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

Cystine glutathione transhydrogenase, cystine-reductase, and glutathione 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 or biochemical characteristics of these enzymes between cells of cystinotic and normal subjects.