| Base-selective oxidation and cleavage of DNA by photochemical cosensitized electron transfer. | |
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MedLine Citation:
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PMID: 1445897 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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A photochemical mechanism for single-strand cleavage of DNA is proposed in which a photoexcited intercalator transfers an electron to an externally bound cosensitizer. Once formed, the oxidized intercalator oxidizes an adjacent base, creating a charge-separated complex from which reactions leading to cleavage of the sugar-phosphate backbone occur in competition with back electron transfer. Using ethidium bromide (EB) as the intercalator and methyl viologen (MV) as the externally bound cosensitizer, a 10-fold enhancement in the rate of single-strand break formation was found in pBR322 DNA over that for EB alone using 488-nm excitation. The rate of cleavage correlated with the amount of MV bound to DNA. In accord with the expected redox properties of the one-electron-oxidized EB and the DNA bases, cleavage occurs selectively at guanines. Although the reaction proceeds in nitrogen-purged solutions, the rate of cleavage in air-saturated solutions was enhanced 2-fold. Treatment of irradiated samples with alkali leads to a 2-fold increase in the yield of single-strand breaks. These results support a mechanism in which cleavage occurs by selective oxidation of guanines in DNA, initiated by photochemical cosensitized electron transfer from intercalated EB to externally bound MV, and may provide a basis for the development of light-activated base-selective DNA cleaving agents. |
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Authors:
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D A Dunn; V H Lin; I E Kochevar |
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Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Biochemistry Volume: 31 ISSN: 0006-2960 ISO Abbreviation: Biochemistry Publication Date: 1992 Nov |
Date Detail:
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Created Date: 1992-12-30 Completed Date: 1992-12-30 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 0370623 Medline TA: Biochemistry Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 11620-5 Citation Subset: IM |
Affiliation:
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Department of Dermatology, Massachusetts General Hospital, Harvard Medical School, Boston 02114. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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DNA
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drug effects* Electron Transport Electrophoresis, Polyacrylamide Gel Ethidium / chemistry Intercalating Agents / chemistry Oxidation-Reduction Paraquat / chemistry Photochemistry |
| Grant Support | |
ID/Acronym/Agency:
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223-89-1003//PHS HHS |
| Chemical | |
Reg. No./Substance:
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0/Intercalating Agents; 3546-21-2/Ethidium; 4685-14-7/Paraquat; 9007-49-2/DNA |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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