PURIFICATION AND PROPERTIES OF NITROALKANE-OXIDIZING ENZYME FROM HANSENULA-MRAKII

A nitroalkane-oxidizing enzyme was purified about 1300-fold from a cell extract of H. mrakii grown in a medium containing nitroethane as the sole N source by ammonium sulfate fractionation, diethylaminoethylcellulose column chromatography, hydroxyapatite column chromatography and Bio-Gel P-150 column chromatography. The enzyme was homogeneous upon acrylamide gel electrophoresis and ultracentrifugation. The enzyme exhibited absorption maxima at 274, 370, 415 and 440 nm and a shoulder at 470 nm. Balance studies showed that 2 mol of 2-nitropropane was converted into an equimolar amount of acetone and nitrite with the consumption of 1 mol of oxygen. H2O2 was not formed in the enzyme reaction. In addition to 2-nitropropane, 1-nitropropane and nitroethane were oxidatively denitrified by the enzyme, but nitromethane was inert to the enzyme. The nitroalkanes were not oxidized under anaerobic conditions.