RNA, Catalytic; D014361:Trypsin Inhibitors; D006151:Guanosine; C008184:isoguanosine; D015075:2-Aminopurine; D000241:Adenosine; C023731:acetamidine