Base-pair induced shifts in the tautomeric equilibrium of a modified DNA base.
J Mol Biol
; 230(1): 6-10, 1993 Mar 05.
Article
em En
| MEDLINE
| ID: mdl-8450552
ABSTRACT
We have examined the base-pairing properties of N4-methoxycytosine (mo4C), a mutagenic base analog, in DNA by nuclear magnetic resonance spectroscopy. Unlike standard bases, the tautomeric equilibrium of mo4C could be strongly influenced by base-pair formation. Paired with A, mo4C is found predominantly in the imino configuration in Watson-Crick geometry. However, when paired with G, two structurally distinct configurations are observed in equilibrium with one another. In one configuration, mo4C is in the amino form paired with G in Watson-Crick geometry. In the second species, mo4C is in the imino configuration paired with G in a wobble geometry. This is the first demonstration of basepair induced tautomeric shifts in DNA and supports the hypothesis that rare tautomeric forms may be involved in mutagenesis.
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En
Ano de publicação:
1993
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Article