title: Demonstration of a 12-lipoxygenase activity in bovine polymorphonuclear leukocytes.
abstract: In this study we present evidence for the existence of an intrinsic 12-lipoxygenase in the bovine polymorphonuclear leukocyte which differs from the well-known platelet 12-lipoxygenase. Intact bovine polymorphonuclear leukocytes synthesize predominantly 5-lipoxygenase products. However, this 5-lipoxygenase activity disappears completely upon sonication of the cells, whereas a 12-lipoxygenase activity then becomes apparent. This 12-lipoxygenase resembles the platelet 12-lipoxygenase in metabolizing arachidonic acid into 12(S)-hydroxyeicosatetraenoic acid and in being independent of Ca2+ as well as of ATP. The most striking difference between the two 12-lipoxygenases is their behaviour towards linoleic acid. While the platelet 12-lipoxygenase does not convert linoleic acid, the 12-lipoxygenase from bovine polymorphonuclear leukocytes, apparent only in the cell-free system, converts linoleic acid into 13-hydroxyoctadecadienoic acid as efficiently as it converts arachidonic acid into 12-hydroxyeicosatetraenoic acid. This provides a convenient method to distinguish both 12-lipoxygenase activities. The fact that this new 12-lipoxygenase is able to metabolize linoleic acid into 13-hydroxyoctadecadienoic acid suggests that this enzyme, in contrast to platelet 12-lipoxygenase, resembles 5-lipoxygenases in showing a preference for hydrogen abstraction at a position which is determined by the distance to the carboxylic end of the fatty acid.
mesh_terms: D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001092:Arachidonate 12-Lipoxygenase / Q000097:blood*; D001091:Arachidonate Lipoxygenases / Q000097:blood*; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism; D001792:Blood Platelets / Q000201:enzymology; D002118:Calcium / Q000494:pharmacology; D002417:Cattle; D002474:Cell-Free System; D002851:Chromatography, High Pressure Liquid; D006893:Hydroxyeicosatetraenoic Acids / Q000097:blood; D019787:Linoleic Acid; D008041:Linoleic Acids / Q000378:metabolism; D013058:Mass Spectrometry; D009504:Neutrophils / Q000201:enzymology*; D013010:Sonication; D013379:Substrate Specificity
chemical_list: D001095:Arachidonic Acids; D006893:Hydroxyeicosatetraenoic Acids; D008041:Linoleic Acids; D016718:Arachidonic Acid; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D000255:Adenosine Triphosphate; D019787:Linoleic Acid; D001091:Arachidonate Lipoxygenases; D001092:Arachidonate 12-Lipoxygenase; D002118:Calcium