KINETICS AND MECHANISM OF THE OXIDATION OF GLUTATHIONE BY HEXACYANOFERRATE(III) IN AQUEOUS-SOLUTION

A detailed kinetic study of the oxidation of glutathione by Fe(CN)(6)(3-) was performed as a function of pH, temperature, and pressure. The pH profile indicates a maximum pH independent rate in the pH range 5 to 8, which is ascribed to the oxidation of the monoanionic form of glutathione. The activation parameters for the oxidation process in this pH range are characterized by significantly negative Delta V# (-22 cm(3) mol(-1)) values. The latter value is in good agreement with that calculated theoretically on the basis of the Marcus-Hush-Stranks relationships, and can be ascribed to a large volume collapse associated with the outer-sphere reduction of Fe(CN)(6)(3-) to Fe(CN)(6)(4-).