Fe− and Co−Bleomycins Bound to Site Specific and Nonspecific DNA Decamers: Comparative Binding and Reactivity of Their Metal Centers
| Autor: | Chunqing Zhao, Eugene F. DeRose, William E. Antholine, Patricia Fulmer, D. H. Petering, Wenbao Li |
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| Rok vydání: | 1997 |
| Předmět: |
Magnetic Resonance Spectroscopy
Iron Inorganic chemistry Ascorbic Acid Cleavage (embryo) Biochemistry Oligomer Adduct Metal Bleomycin DNA Adducts chemistry.chemical_compound dnaB helicase Antibiotics Antineoplastic Molecular Structure Electron Spin Resonance Spectroscopy Cobalt DNA Nuclear magnetic resonance spectroscopy DnaA Peroxides Crystallography Spectrometry Fluorescence Oligodeoxyribonucleotides chemistry Spectrophotometry visual_art visual_art.visual_art_medium Nucleic Acid Conformation |
| Zdroj: | Biochemistry. 36:4367-4374 |
| ISSN: | 1520-4995 0006-2960 |
| DOI: | 10.1021/bi9625354 |
| Popis: | Co- and Fe-bleomycins (Blms) have been reacted with DNAa, d(GGAAGCTTCC)2, containing a specific site for cleavage, and DNAb, d(GGAAATTTCC)2, a closely related nonspecific 10-mer, to survey whether features of structure and reactivity of these adducts vary systematically as a function of the base sequence of the DNA oligomer. The ESR spectrum of NO-Fe(II)BlmDNAa is rhombically perturbed in comparison with that of NO-Fe(II)BlmDNAb, which is nearly identical to the spectrum of NO-Fe(II)Blm. The ESR spectrum of Fe(III)BlmDNAa in phosphate buffer is low-spin; that of Fe(III)BlmDNAb is high-spin as seen with Fe(III)Blm alone. According to absorbance spectroscopy, O2-Fe(II)BlmDNAa is stabilized in comparison with the DNAb adduct. Similar stabilization of O2-Co(II)Blm bound to DNAa but not to DNAb was also observed by ESR spectroscopy. HO2(-)-Co(III)Blm A2 binds in slow exchange on the NMR time scale to DNAa at its 5'-G-pyrimidine-3' site of cleavage. In contrast, fluorescence and NMR spectroscopy demonstrate that most of HO2(-)-Co(III)Blm A2 binds stoichiometrically in fast exchange to DNAb. The reactions of Fe(III)BlmDNAa and Fe(III)BlmDNAb with ascorbate and O2 reveal that the latter becomes activated and cleaves its 10-mer, producing base propenals, at a faster initial rate. Thus, in two series of metallobleomycins, (A) NO-Fe(II)Blm, O2-Fe(II)Blm, Fe(III)Blm in phosphate buffer, and HO2(-)-Fe(III)Blm and (B) O2-Co(II)Blm and HO2(-)-Co(III)Blm, the metal domain of each species interacts differently with DNA depending upon its base sequence. |
| Databáze: | OpenAIRE |
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