Function
Catalyzes the conversion of hemimercaptal, formed from methylglyoxal and glutathione, to S-lactoylglutathione. Active toward the hemithioacetal adducts formed by reacting methylglyoxal or phenylglyoxal with glutathione, homoglutathione or gamma-glutamylcysteine, showing no preference for homoglutathione adducts over glutathione adducts.