PURIFICATION AND CHARACTERIZATION OF NADPH-DEPENDENT 2-OXOALDEHYDE REDUCTASE FROM CHICKEN LIVER

The enzymes which metabolize 2-oxoaldehyde compounds in a crude extract of chicken liver were examined using 3-deoxyglucosone (3-DG) and methylglyoxal (MG). NADH- and NADPH-dependent reductase activities were observed and the latter was more than the former. NADPH-dependent 2-oxoaldehyde reductase was purified from chicken liver by ammonium sulfate fractionation, and DEAE-cellulose, CM-cellulose, hydroxylapatite, and Sephadex G-100 column chromatographies. The molecular weight of the enzyme was estimated to be 38,00, and 32,000 by SDS-PAGE and gel filtration, respectively. The optimum pH was 6.5-7.0 and this enzyme was stable at pH 7.0-8.0. The Km for 3-DG and MG were 3.75 mM and 1.52 mM, respectively. This enzyme had high activities towards 2-oxoaldehyde compounds, such as 3-DG, MG, and phenylglyoxal. This enzyme converted 3-deoxyglucosone (3-DG) to 3-deoxyfructose, and methylglyoxal (MG) to acetol.