期刊
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
卷 7, 期 6, 页码 950-954出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.jpclett.6b00074
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资金
- NSF [CHE-1112560]
- M. J. Murdock Charitable Trust
- Italian Ministero dell'Istruzione, dell'Universita e della Ricerca (MIUR) [PRIN-2010ERFKXL]
- French Agency for Research Grant [ANR-12-BS08-0001-01]
- LR Campania [5/2002]
- Direct For Mathematical & Physical Scien
- Division Of Chemistry [1465277] Funding Source: National Science Foundation
- Direct For Mathematical & Physical Scien
- Division Of Chemistry [1112560] Funding Source: National Science Foundation
The excited-state dynamics of three distinct forms of the d(GC)(9)center dot d(GC)(9) DNA duplex were studied by combined time-resolved infrared experiments and quantum mechanical calculations. In the B- and Z-forms, bases on opposite strands form Watson-Crick (WC) base pairs but stack differently because of salt-induced changes in backbone conformation. At low pH, the two strands associate by Hoogsteen (HG) base pairing. Ultraviolet-induced intrastrand electron transfer (ET) triggers interstrand proton transfer (PT) in the B- and Z-forms, but the PT pathway is blocked in the HG duplex. Despite the different decay mechanisms, a common excited-state lifetime of similar to 30 ps is observed in all three duplex forms. The ET-PT pathway in the WC duplexes and the solely intrastrand ET pathway in the HG duplex yield the same pair of pi-stacked radicals on one strand. Back ET between these radicals is proposed to be the rate-limiting step behind excited-state deactivation in all three duplexes.
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