Isolation, Purification, and Characterization of Lipase Isoenzymes from a Technical Aspergillus niger Enzyme

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Abstract
A qualitative screening revealed the occurrence of lipase, esterase, protease, amylase, endo‐1,4‐β‐D‐glucanase, xylanase, pectinmethylesterase, polygalacturonase, catalase, β‐D‐glucosidase and β‐D‐galactosidase activities in the technical Aspergillus niger enzyme under study (Lipase 2212 D, Röhm). The isolation and purification of lipolytic activities were performed by combination of DEAE‐Trisacryl M ion exchange chromatography, Sephadex G 50 gel filtration and hydrophobic chromatography using Phenylsepharose CL‐4B. The individual purification steps were checked by specific enzyme visualization in ultrathin agar gels after ultrathin‐layer isoelectric focusing (UIEF). Two UIEF homogeneous lipase isoenzymes (I and II) were isolated and characterized by the following parameters: isoelectric points (I: 4.0; II. 3.5); molecular weights (I: 31000 daltons; II: 19000 daltons); carbohydrate contents (I: 6%; II: 9%) and compositions; pH optima (I, II: 5‐6); substrate specificities and various effectors.