Conversion of glutathione to glutathione disulfide by cell membrane-bound oxidase activity.

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Abstract
An apparently specific glutathione oxidase activity is present in [rat] renal cortex, epididymal caput, jejunal villus tip cells, choroid plexus and retina, but is not present in liver. The activity is membrane-bound and is localized on the luminal surface of the brush border membranes of the kidney and jejunum. The distribution and localization of the oxidase are similar to those of .gamma.-glutamyl transpeptidase, there may be a significant relationship among the translocation of intracellular glutathione, the extracellular oxidation of glutathione to glutathione disulfide and the reactions of the .gamma.-glutamyl cycle. Glutathione present in the blood plasma and intracellular glutathione translocated to the cell surface are accessible to oxidation and transpeptidation. Acceptor substrates of the transpeptidase (e.g., L amino acids) promote transpeptidation and decrease oxidation of glutathione. Conversion of glutathione to glutathione disulfide is followed by utilization of the latter compound by .gamma.-glutamyl transpeptidase and dipeptidase. Intracellular oxidation of glutathione to glutathione disulfide is readily reversed by the action of glutathione reductase, but glutathione disulfide formed extracellularly cannot be reduced; instead, it undergoes hydrolytic and transpeptidation reactions leading to .gamma.-glutamyl amino acid and amino acid products which may be recovered by being transported into the cell.