title: A novel concept for ligand attachment to oligonucleotides via a 2'-succinyl linker.
abstract: Conjugation of ligands to antisense oligonucleotides is a promising approach for enhancing their effects. In this report, a new method for synthesizing oligonucleotide conjugates is described. 2'-Amino-2'-deoxy-5'-dimethoxytrityl-uridine was select ively acylated with a succinic acid linker at the 2' position. This compound was incorporated at the 3' end of an oligonucleotide corresponding to the sequence of Oblimersen. The carboxyl group was protected for oligonucleotide synthesis as a benzyl ester, which could be selectively cleaved at the solid phase by a catalytic phase transfer reaction using palladium nanoparticles as catalyst. An oligonucleotide-fluorescein conjugate was prepared by condensation of aminofluorescein. Circular dichroism spectroscopic experiments showed a B-DNA type structure. The melting temperature of the duplex was only slightly lower than that of Oblimersen. Biological activity measured by western blotting resulted in a Bcl-2 target downregulation nearly identical to that of control Oblimersen on human melanoma cells, proving that this method is attractive for the binding of ligands located in the minor groove.
authors.affiliation: Institute for Pharmaceutical Chemistry, Universität Wien, Austria.
authors.forename: Johannes
authors.initials: J
authors.lastname: Winkler
authors.forename: Ernst
authors.initials: E
authors.lastname: Urban
authors.forename: Doris
authors.initials: D
authors.lastname: Losert
authors.forename: Volker
authors.initials: V
authors.lastname: Wacheck
authors.forename: Hubert
authors.initials: H
authors.lastname: Pehamberger
authors.forename: Christian R
authors.initials: CR
authors.lastname: Noe
mesh_terms: D001483:Base Sequence; D045744:Cell Line, Tumor; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D003062:Codon / Q000235:genetics; D004247:DNA / Q000737:chemistry / Q000235:genetics; D006801:Humans; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009691:Nucleic Acid Denaturation; D016376:Oligonucleotides, Antisense / Q000737:chemistry* / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D044366:Transition Temperature; D014529:Uridine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry* / Q000235:genetics
chemical_list: D003062:Codon; D008024:Ligands; D016376:Oligonucleotides, Antisense; D019253:Proto-Oncogene Proteins c-bcl-2; D004247:DNA; D014529:Uridine