title: 15-Lipoxygenase in human platelets.
abstract: The metabolism of arachidonic acid by washed human platelets was investigated. [1-14C]Arachidonic acid was extensively converted to [1-14C]12-hydroxyeicosatetraenoic acid. In addition, several minor labeled products were formed with a considerably lower specific activity, indicating their preferential formation from endogenous substrate. These were dihydroxy metabolites of arachidonic acid with conjugated triene structures and were identified as 14,15-dihydroxyeicosatetraenoic acid (three isomers) and 8,15-dihydroxyeicosatetraenoic acid (three isomers). The identification was based on comparison with reference compounds with respect to chromatographic properties, characteristic UV spectra, and mass spectrometry of several derivatives. Bradykinin (10(-8)-10(-5) M) was found to enhance the formation of all these compounds. In addition, the monohydroxy acid fraction was found to contain 15-hydroxyeicosatetraenoic acid. The present investigation thus demonstrates the occurrence of a 15-lipoxygenase in human platelets in addition to the previously known 12-lipoxygenase.
mesh_terms: D001091:Arachidonate Lipoxygenases; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000097:blood; D001792:Blood Platelets / Q000201:enzymology*; D001920:Bradykinin / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008084:Lipoxygenase / Q000097:blood* / Q000302:isolation & purification; D013056:Spectrophotometry, Ultraviolet
chemical_list: D001095:Arachidonic Acids; D016718:Arachidonic Acid; D001091:Arachidonate Lipoxygenases; D008084:Lipoxygenase; D001920:Bradykinin