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Transformations of 5‐HETE by activated keratinocyte 15‐lipoxygenase and the activation mechanism
Author(s) -
Green Floyd A.
Publication year - 1990
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02536012
Subject(s) - lipoxygenase , eicosanoid , arachidonic acid , chemistry , hydroxyeicosatetraenoic acid , enzyme , biochemistry , keratinocyte , mechanism of action , peroxidase , lipid signaling , stereochemistry , microbiology and biotechnology , biology , in vitro
There is convincing evidence that normal cultured human keratinocytes possess a 15‐lipoxygenase activity which, however, does not appear to manifest itself without cell membrane damage. When “activated”, this enzyme transforms arachidonic acid into 15‐hydroxyeicosatetraenoic acid (15‐HETE), and linoleic acid into 13‐hydroxyoctadecadienoic acid, presumably by peroxidase action on their respective hydroperoxy intermediates. Normal but notmembrane‐damaged keratinocytes metabolize exogenous 5‐HETE, principally by esterifying the eicosanoid intact, primarily in the triacylglycerol fraction. In the present study, membrane‐damaged keratinocytes were found to transform 5‐HETE to 5,15‐diHETE and also to a lipoxin‐like group of tetraenes. Similar, if not identical, tetraenes were produced by action of the keratinocyte enzyme on 5(S),15(S)‐diHETE, which points to the role of the latter as an intermediate between 5‐HETE and the tetraenes. A direction for further study of the mechanism of the “activation” step is presented.