[Role of phospholipids in the regulation of activity of porcine leukocyte 12-lipoxygenase].
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: Phosphatidylinositol lowered the values of Ks and Kns of the reaction of linoleic acid oxidation 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).
Butovich
I A
IA
Institute of Bioorganic Chemistry and Petrolchemistry, NAS of Ukraine, Kyiv.
Kharchenko
O V
OV
D000818:Animals; D001092:Arachidonate 12-Lipoxygenase / Q000097:blood*; D007700:Kinetics; D007962:Leukocytes / Q000201:enzymology*; D019787:Linoleic Acid / Q000378:metabolism*; D010084:Oxidation-Reduction; D010713:Phosphatidylcholines / Q000502:physiology*; D010716:Phosphatidylinositols / Q000502:physiology*; D013552:Swine
D010713:Phosphatidylcholines; D010716:Phosphatidylinositols; D019787:Linoleic Acid; D001092:Arachidonate 12-Lipoxygenase