S-(1,2-Dicarboxyethyl)glutathione in yeast: partial purification of its synthesizing enzyme

S-(1,2-Dicarboxyethyl)glutathione (DCE-GS) was found in Saccharomyces cerevisiae, but not in bacterial species nor in a unicellular alga (Acetabularia acetabulum). The enzyme that catalyzes condensation of L-malate and glutathione (GSH) to form DCE-GS was partially purified from baker's yeast. It had a molecular mass of 49 kDa and was monomeric and the Km values were 2.2 and 1.4 mM for L-malate and GSH, respectively. The enzyme had a pH optimum of 7.5. DCE-GS levels in yeast cells were significantly higher in aerobic cultures than in anaerobic ones. DCE-GS was synthesized in cells cultured between 20 and 35 degrees C.