The incorporation of isotopically labelled glycine into glutathione of erythrocytes with glucose-6-phosphate dehydrogenase deficiency

1. 1. Cysteine decreases the reduced glutathione level in normal red blood cells incubated under aerobic conditions in a glucose-free incubation medium. 2. 2. Cysteine has a similar effect in cells deficient in glucose-6-phosphate dehydrogenase, even in the presence of glucose. 3. 3. Investigations of the rate of glycine incorporation into glutathione of normal erythrocytes under aerobic conditions should be conducted in the presence of glucose when the incubation mixture contains cysteine. The glucose may be replaced by fructose, galactose or inosine. Cysteine should be omitted altogether from the incubation mixture when cells deficient in glucose-6-phosphate dehydrogenase are investigated. 4. 4. The rate of incorporation of glycine into glutathione in deficient cells was found to be lower than in normal cells. The possible causes of this difference are discussed.