Metabolism of S-Sulfocysteine in Salmonella typhimurium. Role of Thioredoxin in the Reduction of S-Sulfocysteine

Abstract

The metabolism of S-sulfocysteine was studied in Salmonella typhimurium. Nutritional experiments with sulfite- and sulfide-requiring mutants ascertained that this amino acid is converted into cysteine and sulfite, and served exclusively as a sulfur source. Two different NADPHdepending systems able to participate in the metabolism of S-sulfocysteine were detected in a crude extract. Both systems were purified and identified as glutathione-glutathione reductase and thioredosin-thioredoxin reductase. The latter system seems to function more efficiently.