Purification and Properties of Rice Bran Phospholipid Acylhydrolase

Studies on The Mechanism of Lipid-hydrolysing in Rice Bran Part V

Abstract

Two phospholipid acylhydrolases of pI 5.4 and 9.5 in rice bran were purified by precipitation with ammonium sulfate and column chromatography on n-decylamine-Sepharose 4B, phosphatidylcholine-AH-Sepharose 4B and isoelectric focusing, up to the specific activity of 119 and 953-fold, respectively. The main phospholipid acylhydrolase (pI 9.5) showed estimated molecular weight of about 40, 000 when determined by gel filtration on a TOYOPEARL HW-50F column. The enyme had optimum pH of 8.0-9.0 and showed the highest activity at 37°C. There was an obligatory requirement of calcium ion and 0.2mM of calcium ion was essential for maximal activity. It was stable below pH 8.0 and 30°C, inhibited by Al³⁺, Co²⁺, Cu²⁺ and EDTA.