Base-pairing, tautomerism, and mismatch discrimination of 7-halogenated 7-deaza-2 `-deoxylsoguanosine: Oligonucleotide duplexes with parallel and antiparallel chain orientation

Autor(en): Seela, F
Peng, XH
Li, H
Stichwörter: 2'-DEOXYISOGUANOSINE; 7-DEAZA-2'-DEOXYISOGUANOSINE; Chemistry; Chemistry, Multidisciplinary; DERIVATIVES; ENZYMATIC INCORPORATION; FORM; ISOCYTOSINE; ISOGUANINE-CYTOSINE; ISOGUANOSINE; OPPOSITE 2-HYDROXYADENINE; STRANDED DNA
Erscheinungsdatum: 2005
Herausgeber: AMER CHEMICAL SOC
Journal: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
Volumen: 127
Ausgabe: 21
Startseite: 7739
Seitenende: 7751
Zusammenfassung: 
Oligonucleotides containing 2'-deoxyisoguanosine (1, iG(d)), 7-deaza-2'-deoxyisoguanosine (2, c(7)iG(d)), and its 7-halogenated derivatives 3 and 4 were synthesized on solid phase using the phosphoramidite building blocks 5-7. The hybridization properties of oligonucleotides were studied on duplexes with parallel and antiparallel chain orientation. It was found that the 7-halogenated nucleoside analogues 3 and 4 enhance the duplex stability significantly in both parallel (ps) and antiparallel (aps) DNA. Moreover, the halogenated nucleosides shift the tautomeric keto-enol equilibrium strongly toward the keto form, with K-TAUT [keto]/[enol] approximate to 10(4) coming close to that of 2'-deoxyguanosine (10(4)-10(5)), while the nonhalogenated 7-deaza-2'deoxyisoguanosine 2 shows a KTAUT of around 2000 and the enol concentration of 1 is 10 % in aqueous solution. Consequently, nucleosides 3 and 4 show a much better mismatch discrimination against dT than compound 1 or 2 in antiparallel as well as in parallel DNA. 3 and 4 are expected to increase the selectivity of base incorporation opposite to isoC(d) in the form of triphosphates or in the polymerase-catalyzed reaction in comparison to 1 or 2.
ISSN: 00027863
DOI: 10.1021/ja0425785

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