title: Watson-Crick base pairing controls excited-state decay in natural DNA.
abstract: Excited-state dynamics are essential to understanding the formation of DNA lesions induced by UV light. By using femtosecond IR spectroscopy, it was possible to determine the lifetimes of the excited states of all four bases in the double-stranded environment of natural DNA. After UV excitation of the DNA duplex, we detected a concerted decay of base pairs connected by Watson-Crick hydrogen bonds. A comparison of single- and double-stranded DNA showed that the reactive charge-transfer states formed in the single strands are suppressed by base pairing in the duplex. The strong influence of the Watson-Crick hydrogen bonds indicates that proton transfer opens an efficient decay path in the duplex that prohibits the formation or reduces the lifetime of reactive charge-transfer states.
authors.affiliation: BioMolecular Optics and Center for Integrated Protein Science (CIPSM), Ludwig-Maximilians-Universität München, Oettingenstrasse 67, 80538 Munich (Germany); Center for Integrated Protein Science at the Department of Chemistry, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, 81377 Munich (Germany).
authors.forename: Dominik B
authors.initials: DB
authors.lastname: Bucher
authors.forename: Alexander
authors.initials: A
authors.lastname: Schlueter
authors.forename: Thomas
authors.initials: T
authors.lastname: Carell
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Zinth
mesh_terms: D000818:Animals; D020029:Base Pairing / Q000528:radiation effects*; D002417:Cattle; D004247:DNA / Q000737:chemistry*; D008958:Models, Molecular; D009690:Nucleic Acid Conformation / Q000528:radiation effects; D055668:Photochemical Processes; D013055:Spectrophotometry, Infrared; D014466:Ultraviolet Rays
chemical_list: D004247:DNA; C427203:calf thymus DNA
keywords: DNA photochemistry; base pairing; excited-state decay; femtosecond IR spectroscopy; proton transfer