Analysis of glyoxalase-I from normal and tumor tissue

Abstract Glyoxalase-I (Gly-I) is part of the glyoxalase system which converts methylglyoxal to d -lactic acid via an S- d -lactoyglutathione intermediate. This glutathione (GSH)-binding protein was purified from human colon tumors and corresponding normal tissue. The GSH-affinity purified from normal human colon tissue showed enzyme activity of 30.6±11.5 μ mol/min per mg protein, with methylglyoxal as substrate. Corresponding fractions from carcinomas showed significantly elevated Gly-I activity of 54±15 μ mol/min per mg protein. Polyclonal antibodies made against human Gly-I cross-reacted weakly with mouse liver Gly-I but not with yeast Gly-I. Isoelectric points of Gly-I from human, mouse and yeast were determined to be 4.6, 4.9 and 7.0, respectively, by horizontal IEF. Immunohistochemical analysis confirmed the increase of Gly-I in human colon carcinoma in 16 out of 21 samples when compared to corresponding normal tissue. The elevated levels of Gly-I colon tumors may be an indicator of the enhanced proliferative status of the neoplastic condition.