<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Kaloudis, P</style></author><author><style face="normal" font="default" size="100%">D'Angelantonio, M</style></author><author><style face="normal" font="default" size="100%">Guerra, M</style></author><author><style face="normal" font="default" size="100%">Gimisis, T.</style></author><author><style face="normal" font="default" size="100%">Mulazzani, Q G</style></author><author><style face="normal" font="default" size="100%">Chatgilialoglu, C</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">{One-electron reduction of 8-bromo-2-aminoadenosine in the aqueous phase: Radiation chemical and DFT studies of the mechanism}</style></title><secondary-title><style face="normal" font="default" size="100%">J. Phys. Chem. B</style></secondary-title></titles><dates><year><style  face="normal" font="default" size="100%">2008</style></year></dates><number><style face="normal" font="default" size="100%">16</style></number><volume><style face="normal" font="default" size="100%">112</style></volume><pages><style face="normal" font="default" size="100%">5209–5217</style></pages><isbn><style face="normal" font="default" size="100%">1520-6106</style></isbn><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Two tautomeric forms of one-electron oxidized 2-aminoadenosine (2AA) have been produced by reactions of hydrated electrons (e(aq)(-)) with 8-bromo-2-aminoadenosine (8-Br-2AA) at natural pH, whereas only one tautomer is formed by oxidation of 2AA. Tailored experiments by pulse radiolysis and time-dependent DFT (TD-B3LYP/6-311G**//B1B95/6-31+G**) calculations allowed the definition of the reaction mechanism in some detail. The electron adducts of 8-Br-2AA protonated at C8 eject Br- and produce the two short-lived tautomers (8 and 9). The first observable species decays by first-order kinetics to produce the second intermediate, which is also obtained by oxidation of 2AA by SO4 center dot-. The rate of tautomerization (k(taut) = 4.5 x 10(4) s(-1)) is strongly accelerated by phosphate and is retarded in D2O (kinetic isotope effect 7). B1B95/631+G** calculations showed that the tautomerization is a water-assisted process. In acidic or basic solutions, the &quot;instantaneous&quot; formation of one-electron oxidized 2AA or its deprotonated forms has been produced by reactions of e(aq)(-) with 8-Br-2AA. gamma-Radiolysis of 8-Br-2AA in aqueous solutions followed by product studies led to the formation of 2AA as a single product.</style></abstract></record></records></xml>