title: Excitation energy transfer in DNA: duplex melting and transfer from normal bases to 2-aminopurine.
abstract: Absorption and fluorescence excitation and emission spectra of the B DNA duplex decamer d[CTGA(2AP)TTCAG]2, where emission from the 2AP (2-aminopurine) base dominates, have been measured as a function of temperature. A low-temperature excitation band in the 260-270-nm region disappears near the duplex melting temperature, Tm = 27 degrees C, but then reappears at higher temperatures. Singlet-singlet energy transfer thus occurs between the normal DNA bases and the 2AP base in the B-helical conformation and to a lesser extent in the structurally-mobile melted conformation. The measured efficiency of transfer is 4-5% at 4 degrees C, near 0 at 30 degrees C, and rises again to 1% at 48 degrees C. Nearest-neighbor-only singlet transfer is likely. Such transfer does not offer a likely explanation for UV damage distributions in DNA.
authors.affiliation: Department of Physics, University of Alabama at Birmingham 35294-1170.
authors.forename: T M
authors.initials: TM
authors.lastname: Nordlund
authors.forename: D
authors.initials: D
authors.lastname: Xu
authors.forename: K O
authors.initials: KO
authors.lastname: Evans
mesh_terms: D015075:2-Aminopurine / Q000737:chemistry*; D001483:Base Sequence; D004247:DNA / Q000737:chemistry*; D008969:Molecular Sequence Data; D009691:Nucleic Acid Denaturation; D009838:Oligodeoxyribonucleotides; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature; D013816:Thermodynamics
chemical_list: D009838:Oligodeoxyribonucleotides; D015075:2-Aminopurine; D004247:DNA