12-Lipoxygenase from porcine leukocytes was partially purified by using of DEAE-Toyopearl chromatography (pH 7,5). Phosphatidylcholine and Phosphatidylinositol in reaction mixtures with mixed micelles Lubrol PX / linoleic acid inhibited the enzyme. The pH-optimum of lipoxygenase reaction in presence of phospholipids shifted into alkaline region. In the absence of phospholipids 3 additional substrate molecules bound with enzyme-substrate complex. In the presence of either phosphatidylcholine of phosphatidylinositol up to 2 substrate molecules bound with enzyme-substrate complex. The phospholipids competed with linoleic acid for one of the enzyme binding centers. A kinetic scheme of 12-lipoxygenase reaction has been proposed: formula represented Phosphatidylinositol lowered the values of Ks and Kns of the reaction of linoleic acid oxydation by 12-lipoxygenase, while phosphatidylcholine had opposite effect on these parameters. We suppose that phospholipids can regulate 12-lipoxygenase activity via control of the enzyme affinity to the substrate (polyunsaturated fatty acid).
|Original language||English (US)|
|Number of pages||2|
|Journal||Ukrain'skyi Biokhimichnyi Zhurnal|
|State||Published - Dec 1 1999|
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