Purification and characterization of a lipase from Aspergillus oryzae

A lipase from Aspergillus oryzae was purified by ammonium sulfate fractionation, anion exchange chromatography, hydrophobic interaction chromatography, and anion exchange chromatography. The purified enzyme was a monomeric protein with a molecular mass of 41 kDa estimated by SDS-PAGE and 39 kDa by gel filtration. The optimum pH at 30 degrees C and optimum temperature at pH 7.0 were 7.0 and 30 degrees C, respectively. The enzyme was stable over a pH range of 6-9 at 25 degrees C for 18 h, and up to 30 degrees C at pH 7.0 for 3 h. Ag+, Fe3+, Hg2+, Cu2+, and Zn2+ inhibited the enzyme activity severely. The enzyme was a lipase that hydrolyzed monoacylglycerols and diacylglycerols, but did not hydrolyze triacylglycerols. The N-terminal amino acid sequence of the enzyme was highly homologous with that of the mono- and diacylglycerol lipase from Penicillium camembertii U-150.