Purification and Biochemical Characterization of a Lipase Produced by Aspergillus Niger: Interfacial Binding, Activity of Lipase at the Lipid-Water Interface Using Monomolecular Film Techniques

Abstract

Aspergillus Niger lipase (ANL) was purified from a culture medium. Pure ANL was obtained after ammonium sulfate fractionation, Sephacryl S-200 gel filtration and cation exchange chromatography (Mono-Q). The pure lipase, which is not a glycoprotein, was presented as a monomer having a molecular mass of about 99 kDa. The lipase activity was maximal at pH 8 and at 39°C. ANL hydrolyses the long chains of triacylglycerols more efficiently than the short ones. A specific activity of 3779 U/mg was measured on olive oil as substrate at 39°C and at pH 8 in the presence of 4 mM NaTDC. ANL was inactivated when the enzyme was incubated at 75°C or at pH less than 4. Natural detergent (NaTDC), pH dependence of the catalytic activity of ANL was at pH 8, which confirm that ANL present one pH profile.