A1 Refereed original research article in a scientific journal
Utilization of intrachain 4 '-C-azidomethylthymidine for preparation of oligodeoxyribonucleotide conjugates by click chemistry in solution and on a solid support
Authors: Kiviniemi A, Virta P, Lonnberg H
Publisher: AMER CHEMICAL SOC
Publication year: 2008
Journal:: Bioconjugate Chemistry
Journal name in source: BIOCONJUGATE CHEMISTRY
Journal acronym: BIOCONJUGATE CHEM
Volume: 19
Issue: 8
First page : 1726
Last page: 1734
Number of pages: 9
ISSN: 1043-1802
DOI: https://doi.org/10.1021/bc800221p
Abstract
4'-C-Azidomethylthymidine 3'-(H-phosphonate) monomer (10) was synthesized in high yield and three such monomers were incorporated by the H-phosphonate coupling into a 15-mer oligodeoxyribonucleotide. The unmodified 2'-deoxynucleosides could be coupled by either the H-phosphonate or phosphoramidite chemistry, indicating that the Staudinger reaction between the azido group and the phosphoramidite reagent severely hampered the coupling only when it took place intramolecularly. After chain assembly, three alkynyl group bearing ligands, viz., propargyl 2,3,4,6-tetra-O-acetyl-alpha-D-mannopyranoside (2), N-(4-[N-(trifluoroacetyl)aminomethyl]benzyl}-4-pentynamide (3) and N-1,N-3,N-2-tris(trifluoroacetyl)-N-6'-(4-pentynoyl)neamine (4), were conjugated to the azido groups of the oligonucleotide by click chemistry both on a solid support and in solution. The products were deprotected by conventional ammonolysis and purified by HPLC chromatography. Melting temperature studies revealed that the mannose conjugated oligonucleotides formed more stable duplexes with 2'-O-methyl RNA than with DNA strand. With 2'-O-methyl RNA, a slight destabilization compared to an unmodified sequence was observed at low ionic strength, while at high salt content, the manno-conjugation was stabilizing.
4'-C-Azidomethylthymidine 3'-(H-phosphonate) monomer (10) was synthesized in high yield and three such monomers were incorporated by the H-phosphonate coupling into a 15-mer oligodeoxyribonucleotide. The unmodified 2'-deoxynucleosides could be coupled by either the H-phosphonate or phosphoramidite chemistry, indicating that the Staudinger reaction between the azido group and the phosphoramidite reagent severely hampered the coupling only when it took place intramolecularly. After chain assembly, three alkynyl group bearing ligands, viz., propargyl 2,3,4,6-tetra-O-acetyl-alpha-D-mannopyranoside (2), N-(4-[N-(trifluoroacetyl)aminomethyl]benzyl}-4-pentynamide (3) and N-1,N-3,N-2-tris(trifluoroacetyl)-N-6'-(4-pentynoyl)neamine (4), were conjugated to the azido groups of the oligonucleotide by click chemistry both on a solid support and in solution. The products were deprotected by conventional ammonolysis and purified by HPLC chromatography. Melting temperature studies revealed that the mannose conjugated oligonucleotides formed more stable duplexes with 2'-O-methyl RNA than with DNA strand. With 2'-O-methyl RNA, a slight destabilization compared to an unmodified sequence was observed at low ionic strength, while at high salt content, the manno-conjugation was stabilizing.
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