Cereal Chem 61:392 - 398. | VIEW
Isolation of Lipoxygenase Isoenzymes from Flour of Durum Wheat Endosperm.
C. C. Hsieh and C. E. McDonald. Copyright 1984 by the American Association of Cereal Chemists, Inc.
Three lipoxygenase isoenzymes from flour of durum wheat endosperm were isolated and partially purified by ammonium sulfate fractionation and by DEAE- and CM-cellulose column chromatography. The tree isoenzymes are designated as lipoxygenase-l (L-l), lipoxygenase-2 (L-2), and lipoxygenase-3 (L-3), according to their inverse order of elution from CM-cellulose column.The L-3 isoenzyme (first off the column) and the L-2 isoenzyme (next off the column) had optimum lipoxygenase activity at pH 4.8 and the L-l (last off the column) had activity optima at pH 10.2 and 11.4. The L-l isoenzyme also had peroxidase activity with an optimum at pH 4.8. The L-l was further fractionated by preparative disk polyacrylamide gel electrophoresis. Agarose-con A affinity chromatography of L-l gave three active fractions, all having peroxidase, lipoxygenase, and carotene bleaching activity. Both L-2 and L-3 isoenzymes exhibited optimum carotene bleaching activity at pH 6.6, whereas L-l had its optimum at pH 10.2. All three isoenzymes required high concentration of linoleic acid for carotene bleaching, and the L-l isoenzyme also required high linolec acid concentration for linoleic acid oxidation. The relative lipoxygenase activity in crude extract from endosperm flour of Golden Ball durum wheat was 21.3, 33.8, and 44.9%, respectively, for L-l, L-2, and L-3 at their pH of optimum activity.