The reduction of chromium (VI) to chromium (III) by glutathione: An intracellular redox pathway in the metabolism of the carcinogen chromate

摘要: The capacity of glutathione (GSH) to reduce Cr(VI) Cr(III) in vitro was investigated. reaction determined spectrophotometrically by following the absorption Cr(VI0 at 370 nm. At stoichiometric conditions (molar ratio Cr(VI)/GSH 1:3) reduction strongly dependent on solution's pH. It much slower pH 7.4 than values below 5. An excess GSH (100- or 1000-fold) accelerated reaction. In any case, 3 molecules were required 1 molecule chromate. Incubation human red blood cells (RBC) with an Na2CrO4 (10 mM) decreased content 10% original amount. This depletion similar that obtained when RBC incubated 62 mM diethylmaleate (DEM), a well known depleting agent. Sephadex G-100 chromatography lysates from radioactive chromate (51Cr(VI)) showed strong affinity 51Cr for hemoglobin: 97% applied dose bound hemoglobin whilst only minor amounts found low-molecular fractions. However, incubations prepared (as opposed intact cells) 10 Na251CrO4 markedly raised chromium fractions (probably GSH-Cr-complexes), probably indicative role intra-cellular Cr(III), latter being regarded as ultimately toxic species this metal.