NMR and computational characterization of mitomycin cross-linked to adjacent deoxyguanosines in the minor groove of the d(T-A-C-G-T-A)ter dot d(T-A-C-G-T-A) duplex
- Columbia Univ., New York, NY (USA)
- Emory Univ., Atlanta, GA (USA)
- City Univ. of New York, NY (USA)
- Oak Ridge National Lab., TN (USA)
- New York Univ., NY (USA)
Two-dimensional homonuclear and heteronuclear NMR and minimized potential energy calculations have been combined to define the structure of the antitumor agent mitomycin C (MC) cross-linked to deoxyguanosines on adjacent base pairs in the d(T1-A2-C3-G4-T5-A6){center dot}d(T7-A8-C9-G10-T11-A12) duplex. The majority of the mitomycin and nucleic acid protons in the MC-X 6-mer complex have been assigned from through-bond and through-space two-dimensional proton NMR studies in aqueous solution at 5 and 20{degree}C. The C3{center dot}G10 and G4{center dot}C9 base pairs are intact at the cross-link site and stack on each other in the complex. The amino protons of G4 and G10 resonate at 9.36 and 8.87 ppm and exhibit slow exchange with solvent H{sub 2}O. The NMR experimental data establish that the mitomycin is cross-linked to the DNA through the amino groups of G4 and G10 and is positioned in the minor groove. The proton chemical shifts and NOEs establish fraying at the ends of the d(T-A-C-G-T-A) duplex, and this feature is retained on mitomycin cross-linked formation. The NMR distance constraints have been included in minimized potential energy computations on the MC-X 6-mer complex. These computations were undertaken with the nonplanar five-membered ring of mitomycin in each of two pucker orientation. The resulting low-energy structures MX1 and MX2 have the mitomycin cross-linked in a widened minor groove with the chromophore ring system in the vicinity of the G10-T11 step on one of the two strands in the duplex. The experimental evidence supports this model since the H1{prime} of G10 is shifted dramatically upfield and the H1{prime} proton of T11 is shifted dramatically downfield on complex formation.
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 6322611
- Journal Information:
- Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 29:11; ISSN 0006-2960; ISSN BICHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
62 RADIOLOGY AND NUCLEAR MEDICINE
ADDUCTS
ALKYLATION
ANTI-INFECTIVE AGENTS
ANTIBIOTICS
ANTIMITOTIC DRUGS
ANTINEOPLASTIC DRUGS
BARYONS
CHEMICAL REACTIONS
CHEMICAL SHIFT
CROSS-LINKING
DNA
DNA ADDUCTS
DRUGS
ELEMENTARY PARTICLES
FERMIONS
HADRONS
MAGNETIC RESONANCE
MITOMYCIN
MOLECULAR STRUCTURE
NUCLEAR MAGNETIC RESONANCE
NUCLEIC ACIDS
NUCLEONS
ORGANIC COMPOUNDS
OVERHAUSER EFFECT
POLYMERIZATION
PROTONS
RESONANCE