Berlin 2005 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 30: POSTER: Chemical physics
CPP 30.12: Poster
Dienstag, 8. März 2005, 16:30–18:30, Poster TU D
Short-lived radicals of purine bases in aqueous solution: reactivity and characterization by magnetic resonance — •Alexey Kiryutin1,2, Olga Morozova2, Alexandra Yurkovskaya2, and Hans-Martin Vieth1 — 1Department of Physics, Free University of Berlin, D-14195 Berlin, Germany — 2International Tomography Center of SB RAS, 630090, Institutskaya 3a, Novosibirsk, Russia
The structure of nucleic acids and the mobility of their bases can be probed by the effects of dynamic nuclear spin polarization (CIDNP) created in reversible photoreactions between individual bases and suitable organic dye molecules. For quantitative studies detailed information on the reactions of the dye with the basic building blocks is required. The quenching of triplet excited 2,2’-dipyridyl by the two purine nucleotides guanosine and adenosine monophosphate (GMP and AMP) and the subsequent radical pair decay is a prototype of such a reaction. Laser flash photolysis and CIDNP techniques were applied to get information on the quenching rates and the mechanism of this chemical process and on the structure of the radicals so formed as a function of the pH of aqueous solution. By time-resolved CIDNP the influence of the secondary process of degenerate electron exchange between AMP and its cation radical was studied. For GMP and AMP the CIDNP was measured at variable magnetic field (0..7 T). From simulation of these field dependencies the hyperfine couplings and g-factors of the short-lived neutral, anionic and cationic forms of the nucleoside radicals were determined.