Glyoxalase III from Escherichia coli: a single novel enzyme for the conversion of methylglyoxal into D-lactate without reduced glutathione

• Published in: Biochemical journal Vol. 305 ( Pt 3); no. 3; pp. 999 - 1003
• Main Authors: Misra, K, Banerjee, A B, Ray, S, Ray, M
• Format: Journal Article
• Language: English
• Published: England 01.02.1995
• Subjects: Aldehyde Oxidoreductases - antagonists & inhibitors; Aldehyde Oxidoreductases - chemistry; Aldehyde Oxidoreductases - metabolism; Dithiothreitol - pharmacology; Escherichia coli - enzymology; Escherichia coli - growth & development; Glutathione - metabolism; Hydrogen-Ion Concentration; Hydroxymercuribenzoates - pharmacology; Lactates - metabolism; Lactic Acid; Molecular Weight; Oxidation-Reduction; Phenylglyoxal - metabolism; Pyruvaldehyde - metabolism; Substrate Specificity; Sulfhydryl Compounds - analysis; Sulfhydryl Compounds - metabolism
• ISSN: 0264-6021; 1470-8728
• DOI: 10.1042/bj3050999

A single novel enzyme, glyoxalase III, which catalyses the conversion of methylglyoxal into D-lactate without involvement of GSH, has been detected in and purified from Escherichia coli. Of several carbonyl compounds tested, only the alpha-ketoaldehydes methylglyoxal and phenylglyoxal were found to be substrates for this enzyme. Glyoxalase III is active over a wide range of pH with no sharp pH optimum. In its native form it has an M(r) of 82000 +/- 2000, and it is composed of two subunits of equal M(r). Glutathione analogues, which are inhibitors of glyoxalase I, do not inhibit glyoxalase III. Glyoxalase III is found to be sensitive to thiol-blocking reagents. The p-hydroxymercuribenzoate-inactivated enzyme could be almost completely re-activated by dithiothreitol and other thiol-group-containing compounds, indicating the possible involvement of thiol group(s) at or near the active site of the enzyme.