caa a22 4500 445321342 CHVBK 20180317142705.0 cr unu---uuuuu 170323e20111201xx s 000 0 eng 10.1007/s10534-011-9478-6 doi (NATIONALLICENCE)springer-10.1007/s10534-011-9478-6 Impact of uranium (U) on the cellular glutathione pool and resultant consequences for the redox status of U [Elektronische Daten] [Katrin Viehweger, Gerhard Geipel, Gert Bernhard] Uranium (U) as a redox-active heavy metal can cause various redox imbalances in plant cells. Measurements of the cellular glutathione/glutathione disulfide (GSH/GSSG) by HPLC after cellular U contact revealed an interference with this essential redox couple. The GSH content remained unaffected by 10μM U whereas the GSSG level immediately increased. In contrast, higher U concentrations (50μM) drastically raised both forms. Using the Nernst equation, it was possible to calculate the half-cell reduction potential of 2GSH/GSSG. In case of lower U contents the cellular redox environment shifted towards more oxidizing conditions whereas the opposite effect was obtained by higher U contents. This indicates that U contact causes a consumption of reduced redox equivalents. Artificial depletion of GSH by chlorodinitrobenzene and measuring the cellular reducing capacity by tetrazolium salt reduction underlined the strong requirement of reduced redox equivalents. An additional element of cellular U detoxification mechanisms is the complex formation between the heavy metal and carboxylic functionalities of GSH. Because two GSH molecules catalyze electron transfers each with one electron forming a dimer (GSSG) two UO2 2+ are reduced to each UO2 + by unbound redox sensitive sulfhydryl moieties. UO2 + subsequently disproportionates to UO2 2+ and U4+. This explains that in vitro experiments revealed a reduction to U(IV) of only around 33% of initial U(VI). Cellular U(IV) was transiently detected with the highest level after 2h of U contact. Hence, it can be proposed that these reducing processes are an important element of defense reactions induced by this heavy metal. Springer Science+Business Media, LLC., 2011 Uranium nationallicence GSH/GSSG nationallicence Half-cell reduction potential nationallicence Redox process nationallicence Complex formation nationallicence Viehweger Katrin Biogeochemistry Division, Institute of Radiochemistry, Helmholtz-Zentrum Dresden-Rossendorf eV, P.O. Box 510119, 01314, Dresden, Germany aut Geipel Gerhard Biogeochemistry Division, Institute of Radiochemistry, Helmholtz-Zentrum Dresden-Rossendorf eV, P.O. Box 510119, 01314, Dresden, Germany aut Bernhard Gert Biogeochemistry Division, Institute of Radiochemistry, Helmholtz-Zentrum Dresden-Rossendorf eV, P.O. Box 510119, 01314, Dresden, Germany aut BioMetals Springer Netherlands 24/6(2011-12-01), 1197-1204 0966-0844 24:6<1197 2011 24 10534 https://doi.org/10.1007/s10534-011-9478-6 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10534-011-9478-6 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Viehweger Katrin Biogeochemistry Division, Institute of Radiochemistry, Helmholtz-Zentrum Dresden-Rossendorf eV, P.O. Box 510119, 01314, Dresden, Germany aut NATIONALLICENCE 700 1- Geipel Gerhard Biogeochemistry Division, Institute of Radiochemistry, Helmholtz-Zentrum Dresden-Rossendorf eV, P.O. Box 510119, 01314, Dresden, Germany aut NATIONALLICENCE 700 1- Bernhard Gert Biogeochemistry Division, Institute of Radiochemistry, Helmholtz-Zentrum Dresden-Rossendorf eV, P.O. Box 510119, 01314, Dresden, Germany aut NATIONALLICENCE 773 0- BioMetals Springer Netherlands 24/6(2011-12-01), 1197-1204 0966-0844 24:6<1197 2011 24 10534 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer