Type II glyoxalase, isozyme of GloB, that hydrolyzes (R)-S-lactoylglutathione to (R)-lactate and glutathione. Plays a minor contribution to methylglyoxal (MG) detoxification in E.coli, compared to GloB. The two isoenzymes have additive effects and ensure maximal MG degradation. an S-(2-hydroxyacyl)glutathione + H2O = a 2-hydroxy carboxylate + glutathione + H(+) (R)-S-lactoylglutathione + H2O = (R)-lactate + glutathione + H(+) Binds 2 Zn(2+) ions per subunit. Is inhibited by Cu(2+). kcat is 0.9 sec(-1) for the hydrolysis of (R)-S-lactoylglutathione. Secondary metabolite metabolism; methylglyoxal degradation; (R)-lactate from methylglyoxal: step 2/2. Cells lacking this gene show decreased methylglyoxal tolerance. A double deletion mutant lacking both gloC and gloB exhibits almost no resistance to exogenously supplied methylglyoxal, and is unable to grow at MG concentrations as low as 0.1 mM. Belongs to the metallo-beta-lactamase superfamily. Glyoxalase II family.