Kinetics of the oxidation of p-coumaric acid by prostaglandin H synthase and hydrogen peroxide. [Erratum to document cited in CA118:54981]

Biochemistry ◽  
1994 ◽  
Vol 33 (37) ◽  
pp. 11404-11404
Author(s):  
Marica Bakovic ◽  
H. Brian Dunford
Keyword(s):  
Hydrogen Peroxide ◽  
Coumaric Acid ◽  
Prostaglandin H Synthase ◽  
Prostaglandin H ◽  
Kinetics Of

Ibuprofen protects human endothelial cell prostaglandin H synthase from hydrogen peroxide

1996 ◽  
Vol 271 (6) ◽  
pp. C1879-C1886 ◽  
Author(s):  
D. A. Wessels ◽  
S. L. Hempel
Keyword(s):  
Hydrogen Peroxide ◽  
Endothelial Cells ◽  
Arachidonic Acid ◽  
Endothelial Cell ◽  
Arachidonic Acid Release ◽  
Human Endothelial Cells ◽  
Prostaglandin H Synthase ◽  
Cyclooxygenase Activity ◽  
Acid Release ◽  
Prostaglandin H

Human endothelial cells exposed to H2O2 demonstrate decreased prostacyclin (PGI2) synthesis due to decreased prostaglandin H synthase (PGH synthase) activity. We tested the hypothesis that PGH synthase activity could be protected from H2O2 by a reversible nonsteroidal anti-inflammatory drug. Experiments demonstrate that ibuprofen if present during H2O2 exposure, protects endothelial cell PGH synthase against the decrease in prostaglandin formation caused by H2O2. Additional studies demonstrated that decreasing arachidonic acid release from cell phospholipids during H2O2 exposure did not protect PGI2 synthesis following H2O2 exposure. In other experiments, ibuprofen did not chelate Fe2+ in a conformation that inhibited the reactivity of Fe2+. In addition, ibuprofen did not scavenge HO. However, we demonstrate that ibuprofen significantly protects purified PGH synthase cyclooxygenase activity from the effects of H2O2. The results confirm the hypothesis. These findings suggest that ibuprofen displaces oxidant species from the cyclooxygenase site of PGH synthase, thereby preventing oxidation of the functional groups important for PGH synthase activity.

Study on N-Demethylation of N,N-Dimethyl-4-aminoazobenzene and N-Nitrosamines by Prostaglandin H Synthase

1997 ◽  
Vol 62 (6) ◽  
pp. 971-980 ◽  
Author(s):  
Marie Stiborová ◽  
Eva Frei ◽  
Heinz H. Schmeiser
Keyword(s):  
Hydrogen Peroxide ◽  
Arachidonic Acid ◽  
Free Radicals ◽  
Seminal Vesicle ◽  
Oxidation Mechanism ◽  
Maximal Velocity ◽  
Prostaglandin H Synthase ◽  
Michaelis Constant ◽  
Prostaglandin H

The in vitro enzymatic metabolism of carcinogenic N,N-dimethyl-4-aminoazobenzene, N-nitroso-N-methylaniline and N-nitroso-N,N-dimethylamine was investigated using ram seminal vesicle microsomal prostaglandin H synthase. Both N-nitrosamines are not converted by the studied enzyme. Formaldehyde is produced by the prostaglandin H synthase catalyzed reaction from N,N-dimethyl-4-aminoazobenzene. Arachidonic acid and hydrogen peroxide serve as cofactors for the oxidation of N,N-dimethyl-4-aminoazobenzene. The apparent Michaelis constant and the maximal velocity values for N,N-dimethyl-4-aminoazobenzene as a substrate are 64 μmol/l and 51.2 nmol HCHO/min/mg protein, respectively. In addition to formaldehyde, N-methyl-4-aminoazobenzene and 4-aminoazobenzene, two unknown substances are the products of the N,N-dimethyl-4-aminoazobenzene oxidation. The oxidation of N,N-dimethyl-4-aminoazobenzene catalyzed by prostaglandin H synthase is inhibited by glutathione, ascorbate and NADH. The results suggest that prostaglandin H synthase metabolizes N,N-dimethyl-4-aminoazobenzene through a one-electron oxidation mechanism, giving rise to free radicals.

Reaction and Free Radical Kinetics of Prostaglandin H Synthase with Manganese Protoporphyrin IX as the Prosthetic Group

Biochemistry ◽  
1994 ◽  
Vol 33 (18) ◽  
pp. 5428-5439 ◽  
Author(s):  
Richard J. Kulmacz ◽  
Graham Palmer ◽  
Chunhong Wei ◽  
Ah-Lim Tsai
Keyword(s):  
Free Radical ◽  
Protoporphyrin Ix ◽  
Prostaglandin H Synthase ◽  
Prosthetic Group ◽  
Prostaglandin H ◽  
Kinetics Of

Rapid kinetics of tyrosyl radical formation and heme redox state changes in prostaglandin H synthase-1 and -2

1999 ◽  
Vol 59 (1-6) ◽  
pp. 120
Author(s):  
Ah-Lim Tsai ◽  
Gang Wu ◽  
Graham Palmer ◽  
Bijan Bambai ◽  
James A. Koehn ◽  
...  
Keyword(s):  
Redox State ◽  
Radical Formation ◽  
Tyrosyl Radical ◽  
Prostaglandin H Synthase ◽  
State Changes ◽  
Prostaglandin H ◽  
Rapid Kinetics ◽  
Kinetics Of

scholarly journals Comparison of the Peroxidase Reaction Kinetics of Prostaglandin H Synthase-1 and -2

1999 ◽  
Vol 274 (23) ◽  
pp. 16162-16167 ◽  
Author(s):  
Guqiang Lu ◽  
Ah-Lim Tsai ◽  
Harold E. Van Wart ◽  
Richard J. Kulmacz
Keyword(s):  
Reaction Kinetics ◽  
Prostaglandin H Synthase ◽  
Peroxidase Reaction ◽  
Prostaglandin H ◽  
Kinetics Of

scholarly journals Rapid Kinetics of Tyrosyl Radical Formation and Heme Redox State Changes in Prostaglandin H Synthase-1 and -2

1999 ◽  
Vol 274 (31) ◽  
pp. 21695-21700 ◽  
Author(s):  
Ah-lim Tsai ◽  
Gang Wu ◽  
Graham Palmer ◽  
Bijan Bambai ◽  
James A. Koehn ◽  
...  
Keyword(s):  
Redox State ◽  
Radical Formation ◽  
Tyrosyl Radical ◽  
Prostaglandin H Synthase ◽  
State Changes ◽  
Prostaglandin H ◽  
Rapid Kinetics ◽  
Kinetics Of
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