SOME PROPERTIES OF PEA LIPOXYGENASE ISOENZYMES

Four pea lipoxygenase isoenzymes were isolated from pea seeds (Little Marvel variety) by ammonium sulfate fractionation, gel filtration, and ion-exchange chromatography. The two major isoenyzmes, pea lipoxygenase I and II (PL I and PL II), were further purified by isoelectric focusing in a granulated gel. PL I and II were homogeneous proteins and had isoelectric points of 6.25 and 5.82, respectively. The molecular weight of both PL I and II was 95 000 and they had optimum activity between pH's 5 and 7 and no activity above pH 8. The two minor isoenzymes were present at very low concentrations and were active at pH 9, but not at neutral to acid pH's. PL I and PL II differed in pH profiles, substrate specificity, carotene-and chlorophyll-bleaching activity, and in their ability to produce carbonyl compounds during the linoleate oxidation reaction. © 1979, American Chemical Society. All rights reserved.