NMR studies of exocyclic 1,N sup 2 -propanodeoxyguanosine adducts (X) opposite purines in DNA duplexes: Protonated X(syn)ter dot A(anti) pairing (acidic pH) and X(syn)ter dot G(anti) pairing (neutral pH) at the lesion site
- Columbia Univ., New York, NY (USA)
- State Univ. of New York, Stony Brook (USA)
Proton and phosphorus two-dimensional NMR studies are reported for the complementary d(C1-A2-T3-G4-X5-G6-T7-A8-C9){center dot}d(G10-T11-A12-C13-A14-C15-A16-T17-G18) nonanucleotide duplex (designated X{center dot}A 9-mer) that contains a 1,N{sup 2}-propanodeoxyguanosine exocyclic adduct, X5, opposite deoxyadenosine A14 in the center of the helix. The NMR studies detect a pH-dependent conformational transition; this paper focuses on the structure present at pH 5.8. The two-dimensional NOESY studies of the X{center dot}A 9-mer duplex in H{sub 2}O and D{sub 2}O solution establish that X5 adopts a syn orientation while A14 adopts an anti orientation about the glycosidic bond at the lesion site. At pH 5.8, the observed NOE between the H8 proton of X5 and the H2 proton of A14 in the X{center dot}A 9-mer duplex demonstrates unequivocally the formation of the protonated X5(syn){center dot}A14(anti) pair. A perturbation in the phosphodiester backbone is detected at the C13-A14 phosphorus located at the lesion site by {sup 31}P NMR spectroscopy. The two-dimensional NMR studies have been extended to the related complementary X{center dot}G 9-mer duplex that contains a central X5{center dot}G14 lesion in a sequence that is otherwise identical with the X{center dot}A 9-mer duplex. The NMR experimental parameters are consistent with formation of a pH-independent X5(syn){center dot}G14(anti) pair stabilized by two hydrogen bonds with the 1,N{sup 2}-propano exocyclic adduct of X5(syn) located in the major groove.
- OSTI ID:
- 5034797
- Journal Information:
- Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 28:13; ISSN 0006-2960; ISSN BICHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
62 RADIOLOGY AND NUCLEAR MEDICINE
ADDUCTS
BARYONS
DNA ADDUCTS
ELEMENTARY PARTICLES
FERMIONS
HADRONS
HEAVY WATER
HYDROGEN COMPOUNDS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEI
NUCLEONS
ODD-EVEN NUCLEI
OVERHAUSER EFFECT
OXYGEN COMPOUNDS
PH VALUE
PHOSPHORUS 31
PHOSPHORUS ISOTOPES
PROTONS
RESONANCE
SPECTRA
STABLE ISOTOPES
WATER