Thiolesterase that catalyzes the hydrolysis of S-D-lactoyl-glutathione to form glutathione and D-lactic acid. an S-(2-hydroxyacyl)glutathione + H2O = a 2-hydroxy carboxylate + glutathione + H(+) Binds 1 Fe(2+) or Fe(3+) and 1 Zn(2+) ion per subunit. Electron spin resonance indicates the presence of a mixture of protein molecules that contain either Fe(2+) or Zn(2+). Secondary metabolite metabolism; methylglyoxal degradation; (R)-lactate from methylglyoxal: step 2/2. A number of isoforms are produced. According to EST sequences. Mainly expressed in roots, flowers and flower buds. Also detected in leaves. Belongs to the metallo-beta-lactamase superfamily. Glyoxalase II family.