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 0.2 M phosphate buffer pH 7, fractionating with 30-60% (NH(4))(2)SO(4), 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 30 min at 70 degrees C, 20 min at 80 degrees C and 10 min at 90 degrees C. The enzyme could be inhibited by MgCl(2), ZnCl(2), KCl, BHA, vitamin E, vitamin C, and BHT; however, CaCl(2) acted as the enzyme activator.