Purification and characterization of lipase from rice (Oryza sativa L.) bran

Abstract

SummaryLipase 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 cmission maximum values for the enzyme are 285 and 344 nm, respectively. The enzyme has a specific activity of 18 units [peq . mg-' . 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. Zusammenfassung Reinigung und Charakterisierung von Lipase aus Reiskleie

Rice Bran Lipase: Extraction, Activity, and Stability

“…Maximum activity of the lipase enzyme was observed at pH 7–7.5 (Figure 1). These results are in agreement with those reported by Shastry and Rao (18) and Rajeshwar and Prakash (27) for the optimum pH of the lipase. Hence, potassium phosphate buffer of pH 7 was used for the extraction of lipase in all further experiments.…”

“…However, at higher temperatures, the activity diminished, indicating the thermolability of the lipase preparation. Rajeshwar and Prakash (27) also obtained activity maxima for triacetin hydrolysis using IR‐20 rice bran lipase at 30 °C, and on either side of that temperature, they obtained a sharp decline in activity. Thus, they obtained a bell‐shaped curve for the temperature dependence of lipase activity.…”

“…Most of the work published on this enzyme deals with its deactivation to stabilize the bran for its subsequent oil extraction (24, 25). Other studies on rice bran lipase deal with the elucidation of its structural and biochemical properties (18, 23, 26, 27). No efforts have been reported to explore the possibility of extraction of lipase from rice bran for commercial use, a result of either the poor yield of the enzyme or the lack of information on the enzyme content of the different varieties of rice.…”

Mechanism of Inhibition of Rice Bran Lipase by Polyphenols: A Case Study with Chlorogenic Acid and Caffeic Acid

“…The enzyme RBL differing in their molecular weights was previously isolated (both isoforms Lipase I and II) and well characterized in terms of physicochemical properties (Funatsu and others 1971; Aizono and others 1976; Shastry and Raghavendra Rao 1976). RBL used in this study contains 274 amino acids with molecular weight of 30 kD (Rajeshwara and Prakash 1995). Of course, the technique used in determining the molecular weight of a protein determines the accuracy of the molecular weight such as sodium dodecyl sulfate (SDS), ultracentrifuge, and so on.…”

Optimization of the conditions for rice bran phytate degradation by their own phytases

“…The enzyme was dynamic up to 40°C and the activity declined pointedly to 65% at 60°C and afterward gradually decreased [32]. The hydrolytic rancidity extremely influences the nutritive value and tastefulness of rice bran [33]. Rice bran contains 15-22% oil by weight [34,35].…”