The SO4 ·̄induced Oxidation of 2′-Deoxyuridine-5′-phosphate, Uridine-5′-phosphate and Thymidine-5′-phosphate. An ESR Study in Aqueous Solution
Open Access
- 1 February 1990
- journal article
- research article
- Published by Walter de Gruyter GmbH in Zeitschrift für Naturforschung C
- Vol. 45 (1-2) , 47-58
- https://doi.org/10.1515/znc-1990-1-210
Abstract
Reactions of photolytically generated SO4- with 2''-deoxyuridine-5''-phosphate (5''-dUMP), uridine-5''-phosphate (5''-UMP) and thymidine-5''-phosphate (5''-dTMP) were studied by ESR spectroscopy in aqueous solution under anoxic conditions. From 5''-dUMP and 5''-UMP the 5'',5-cyclic phosphate-6-yl radicals 10 and 11 were generated (pH 2-11) whereas from 5''-dTMP at pH 3-8 the 5,6-dihydro-6-hydroxy-5-yl radical 14 and at pH 7-11 the 5-methylene-2''-deoxyuridine-5''-phosphate radical 15 was produced. In the experiments with 5''-UMP in addition to radical 11 the signals of sugar radicals 12 and 13 were detected. It is assumed that the base radical cations act as intermediates in the SO4--induced radical reactions. The 5''-phosphate group adds intramolecularly to the C(5)-C(6) bond of the uraclilyl radical cation whereas the thymidyl radical cation of 5''-dTMP reacts with H2O at pH < 8 to yield the 6-OH-5-yl adduct 14 and deprotonates at pH > 7 thus forming the allyl-type radical 15. In 5''-UMP transfer of the radical site from the base to the sugar moiety competes with intramolecular phosphate addition.Keywords
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