Sequence dependence of energy transfer in DNA oligonucleotides.
The sequence, temperature, concentration, and solvent dependence of singlet energy transfer from normal DNA bases to the 2-aminopurine base in synthesized DNA oligomers were investigated by optical spectroscopy. Transfer was shown directly by a variable fluorescence excitation band at 260-280 nm. Adenine (A) is the most efficient energy donor by an order of magnitude. Stacks of A adjacent to 2AP act as an antenna for 2AP excitation. An interposed G, C, or T base between A and 2AP effectively blocks transfer from A to 2AP. Base stacking facilitates transfer, while base pairing reduces energy transfer slightly. The efficiency is differentially temperature dependent in single- and double-stranded oligomers and is highest below 0 degrees C in samples measured. An efficiency transition occurs well below the melting transition of a double-stranded decamer. The transfer efficiency in the duplex decamer d(CTGA[2AP]TTCAG)(2) is moderately dependent on the sample and salt concentration and is solvent dependent. Transfer at physiological temperature over more than a few bases is improbable, except along consecutive A's, indicating that singlet energy transfer is not a major factor in the localization of UV damage in DNA. These results have features in common with recently observed electron transfer from 2AP to G in oligonucleotides.
Xu
D G
DG
Department of Physics, University of Alabama at Birmingham, Birmingham, Alabama 35294-1170, USA.
Nordlund
T M
TM
D015075:2-Aminopurine / Q000737:chemistry; D020029:Base Pairing; D004247:DNA / Q000737:chemistry*; D004583:Electrons; D004735:Energy Transfer; D008962:Models, Theoretical; D009690:Nucleic Acid Conformation; D009691:Nucleic Acid Denaturation; D009841:Oligonucleotides / Q000737:chemistry*; D012492:Salts / Q000494:pharmacology; D012997:Solvents; D013050:Spectrometry, Fluorescence; D013696:Temperature
D009841:Oligonucleotides; D012492:Salts; D012997:Solvents; D015075:2-Aminopurine; D004247:DNA