Characterization of 11-HETE and 15-HETE, together with prostacyclin, as major products of the cyclooxygenase pathway in cultured rat aorta smooth muscle cells.

Bailey, J. Martyn; Bryant, Robert W.; Whiting, J; Salata, Konrad

doi:10.1016/s0022-2275(20)37865-2

Cited by 82 publications

(7 citation statements)

References 28 publications

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Section: Discussionmentioning

confidence: 99%

“…Lipoxygenase catalysis is a well-established side reaction of PGHS (Bailey et al, 1983;Setty et al, 1985;Hecker et al, 1987). The observed inhibition of lipoxygenase activity by anti-cyclooxygenase agents (Bailey et al, 1983;Setty et al, 1985) indicates that lipoxygenase catalysis occurs in the cyclooxygenase active site. In addition, the underlying chemical transformation in the lipoxygenase reaction, oxygen addition to a 1,4-pentadiene group in an unsaturated fatty acid, is shared by the cyclooxygenase reaction itself.…”

Section: Discussionmentioning

confidence: 99%

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Analysis of Hydroperoxide-Induced Tyrosyl Radicals and Lipoxygenase Activity in Aspirin-Treated Human Prostaglandin H Synthase-2

et al. 1997

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A hydroperoxide-induced tyrosyl radical has been proposed as a key cyclooxygenase intermediate for the "basal" isoform of prostaglandin H synthase (PGHS-1). In the present study with the "inducible" isoform (PGHS-2), hydroperoxide was also found to generate a radical in high yield, a wide singlet at g = 2.0058 (29 G peak to trough). Reaction of PGHS-2 with a tyrosine-modifying reagent, tetranitromethane (TNM), resulted in cyclooxygenase inactivation and a much narrower radical EPR signal (22 G peak to trough). Addition of a cyclooxygenase inhibitor, nimesulide, similarly resulted in a narrow PGHS-2 radical. In PGHS-1, cyclooxygenase inhibition by tyrosine nitration with TNM or by active site ligands leads to generation of a narrow EPR instead of a wide EPR, with both signals originating from authentic tyrosyl radicals, indicating that the hydroperoxide-induced radicals in PGHS-2 are also tyrosyl radicals. Treatment of PGHS-2 with aspirin (acetyl salicylic acid, ASA) was previously shown to result in acetylation of a specific serine residue, cyclooxygenase inhibition, and increased lipoxygenase activity. Acetylation of PGHS-1 by ASA, in contrast, inhibited both lipoxygenase and cyclooxygenase activity. We now have found the ASA-treated PGHS-2 radical to be indistinguishable from that in control PGHS-2. Addition of nimesulide to ASA-treated PGHS-2 inhibited the lipoxygenase and resulted in a narrow radical EPR like that seen in PGHS-2 treated with TNM or nimesulide alone. Retention of PGHS-2 oxygenase activity was thus associated with retention of the native radical, and loss of activity was associated with alteration of the radical. Both native and ASA-treated PGHS-2 produced only the R stereoisomer of 11- and 15-HETE, demonstrating that the lipoxygenase stereochemistry was not changed by ASA. Native and ASA-treated PGHS-2 had lipoxygenase K(m) values considerably higher than that of the control PGHS-2 cyclooxygenase. Taken together, these results suggest that the same PGHS-2 tyrosyl radical serves as the oxidant for both cyclooxygenase and lipoxygenase catalysis and that acetylation of PGHS-2 by ASA favors arachidonate binding in an altered conformation which results in abstraction of the pro-R hydrogen from C13 and formation of 11(R)- and 15(R)-HETE.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Analysis of Hydroperoxide-Induced Tyrosyl Radicals and Lipoxygenase Activity in Aspirin-Treated Human Prostaglandin H Synthase-2

et al. 1997

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“…96 Furthermore, since the COX reaction generates minor quantities of hydroxy fatty acids, the 2:1 reaction stoichiometry is not absolutely correct. 77,82,97,98,85 The latter concern is usually only problematic in studies of enzyme inhibition or sitedirected mutagenesis, in which the ratio of hydroxy fatty acid to PG is significantly increased. An alternative method for monitoring cyclooxygenase activity is to use radiolabeled fatty acid as substrate and chromatographically separate and quantify each of the reaction products.…”

Section: Assays For Peroxidase and Cyclooxygenase Activitiesmentioning

confidence: 99%

“…A disadvantage of the use of the oxygen electrode is the fact that the rate of oxygen diffusion across the electrode membrane may be slower than the rate of the cyclooxygenase reaction under some circumstances, leading to an underestimation of the reaction rate . Furthermore, since the COX reaction generates minor quantities of hydroxy fatty acids, the 2:1 reaction stoichiometry is not absolutely correct. ,,,, The latter concern is usually only problematic in studies of enzyme inhibition or site-directed mutagenesis, in which the ratio of hydroxy fatty acid to PG is significantly increased. An alternative method for monitoring cyclooxygenase activity is to use radiolabeled fatty acid as substrate and chromatographically separate and quantify each of the reaction products.…”

Section: Assays For Peroxidase and Cyclooxygenase Activitiesmentioning

confidence: 99%

Mechanism of Free Radical Oxygenation of Polyunsaturated Fatty Acids by Cyclooxygenases

2003

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“…It is worth noting that COX can also catalyse a LOX-type reaction which leads to formation of HETEs. This occurs when the COX dioxygenase activity, where one dioxygen molecule is introduced to AA, is not followed by a subsequent endoperoxide formation [ 68 , 69 ]. This is the result of the reduction of peroxyl radicals to form a hydroperoxide instead of undergoing cyclization.…”

Section: Oxylipin Generation In Innate Immune Cellsmentioning

confidence: 99%

The role of procoagulant phospholipids on the surface of circulating blood cells in thrombosis and haemostasis

et al. 2022

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Phospholipids (PLs) are found in all cell types and are required for structural support and cell activation signalling pathways. In resting cells, PLs are asymmetrically distributed throughout the plasma membrane with native procoagulant aminophospholipids (aPLs) being actively maintained in the inner leaflet of the membrane. Upon platelet activation, aPLs rapidly externalize to the outer leaflet and are essential for supporting the coagulation cascade by providing binding sites for factors in the cell-based model. More recent work has uncovered a role for enzymatically oxidized PLs (eoxPLs) in facilitating coagulation, working in concert with native aPLs. Despite this, the role of aPLs and eoxPLs in thrombo-inflammatory conditions, such as arterial and venous thrombosis, has not been fully elucidated. In this review, we describe the biochemical structures, distribution and regulation of aPL externalization and summarize the literature on eoxPL generation in circulating blood cells. We focus on the currently understood role of these lipids in mediating coagulation reactions in vitro , in vivo and in human thrombotic disease. Finally, we highlight gaps in our understanding in how these lipids vary in health and disease, which may place them as future therapeutic targets for the management of thrombo-inflammatory conditions.

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Characterization of 11-HETE and 15-HETE, together with prostacyclin, as major products of the cyclooxygenase pathway in cultured rat aorta smooth muscle cells.

Cited by 82 publications

References 28 publications

Analysis of Hydroperoxide-Induced Tyrosyl Radicals and Lipoxygenase Activity in Aspirin-Treated Human Prostaglandin H Synthase-2

Analysis of Hydroperoxide-Induced Tyrosyl Radicals and Lipoxygenase Activity in Aspirin-Treated Human Prostaglandin H Synthase-2

Mechanism of Free Radical Oxygenation of Polyunsaturated Fatty Acids by Cyclooxygenases

The role of procoagulant phospholipids on the surface of circulating blood cells in thrombosis and haemostasis

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