Oligonucleotides incorporating 8-aza-7-deazapurines: synthesis and base pairing of nucleosides with nitrogen-8 as a glycosylation position

Autor(en): He, JL
Seela, F
Stichwörter: 8-AZA-7-DEAZAADENINE; Chemistry; Chemistry, Organic; DNA BACKBONE; DT; DUPLEX DNA; HELIX; PYRAZOLO<3,4-D>PYRIMIDINES; STABILITY
Erscheinungsdatum: 2003
Herausgeber: ROYAL SOC CHEMISTRY
Journal: ORGANIC & BIOMOLECULAR CHEMISTRY
Volumen: 1
Ausgabe: 11
Startseite: 1873
Seitenende: 1883
Zusammenfassung: 
Oligonucleotides incorporating the unusually linked 8-aza-7-deazapurine N-8-(2'-deoxyribonucleosides) 3a,b ( purine and 6-amino-2-chloropurine analogues) were used as chemical probes to investigate the base pairing motifs of the universal nucleoside 8-aza-7-deazapurin-6-amine N-8-(2'-deoxyribofuranoside) 2 (adenine analogue) and that of the 2,6-diamino compound 1. Owing to the absence of an amino group on the nucleoside 3a the low stability of oligonucleotide duplexes incorporating this compound opposite to the four canonical DNA-constituents indicate hydrogen bonding and base pairing for the universal nucleosides 1 and 2 which form much more stable duplexes. When the 6-amino-2-chloro-8-aza-7-deazapurine nucleoside 3b replaces 1 and is located at the same positions, two sets of duplexes are formed (i) high T-m duplexes with 3b located opposite to dA or dC and (ii) low T-m duplexes with 3b located opposite to dG or dT. These results are due to the steric clash of the 2-chloro substituent of 3b with the 2-oxo group of dT or the 6-oxo group of dG while the 2-halogeno substituents are well accommodated in the base pairs formed with dA or dC. For comparison duplexes incorporating the regularly linked nucleosides 4-6a, b containing the same nucleobases as those of 1-3a,b were studied.
ISSN: 14770520
DOI: 10.1039/b301608k

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