Nucleic Acids Research, 2003, Vol. 31, No. 24 7150-7158
© 2003 Oxford University Press
Article |
The base pairing properties of 8-aza-7-deaza-2'-deoxyisoguanosine and 7-halogenated derivatives in oligonucleotide duplexes with parallel and antiparallel chain orientation
Laboratorium für Organische und Bioorganische Chemie, Institut für Chemie, Universität Osnabrück, Barbarastr. 7, D-49069 Osnabrück, Germany
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The base pairing properties of oligonucleotide duplexes containing 8-aza-7-deaza-2'-deoxyisoguanosine, its 7-bromo or its 7-iodo derivative are described. The nucleosides were synthesized on a convergent route, protected and converted into phosphoramidites. Oligonucleotides were prepared on a solid-phase and were hybridized to yield duplexes with parallel (ps) or antiparallel (aps) chain orientation. The 8-aza-7-deaza-2'-deoxyisoguanosine-containing duplexes show almost identical base pairing stability as those containing 2'-deoxyisoguanosine, while the 7-substituted derivatives induce a significant duplex stabilization both in ps and aps DNA. Self-complementary duplexes with parallel chain orientation are exceptionally stable due to the presence of 5'-overhangs. The bulky halogen substituents were found to be well accommodated in the grooves both of aps and ps DNA.