KINETICS AND SPECTRAL PROPERTIES OF ELECTRON ADDUCTS OF 2'-DEOXYINOSINE - A COMPARISON WITH OTHER PURINE NUCLEOSIDES

The heteroatom-protonated electron adducts of 2'-deoxyinosine formed f ollowing rapid protonation of the initially-produced radical anions in neutral solution exhibit a broad peak around 310 mm, In neutral solut ions, these radicals transform spontaneously, in a slow process (k sim ilar to 2 x 10(4) s(-1)), into C-protonated adducts. This reaction is catalysed by OH- and the absorption changes at 350 nm vs. pH consist o f two types of pK(a) curve. The transformation rates in 2-deoxyinosine are somewhat higher than those found for inosine and are in accord wi th the yields of MV(+). The spectrum at pH greater than or equal to 13 .5 closely resembles the H-adduct spectrum recorded at neutral pH. Thi s spectrum with epsilon(315) = 5900 and epsilon(350) = 4400 dm(3) mol( -1) cm(-1) is assigned to the C-8 protonated adducts, This study sugge sts that the heteroatom-protonated and C-2 protonated electron adducts of 2'-deoxyinosine are probably less stable than the corresponding ra dicals of inosine.