Enzymic reduction of cystine and glutathione in cultivated human fibroblast from normal subjects and patients with cystinosis.

Cystine glutathione transhydrogenase, cystine-reductase, and glutathion reductase activities were studied in cultivated skin fibroblasts of control subjects and of three patients with cystinosis. Specific activity, pH optima, electrophoretic mobility, and kinetic parameters were described. Evidence for two isoenzyme forms of cystine-glutathione transhydrogenase was obtained. No difference was detected in activity of biochemical characteristics of these enzymes between cells of cystinotic and normal subjects.