Purification and Properties of Rice Bran Phosphatidate Phosphatase

Studies on The Mechanism of Lipids-hydrolysing in Rice Bran Part VII

Abstract

Phosphatidate phosphatase (EC 3.1.3.4) extracted from rice bran was purified 222 fold with a yield of 5.2% by ammonium sulfate precipitation and column chromatographi es on decylamin-Sepharose, DEAE-cellulose, chromatofocusing and TOYOPEARL HW-55F. The molecular weight and the isoelectric point of the enzyme were estimated to be 28 0000 and 5.3, respectively. The enzyme showed optimum pH of 5.0 and optimum temperature of 60°C. The enzyme activity increased 1.6 fold with addition 10mM Ca²⁺ and was inhibited by Ni²⁺, Mg²⁺ and PCMB. The enzyme was stable over the pH range of 3.0-8.0 and below 40°C. The Km of the enzyme for phosphatidic acid was estimated to be 1.25×10^-3M