Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.11.1.7 (peroxidase)
 65,474 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Metabolism of 2-amino-4-(5-nitro-2-furyl)thiazole (ANFT) by a variety of different peroxidases was examined. Metabolism of ANFT was measured by the binding of radiolabeled substrates to protein and DNA. Prostaglandin hydroperoxidase but not horseradish peroxidase, lactoperoxidase, or chloroperoxidase metabolically activated ANFT. All four peroxidases catalyzed the binding of benzidine to protein and DNA. With peroxide substrates, peroxidase-catalyzed binding of both carcinogens was observed with or without molecular oxygen. Arachidonic acid-dependent binding of ANFT and benzidine by prostaglandin endoperoxide synthetase was inhibited by anaerobic conditions and aspirin. Chloroperoxidase activation of benzidine was also inhibited by aspirin. Vitamin E inhibited activation of both carcinogens by all enzymes examined. Prostaglandin hydroperoxidase-catalyzed binding of benzidine to protein was inhibited by the 5-nitrofurans ANFT and 3-hydroxymethyl-1-(([3-(5-nitro-2-furyl)allydidene] amino))hydantoin and acetaminophen, while only acetaminophen inhibited horseradish peroxidase-catalyzed binding. These results indicate that different peroxidases may exhibit specificity with respect to their activation of carcinogens. Only prostaglandin hydroperoxidase activated the 5-nitrofuran ANFT, while a number of peroxidases activated the aromatic amine benzidine.
 ...
PMID:Peroxidase metabolism of the urinary bladder carcinogen 2-amino-4-(5-nitro-2-furyl)thiazole. 640 25

p-Phenetidine is metabolized by ram seminal vesicle (RSV) microsomes, horseradish peroxidase (HRP) and rat liver microsomes to protein-binding products. These reactions are very rapid and depend on the presence of arachidonic acid (AA) or various hydroperoxidases. The RSV- and HRP-mediated binding was inhibited more than 80% by the addition of reduced glutathione (1 mM) or the antioxidant butylated hydroxyanisole (0.5 mM). Indomethacin (100 microM) and acetylsalicylic acid (1 mM) reduced the AA-dependent reaction in RSV microsomes to less than 5% of control values. When hydrogen peroxide replaced AA, the RSV/H2O2-supported binding in the presence of 50 microM p-phenetidine proceeded at rates similar to that observed with RSV/AA. Unlike the AA-dependent reaction, the H2O2-supported reaction showed no inhibition of protein binding at higher p-phenetidine concns. The data in this report are consistent with a peroxidatic activation of p-phenetidine possibly involving an amine radical catalyzed by prostaglandin synthase (PGS) present in RSV microsomes as well as by other peroxidases. The mechanism for this activation and physiological implications are discussed.
 ...
PMID:Hydroperoxide-dependent activation of p-phenetidine catalyzed by prostaglandin synthase and other peroxidases. 640 83

We have examined the prostaglandin endoperoxide synthetase-dependent metabolism of the arylamine carcinogen 2-aminofluorene (2-AF). Ram seminal vesicle microsomes fortified with arachidonic acid metabolize 2-AF to products covalently bound to microsomal macromolecules, water-soluble metabolites, and two organic extractable metabolites. The organic extractable metabolites were identified by co-chromatography, uv-visible spectrophotometry, and mass spectrometry as 2-nitrofluorene and 2,2'-azobisfluorene (azofluorene). Hydrogen peroxide also supports 2-AF metabolism to the same products, suggesting that the hydroperoxidase activity of prostaglandin endoperoxide synthetase is responsible for the co-oxidation. The highly reactive oxygenated metabolites of 2-AF, N-hydroxy-2-AF, and 2-nitrosofluorene, are metabolized by prostaglandin endoperoxide synthetase to one major product, 2-nitrofluorene. The metabolism of 2-AF, N-hydroxy-2-AF, and 2-nitrosofluorene is extremely rapid, reaching completion in less than 30 s. The horseradish peroxidase/H2O2 system also metabolites 2-AF to 2-nitrofluorene and azofluorene. The chloroperoxidase/H2O2 system, however, yields primarily 2-nitrosofluorene from 2-AF. These results suggest that 2-AF is oxidized to an electrophilic intermediate(s) by prostaglandin endoperoxide synthetase, which either binds covalently to tissue macromolecules or is further rapidly oxidized to 2-nitrofluorene and azofluorene. Furthermore, this reaction probably proceeds through a free radical mechanism similar to that of horseradish peroxidase.
 ...
PMID:The oxidation of 2-aminofluorene by prostaglandin endoperoxide synthetase. Comparison with other peroxidases. 640 86

Addition of ferrous sulfate to a solution containing peroxy-methyl arachidonate resulted in cleavage of the peroxy group on the methyl arachidonate as assessed by absorption at 232nm. The results suggest that ferrous iron can be involved in the reduction of fatty acid peroxides and supports the possibility that the peroxidase component of the fatty acid cyclooxygenase occurs via a Fenton type reaction.
 ...
PMID:Evidence that the peroxidase of the fatty acid cyclooxygenase acts via a Fenton type of reaction. 641 67

Human ceruminous glands were treated for the histochemical demonstration of glycoproteins and of several enzymatic activities. Neutral mucopolysaccharides were detected in the cytoplasm and pigment granules of the epithelial cells, and acid glycoproteins were recognized only in a thin apical zone corresponding to the glycocalyx. Lysosomal enzymes were demonstrated within cytoplasmic granules, while peroxidase, G6PD and 6PGD showed a diffuse reactivity through the entire cytoplasm of the secretory cells. Age and sex-related differences were observed with respect to 17 beta-HSD and the 3 beta-HSD, whose reactivity appeared more intense in the young and in the female than in the old and in the male glands. Finally, all the ceruminous cells showed a strong prostaglandin synthetase reactivity.
 ...
PMID:Human ceruminous glands: a histochemical study. 641 33

A variety of prostaglandin synthetase inhibitors are cooxygenated during arachidonic acid peroxidation catalyzed by rat renal medulla prostaglandin synthetase or soybean lipoxygenase. Phenylbutazone, aminopyrine, 1,3-diphenylisobenzofuran, paracetamol, p-aminophenol, p-phenetidine and other o- and m-substituted aminophenol derivatives were cooxygenated, whereby prostaglandin synthetase inhibition was significantly weakened due to the formation of less inhibitory metabolites. In contrast, the inhibitory potency of diclofenac, indomethacin and phenacetin and its analogues remained unchanged during prostaglandin synthesis inhibition, because these compounds were no suitable cooxygenation substrates. Evidence is given that quinone imines may not be involved in the cooxidative metabolism of paracetamol and other aminophenols. As to the mechanisms of cooxygenation of suitable substrates dependent on their chemical structures either the arachidonic acid oxygenase or the subsequent hydroperoxidase reaction may trigger the oxygenation. 1,3-Diphenylisobenzofuran is metabolized during the formation of arachidonic acid hydroperoxides in contrast to paracetamol, which requires an additional peroxidase reaction to yield reactive metabolites.
 ...
PMID:Decreasing inhibitory potency of prostaglandin synthetase inhibitors during their cooxidative metabolism. Studies on aminophenols, pyrazolon derivatives and 1,3-diphenylisobenzofuran. 641 40

The prostaglandin synthase and horseradish peroxidase catalyzed binding of p-phenetidine to DNA was investigated. The addition of arachidonic acid to an incubation containing ram seminal vesicle microsomes, [14C]p-phenetidine and DNA resulted in a rapid incorporation of radioactivity into DNA. This was inhibited by greater than 75% by indomethacin (0.1 mM) or butylated hydroxyanisole (0.5 mM). Hydrogen peroxide was as efficient as arachidonic acid in mediating the activation of p-phenetidine thus implicating the involvement of the hydroperoxidase activity of prostaglandin synthase in this reaction. Horseradish peroxidase and hydrogen peroxide also catalyzed the activation of p-phenetidine to DNA-binding metabolites. Reduced glutathione (GSH) stimulated the binding of p-phenetidine to DNA by greater than 3-fold in both the prostaglandin synthase and the horseradish peroxidase system, whereas cysteine and N-acetylcysteine reduced the DNA-binding in the prostaglandin synthase system by up to 62% under the conditions used. Furthermore, water-soluble metabolites formed in the presence of GSH also bound to DNA. Seventy-two hour dialysis of DNA samples from incubations with GSH present reduced the amount of bound material by 75%. In contrast, the radioactivity which associated with DNA in the absence of GSH was not decreased by dialysis.
 ...
PMID:Prostaglandin synthase and horseradish peroxidase catalyzed DNA-binding of p-phenetidine. 642 1

The metabolism of procarbazine was studied using spin-trapping techniques. The oxidation of procarbazine, catalyzed by horseradish peroxidase, prostaglandin synthetase [ram seminal vesicle (RSV) microsomes] or rat hepatic microsomal cytochrome P-450, produced carbon-centered free radicals. Cytochrome P-450 also catalyzed this oxidation in the presence of hydrogen peroxide. Horseradish peroxidase activation of procarbazine formed both the methyl radical and the N-isopropylbenzylamide radical [(CH3)2CHNHCO(C6H4)CH2.]. In the presence of RSV or rat hepatic microsomes, mostly the benzyl-type radical was trapped, presumably due to the reactivity of the methyl radical.
 ...
PMID:Metabolic activation of procarbazine. Evidence for carbon-centered free-radical intermediates. 643 96

Microsomes from ram seminal vesicles or purified prostaglandin H synthase supplemented with either arachidonic acid or prostaglandin G2 formed an unstable spectral intermediate with maxima at 430 nm, 525 nm and 555 nm and minima at 410 nm, 490 nm and 630 nm. At -15 degrees C the band at 430 nm disappeared within 4 min whereas the trough at 410 nm increased three fold. At higher temperatures (10-37 degrees C) spectral complex formation and decay were observed in less than 1 s. An apparent KS-value of about 3 microM was determined for the titration of purified prostaglandin synthase with prostaglandin G2 at -20 degrees C. Substrates for cooxidation reactions of prostaglandin synthase such as phenol, hydroquinone and reduced glutathione as well as the peroxidase inhibitors cyanide and azide inhibited the prostaglandin G2-induced spectral complex formation. The oxene donor iodosobenzene and hydrogen peroxide formed a spectral intermediate analogous to the complex observed with prostaglandin G2 or arachidonic acid in ram seminal vesicle microsomes as well as with the purified prostaglandin synthase. These results are interpreted as the formation of a ferryl-oxo complex (FeO)3+ of the heme of prostaglandin synthase with prostaglandin G2 analogous to the formation of compound I of horseradish peroxidase.
 ...
PMID:Spectral intermediates of prostaglandin hydroperoxidase. 643 22

Rat liver fixed by perfusion with low glutaraldehyde concentrations was incubated in diaminobenzidine-containing medium to stain for peroxidase. Endogenous peroxidatic activity was found not only in Kupffer cells but also in the endothelial cells lining the sinusoids and central veins. The reaction product was localized in the nuclear envelope and endoplasmic reticulum. The peroxidatic activity in endothelial cells showed a concentration-dependent sensitivity to glutaraldehyde: in liver samples fixed with 0.25% glutaraldehyde, approx. 23% of the sinusoidal endothelial cells and 65% of central vein endothelium were peroxidase-positive; with 0.5% glutaraldehyde, only approx. 8% of the sinusoidal endothelial cells contained detectable amounts of the reaction product; with 1.5% glutaraldehyde all endothelial cells were consistently peroxidase-negative. No peroxidatic activity could be found in liver endothelial cells following isolation by centrifugal elutriation. Endothelial cell peroxidase may possibly be involved in defense responses of liver and/or, as a part of prostaglandin synthase system, in prostanoid production.
 ...
PMID:Peroxidase-positive endothelial cells in rat liver. 644 44


<< Previous 1 2 3 4 5 6 7 8 Next >>