Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04040 (Catalase)
 3,577 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Endogenous hydrogen peroxide (H2O2) release from aortic endothelial cells was studied in the presence of antioxidant enzyme inhibitors, mitochondrial inhibitors, a microsomal cytochrome P-450 inhibitor, and after oxidative stress induced with H2O2 or menadione. Extracellular H2O2 generation was determined spectrofluorometrically using 3-methoxy-4-hydroxy phenylacetic acid, and intracellular H2O2 production (in or near peroxisomes) was measured indirectly using aminotriazole, which inactivates catalase in the presence of H2O2. Extracellular H2O2 release was 0.079 +/- 0.005 nmol/min/mg protein in Hanks' balanced salt solution, was constant during a 120-min incubation period, and was not affected by the cell passage number. The half-life for catalase inactivation with aminotriazole was 23 min. Inhibition of catalase, glutathione reductase, or gamma-glutamylcysteine synthetase did not change the rate of extracellular release of H2O2. Furthermore, inhibition of the mitochondrial respiratory chain (rotenone, antimycin A) or microsomal cytochrome P-450 (8-methoxypsoralen) did not change extracellular H2O2 release or intracellular H2O2 production (at peroxisomes) by endothelial cells or cells in which glutathione reductase was inactivated. When the cells were exposed to exogenous H2O2 (30 microM), extracellular H2O2 was scavenged primarily by the glutathione redox pathway. Exogenously added H2O2 (100 microM) changed intracellular H2O2 production (in or near peroxisomes) only when the glutathione redox cycle was inactivated. Menadione (20 microM), which undergoes intracellular redox cycling, increased extracellular H2O2 release almost 4-fold to 0.3 nmol/min/mg protein. Furthermore, menadione increased peroxisomal H2O2 levels and decreased the half-life for catalase inactivation in the presence of aminotriazole to 13 min. Catalase inhibition increased extracellular H2O2 release during menadione treatment, indicating that H2O2 can diffuse across the plasma membrane during oxidant stress.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Regulation of hydrogen peroxide generation in cultured endothelial cells. 154 Mar 80

In previous papers, we have reported that methylguanidine (MG), a known uremic toxin, was synthesized from creatinine (Cr) by active oxygen generated not only by chemical reagents but also by isolated rat hepatocytes. In this paper, we studied whether or not active oxygen generated by stimulated human neutrophils produces MG from Cr. MG was measured after incubating 2 x 10(6) human neutrophils for 2 h in 1 ml of Hanks' balanced salt solution (pH 7.4) containing 100 mg/dl Cr at 37 degrees C after the addition of phorbol myristate acetate (PMA). MG was measured by high pressure liquid chromatography followed by reaction with 9, 10-phenanthrenequinone. MG was synthesized by the stimulated neutrophils and not by the unstimulated ones. MG synthesis reached a plateau (1.11 +/- 0.03 nmol/120 min/2 x 10(6) cells) at a concentration of 0.125 microM PMA and reached a maximum value (1.95 +/- 0.03 nmol/120 min/2 x 10(6) cells) at a concentration of 100 mg/dl Cr. MG synthesis increased depending on the concentration of neutrophils between 1 and 8 x 10(6)/ml and increased depending on the duration of incubation up to 4 h. MG synthesis was strongly inhibited by superoxide dismutase, by the scavengers of hypochloride (taurine and methionine) and by sodium azide. Catalase and the scavenger of the hydroxyl radical (dimethyl sulfoxide) inhibited MG synthesis less effectively. The effects of the scavengers of active oxygen suggest the participation of active oxygen in MG synthesis from Cr in this system. Among the active oxygen species, superoxide anion and hypochloride play an important role in this system.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Methylguanidine synthesis by active oxygen generated by stimulated human neutrophils]. 259 20

Reactive oxygen species (ROS) are implicated in aging of cartilage and in the pathogenesis of osteoarthritis. However, the biological role of chondrocytes-derived ROS has not been elucidated. An in-vitro model was developed to study the role of chondrocyte-derived ROS in cartilage matrix degradation. The primary articular chondrocytes were cultured and the aggrecan matrix was radiolabeled with 35-sulfate. The labeled aggrecan matrix was washed to remove unincorporated label and chondrocytes were returned to serum free balanced salt solution. The cell-monolayer-matrix sensitivity to oxidative damage due to either hydrogen peroxide or glucose oxidase was established by monitoring the release of labeled aggrecan into the medium. Lipopolysaccharide (LPS) treatment of chondrocyte-monolayer enhanced the release of labeled aggrecan. Catalase significantly prevented the release of labeled aggrecan in LPS-chondrocyte cultures, suggesting a role for chondrocyte-derived hydrogen peroxide in aggrecan degradation. Superoxide dismutase or boiled catalase had no such inhibitory effect. The effect of several antioxidants on LPS-chondrocyte-dependent aggrecan degradation was examined. Hydroxyl radical scavengers (mannitol and thiourea) significantly decreased aggrecan degradation. A spin trapping agent N-tert-butyl-phenylnitrone (but not its inactive analog tert-butyl-phenylcarbonate) significantly decreased aggrecan degradation. Butylated hydroxytoluene also inhibited aggrecan degradation, whereas the other lipophilic antioxidant tested, propyl gallate, had a marked dose-dependent inhibitory effect. These data indicate that general antioxidants, hydroxyl radical scavengers, antioxidant vitamins, iron chelating agents, lipophilic antioxidants, and spin trapping agents can influence chondrocyte-dependent aggrecan degradation. These studies support the role of a chondrocyte-dependent oxidative mechanism in aggrecan degradation and indicate that antioxidants can prevent matrix degradation and therefore may have a preventive or therapeutic value in arthritis. The enhancement of oxidative activity in chondrocytes and its damaging effect on matrix may be an important mechanism of matrix degradation in osteoarthritis.
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PMID:Aggrecan degradation in chondrocytes is mediated by reactive oxygen species and protected by antioxidants. 1034 32