Properties of new enzyme glycerol oxidase from Aspergillus japonicus AT 008.

Abstract

Purified glycerol oxidase from Aspergillus japonicus AT 008 was homogeneous by ultracentrifugation and acrylamide gel electrophoresis. The molecular weight was determined to be 400,000 by sedimentation equilibrium, and the isoelectric point was found to be 4.9 by isoelectric focusing. The enzyme showed spectral characteristics of a heme protein. The reduced form possessed absorption maxima at 557 and 430 nm and the oxidized one at 557, 530, 420, 280, and 238 nm. The heme in the enzyme was identified as protoheme IX (one mol per mol of enzyme protein).Glycerol was the best substrate for the enzyme, and the Km value for glycerol was determined to be 10.4 mm. Dihydroxyacetone was oxidized at 59% of that for glycerol, but glycerol 3-phosphate, dihydroxyacetone phosphate, methanol, and ethanol were not oxidized at all. The enzyme had an optimal pH at 7.0 with glycerol as substrate, and the enzymatic activity increased by treatment in alkaline pH. The enzyme was also activated by addition of several divalent me...