Isolation and Some Characteristics of Lipoxygenase from Aromatic Brown Rice (Oryza Sativa L.) cv. Khao Dawk Mali 105

Lipoxygenase from Khao Dawk Mali 105 aromatic brown rice was isolated by extracting brown rice liquid nitrogen powder using 0.2M phosphate buffer pH 7, fractionating with 30-60% (NH4)2SO4, dialyzing and gel filtration on Sephadex G-200. The optimum pHs for dialyzed lipoxygenase activity were around 7.5 and 9.5. The enzyme appeared to be completely inactivated after heating 30min at 70C, 20min at 80C and 10min at 90C. The enzyme could be inhibited by MgCl2, ZnCl2, KCl, BHA, vitamin E, vitamin C, and BHT; however, CaCl2 acted as the enzyme activator.