Purification and characterization of lipase from rice (<i>Oryza sativa</i> L.) bran

Abstract

Abstract Lipase from defatted rice bran has been isolated by a new procedure which yields higher enzyme activity and quantity of enzyme. The procedure involves selective ammonium sulphate precipitation followed by ion exchange chromatography using DEAE‐Sepharose CL‐6B gel and column chromatography. The purified and homogeneous enzyme is also characterized for its various optical, enzymatic, physico‐chemical and hydrodynamic properties. The enzyme has an ultraviolet absorption maximum at 276 nm with an extinction coefficient value of 15.25. The fluorescence excitation and emission maximum values for the enzyme are 285 and 344 nm, respectively. The enzyme has a specific activity of 18 units [μeq · mg −1 · h −1 ] with a pH optimum of 7.5 and a temperature optimum of 30 °C. The enzyme has an average hydrophobicity value of 3980 J/residue and the NPS (frequency of occurrance of non‐polar side chains) and P (ratio of polar to non‐polar amino acids) values are 0.29 and 1.13, respectively. The enzyme has a sedimentation coefficient value of 2.30 S and the isopotential partial specific volume is 0.697 ml/g. The molecular weight of the enzyme is 30000 and the enzyme is made up of at least two subunits. The enzyme contains 16% alpha‐helix, 39% beta‐structure and the rest being aperiodic.