Glyoxalase I is a ubiquitous enzyme that detoxifies methylglyoxal, which is derived from glycolysis but inhibits the growth of cells from microorganisms to mammals. Here, the structural gene for glyoxalase I ( glo1(+)) from the fission yeast Schizosaccharomyces pombe was identified. Disruption of glo1(+) enhanced susceptibility to methylglyoxal, while expression of glo1(+) in a Delta glo1 mutant of Saccharomyces cerevisiae restored tolerance to this aldehyde. The glo1(+) gene product was purified. The glyoxalase I of S. pombe was a monomeric enzyme with a molecular weight of 34000 and the k(cat)/ K(m) value for methylglyoxal was 4.3 x 10(7) M(-1) x min(-1). Treatment of purified enzyme with EDTA in imidazole buffer completely abolished enzyme activity, whereas the EDTA-treated enzyme was reactivated by several divalent metal ions, such as Zn(2+), Co(2+), Ni(2+) and Mn(2+). The glyoxalase I of S. pombe exhibited fairly high thermal stability, and almost 100% activity was retained after incubating the enzyme at 60 degrees C for 4 h.