Title : Analysis of hydroperoxide-induced tyrosyl radicals and lipoxygenase activity in aspirin-treated human prostaglandin H synthase-2.

Pub. Date : 1997 Feb 18

PMID : 9048568






11 Functional Relationships(s)
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1 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. Aspirin prostaglandin-endoperoxide synthase 2 Homo sapiens
2 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. Aspirin prostaglandin-endoperoxide synthase 2 Homo sapiens
3 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. Aspirin prostaglandin-endoperoxide synthase 2 Homo sapiens
4 We now have found the ASA-treated PGHS-2 radical to be indistinguishable from that in control PGHS-2. Aspirin prostaglandin-endoperoxide synthase 2 Homo sapiens
5 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. Aspirin prostaglandin-endoperoxide synthase 2 Homo sapiens
6 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. Aspirin prostaglandin-endoperoxide synthase 2 Homo sapiens
7 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. Aspirin prostaglandin-endoperoxide synthase 2 Homo sapiens
8 Native and ASA-treated PGHS-2 had lipoxygenase K(m) values considerably higher than that of the control PGHS-2 cyclooxygenase. Aspirin prostaglandin-endoperoxide synthase 2 Homo sapiens
9 Native and ASA-treated PGHS-2 had lipoxygenase K(m) values considerably higher than that of the control PGHS-2 cyclooxygenase. Aspirin prostaglandin-endoperoxide synthase 2 Homo sapiens
10 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. Aspirin prostaglandin-endoperoxide synthase 2 Homo sapiens
11 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. Aspirin prostaglandin-endoperoxide synthase 2 Homo sapiens