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Abstract:
Glyoxalase I (S-lactoyl-glutathione methylglyoxal-lyase (isomerizing), EC 4.4.1.5) was assayed using alcoholic, acidic 2,4-dinitrophenylhydrazine to follow the disappearance of methylglyoxal over time, with the absorbance of formed methylglyoxal bis-hydrazone measured at 432 nm. Erythrocyte glyoxalase I activities were found to be 64, 41, and 18 mumole of S-lactoyl glutathione formed min-1 X ml-1 of red blood cells in rat, human, and rabbit blood and 174 mumole X min-1 X mg-1 of protein for yeast. The Km values found in millimolar hemimercaptal were about 0.5. Glyoxalase I activity can be determined in crude tissue preparations without interference from biological materials.