Purification and characterization of broad bean lipoxygenase isoenzymes

Two lipoxygenase isoenzymes, BBL-1 and BBL-2, were purified from broad bean s. Fractionation of globulins and albumins by ionic strength was preferred to the classical water extraction system and the ammonium sulfate fractiona tion as initial purification steps. From the albumin fraction, BBL-1 and BB L-2 were purified 17.6 and 35.7-fold, respectively, by conventional gel. fi ltration and ion-exchange chromatography. The molecular weight of both BBL- 1. and BBL-2 was 97 kDa with a maximal activity around pH 5.8; however, the y showed a significant difference in their K-m values for linoleic acid: 2. 3 and 0.25 mM for BBL-1 and BBL-2, respectively. BBL-1 produced hydroperoxi des and ketodienes while BBL-2 produced exclusively hydroperoxides.