Direct spectroelectrochemical titration of glutathione

Previous potentiometric attempts to determine the formal potential (E-0') of key intracellular redox buffer glutathione resulted in contradictory values. We have developed a spectroelectrochemical method using direct reduction on metal oxide electrodes. Disulfide absorbance at 258 nm was used to titrate glutathione in the thin layer cell reversibly. At conditions close to physiological ([GSH] = 0.001-0.005 mol/l, pH = 7.34; I = 0.1 mol/l; T = 298.15 K), we have measured glutathione E-0' = -0.22 +/- 0.02 V (NHE), corroborating the results of equilibrium measurements. Published by Elsevier B.V.