Non-heme iron-containing dioxygenase that catalyzes the stereo-specific peroxidation of free and esterified polyunsaturated fatty acids generating a spectrum of bioactive lipid mediators (PubMed:9305900, PubMed:10965849, PubMed:10625675, PubMed:16143298, PubMed:16112079, PubMed:15558016, PubMed:27435673). Catalyzes the peroxidation of arachidonate and linoleate into (8S)-HPETE and (9S)-HPODE respectively (PubMed:9305900, PubMed:10965849, PubMed:10625675, PubMed:16143298, PubMed:16112079, PubMed:15558016, PubMed:27435673). In addition to generate (8S)-HPETE from free arachidonic acid (AA), may produce other HETE isomers from phospholipid-esterified polyunsaturated fatty acids and minor products derived from (8S)-HPETE itself that may include leukotriene A4 and 8,15-diHPETE (PubMed:16143298, PubMed:16112079, PubMed:27435673). With free arachidonate as substrate, has no detectable 15S-lipoxygenase activity and only displays a 8S-lipoxygenase activity (PubMed:10625675, PubMed:16112079, PubMed:16143298, PubMed:15558016, PubMed:10965849, PubMed:9305900). However may have a 15S-lipoxygenase activity with (8S)-HPETE to produce (8S,15S)-diHPETE and when oxidizes directly arachidonic acid esterified to membrane-bound phospholipids to produce a phospholipid-esterified 15-HpETE (PubMed:27435673, PubMed:16112079, PubMed:16143298). May also catalyze (15S)-HPETE peroxidation to produce 8,15-diHPETE (PubMed:16112079). May play a role in keratinocyte differentiation through activation of the peroxisome proliferator activated receptor signaling pathway (PubMed:10965849). (9Z,12Z)-octadecadienoate + O2 = (9S)-hydroperoxy-(10E,12Z)-octadecadienoate (5Z,8Z,11Z,14Z)-eicosatetraenoate + O2 = (8S)-hydroperoxy-(5Z,9E,11Z,14Z)-eicosatetraenoate (15S)-hydroperoxy-(5Z,8Z,11Z,13E)-eicosatetraenoate + O2 = (8S,15S)-dihydroperoxy-(5Z,9E,11Z,13E)-eicosatetraenoate (8S)-hydroperoxy-(5Z,9E,11Z,14Z)-eicosatetraenoate + O2 = (8S,15S)-dihydroperoxy-(5Z,9E,11Z,13E)-eicosatetraenoate 1-octadecanoyl-2-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-sn-glycero-3-phosphocholine + O2 = 1-octadecanoyl-2-(15-hydroperoxy-5Z,8Z,11Z,13E-eicosatetraenoyl)-sn-glycero-3-phosphocholine a 1-acyl-2-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-sn-glycero-3-phospho-(1D-myo-inositol) + O2 = a 1-acyl-2-(15-hydroperoxy-5Z,8Z,11Z,13E-eicosatetraenoyl)-sn-glycero-3-phospho-(1D-myo-inositol) a 1-acyl-2-(8Z,11Z,14Z-eicosatrienoyl)-sn-glycero-3-phospho-(1D-myo-inositol) + O2 = a 1-acyl-2-(15-hydroperoxy-8Z,11Z,13E-eicosatrienoyl)-sn-glycero-3-phospho-(1D-myo-inositol) (5Z,8Z,11Z,14Z)-eicosatetraenoate + O2 = 9-hydroperoxy-(5Z,7E,11Z,14Z)-eicosatetraenoate (5Z,8Z,11Z,14Z)-eicosatetraenoate + O2 = 11-hydroperoxy-(5Z,8Z,12E,14Z)-eicosatetraenoate (8Z,11Z,14Z)-eicosatrienoate + O2 = 15-hydroperoxy-(8Z,11Z,13E)-eicosatrienoate Binds 1 Fe cation per subunit. The highest catalytic efficiency is observed with arachidonate followed by (8S)-HPETE and(15S)-HPETE with similar efficiencies (PubMed:16112079). kcat is 0.22 sec(-1) for (5Z,8Z,11Z,14Z)-eicosatetraenoate. kcat is 0.045 sec(-1) for (8Z,11Z,14Z)-eicosatrienoate (PubMed:27435673). Lipid metabolism; hydroperoxy eicosatetraenoic acid biosynthesis. Predominantly cytosolic; becomes enriched at membranes upon calcium binding. Expressed in epidermis and brain (PubMed:9305900, PubMed:9518531). No expression found in heart, spleen, liver, skeletal muscle, kidney or testis. By phorbol ester. The PLAT domain can bind calcium ions; this promotes association with membranes. Belongs to the lipoxygenase family.