Open AccessIdentification of novel arachidonic acid metabolites formed by prostaglandin H synthase
Author(s) -
HECKER Markus,
ULLRICH Volker,
FISCHER Christine,
MEESE Claus O.
Publication year - 1987
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1987.tb13587.x
Subject(s) - prostaglandin h2 , chemistry , arachidonic acid , prostaglandin , thromboxane a synthase , prostaglandin d2 , thromboxane a2 , thromboxane , stereochemistry , atp synthase , biochemistry , enzyme , platelet , medicine , receptor
The metabolism of [1‐ 14 C]arachidonic acid by microsomal and purified prostaglandin (PG) H synthase was investigated. HPLC analysis confirmed that arachidonic acid (20:4) was extensively converted into prostaglandin G 2 (PGG 2 ) and/or prostaglandin H 2 (PGH 2 ) but several minor labelled products were formed in addition. Their formation, mediated by PGH synthase was established by inhibition with aspirin and indomethacin [Hecker, M., Hatzelmann, A. & Ullrich, V. (1987) Biochem. Pharmacol. 36 , 851–855]. Upon comparison with authentic reference material these unknown PGH synthase metabolites were identified with respect to chromatographic properties, ultraviolet spectroscopy and mass spectrometry as 11 ( R )‐hydroperoxy‐5 Z ,8 Z ,12 E ,14 Z ‐eicosatetraenoic acid (11‐OOH‐20:4), 12( S )‐hydroperoxy‐5 Z ,8 E ,10 E ‐heptadecatrienoic acid (OOH‐17:3), 12( S )‐hydroxy‐5 Z ,8 E ,10 E ‐heptadecatrienoic acid (OH‐17:3), 15( RS )‐hydroperoxy‐5 Z ,8 Z ,11 Z ,13 E ‐eicosatetraenoic acid (15‐OOH‐20:4), 15( RS )‐hydroxy‐5 Z ,8 Z ,11 Z ,13 E ‐eicosatetraenoic acid (15‐OH‐20:4), 13‐hydroxy‐5 Z ,14 Z ‐prostaglandin H 2 , 15( S )‐hydroxy‐8‐ iso ‐5 Z ,13 E ‐prostaglandin H 2 and 15‐oxo‐prostaglandin H 2 . Unlike PGG 2 and PGH 2 , 8‐ iso ‐PGH 2 , 13‐hydroxy‐PGH 2 and 15‐oxo‐PGH 2 failed to induce aggregation of washed human platelets and to form thromboxane upon incubation with homogeneous human platelet thromboxane synthase. In contrast to the formation of OOH‐17:3, 15‐oxo‐PGH 2 and OH‐17:3 which can be attributed to the heme‐catalyzed decomposition of PGG 2 and PGH 2 , 11‐OOH‐20:4, 15‐(O)OH‐20:4‐, 8 iso ‐PGH 2 and 13‐hydroxy‐PGH 2 represent potential side products of arachidonic acid conversion into PG endoperoxides. Their formation allows to conclude on PGH synthase mechanism and its intermediates for which an extended reaction scheme is proposed.