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)

We partially purified a preparation from Escherichia coli that proteolytically degrades the enzyme glutamine synthetase [L-glutamate:ammonia ligase (ADP-forming), EC 6.3.1.2]. The degradation is at least a two-step process. First, the glutamine synthetase undergoes an oxidative modification. This modification leads to loss of catalytic activity and also renders the protein susceptible to proteolytic attack in the second step. The oxidative step displays characteristics of a mixed-function oxidation, requiring both molecular oxygen and a reduced nucleotide. This step can also be catalyzed by a purified, mammalian cytochrome P-450 system, as well as by a model system consisting of ascorbic acid and oxygen. Catalase blocks this oxidative modification step. Thus, the overall process of proteolytic degradation can be observed only if care is taken to remove catalase activity from the extracts. The inactivation reaction is dependent on the state of adenylylation of the glutamine synthetase, suggesting that this a physiologically important reaction. If so, then mixed-function oxidases are now implicated in the process of intracellular protein turnover.
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PMID:Turnover of bacterial glutamine synthetase: oxidative inactivation precedes proteolysis. 611 90

NADPH-quinone reductase catalyzes the two-electron reduction of quinones such as menadione, and generally is considered to play a protective role against quinone-mediated toxicity. Recent studies have shown that reactive oxygen intermediates may be produced during metabolism of quinones by quinone reductase. Experiments were carried out to evaluate the effect of iron complexes on production of hydroxyl radical (.OH) when menadione was oxidized by a rat liver cytosolic fraction. Menadione-stimulated H2O2 production when added to the cytosol; dicoumarol, a potent inhibitor of quinone reductase, completely blocked this stimulation. Results were identical with either NADH or NADPH as reductant. In the absence of added iron, .OH, assessed as oxidation of chemical scavengers, was not produced. Various ferric chelates, added to the cytosol in the absence of menadione, did not catalyze .OH production. However, .OH was produced in the presence of menadione with all ferric complexes evaluated except for ferric-desferrioxamine. Catalase, competitive scavengers and GSH inhibited .OH production, as did dicoumarol. Superoxide dismutase inhibited with ferric-ATP, ferric-citrate, ferric-histidine or ferric ammonium sulfate as iron catalysts, but had no effect with ferric-EDTA or ferric-diethylenetriamine penta-acetic acid. Reduction of the ferric complexes was increased by menadione. NADH and NADPH were equally effective as cofactor for all these reactions. Metabolism of menadione in the presence of iron complexes caused inactivation of enzymes present in the cytosolic fraction such as glutamine synthetase and lactic dehydrogenase. These results indicate that metabolism of menadione by quinone reductase can lead to the production of .OH in the presence of various ferric catalysts.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Requirement for iron for the production of hydroxyl radicals by rat liver quinone reductase. 769 Apr

The inactivation of glutamine synthetase (GS; EC 6.3.1.2) by metal-catalyzed oxidation (MCO) systems was studied in several Prochlorococcus strains, including the axenic PCC 9511. GS was inactivated in the presence of various oxidative systems, either enzymatic (as NAD(P)H+NAD(P)H-oxidase+Fe(3+)+O(2)) or non-enzymatic (as ascorbate+Fe(3+)+O(2)). This process required the presence of oxygen and a metal cation, and is prevented under anaerobic conditions. Catalase and peroxidase, but not superoxide dismutase, effectively protected the enzyme against inactivation, suggesting that hydrogen peroxide mediates this mechanism, although it is not directly responsible for the reaction. Addition of azide (an inhibitor of both catalase and peroxidase) to the MCO systems enhanced the inactivation. Different thiols induced the inactivation of the enzyme, even in the absence of added metals. However, this inactivation could not be reverted by addition of strong oxidants, as hydrogen peroxide or oxidized glutathione. After studying the effect of addition of the physiological substrates and products of GS on the inactivation mechanism, we could detect a protective effect in the case of inorganic phosphate and glutamine. Immunochemical determinations showed that the concentration of GS protein significantly decreased by effect of the MCO systems, indicating that inactivation precedes the degradation of the enzyme.
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PMID:Regulation of glutamine synthetase by metal-catalyzed oxidative modification in the marine oxyphotobacterium Prochlorococcus. 1178 30

The C4 grass Spartina alterniflora is known for its unique salt tolerance and strong preference for ammonium (NH4+) as a nitrogen (N) source. We here examined whether Spartina's unique preference for NH4+ results in improved performance under drought stress. Manipulative greenhouse experiments were carried out to measure the effects of variable water availability and inorganic N sources on plant performance (growth, photosynthesis, antioxidant, and N metabolism). Drought strongly reduced leaf number and area, plant fresh and dry weight, and photosynthetic activity on all N sources, but the reduction was most pronounced on NH4+. Indeed, the growth advantage seen on NH4+ in the absence of drought, producing nearly double the biomass compared to growth on NO3-, was entirely obliterated under both intermediate and severe drought conditions (50 and 25% field capacity, respectively). Both fresh and dry weight became indistinguishable among N sources under drought. Major markers of the antioxidant capacity of the plant, the activities of the enzymes superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase, showed higher constitutive levels on NH4+. Catalase and glutathione reductase were specifically upregulated in NH4+-fed plants with increasing drought stress. This upregulation, however, failed to protect the plants from drought stress. Nitrogen metabolism was characterized by lower constitutive levels of glutamine synthetase in NH4+-fed plants, and a rise in glutamate dehydrogenase (GDH) activity under drought, accompanied by elevated proline levels in leaves. Our results support postulates on the important role of GDH induction, and its involvement in the synthesis of compatible solutes, under abiotic stress. We show that, despite this metabolic shift, S. alterniflora's sensitivity to drought does not benefit from growth on NH4+ and that the imposition of drought stress equalizes all N-source-related growth differences observed under non-drought conditions.
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PMID:Drought stress obliterates the preference for ammonium as an N source in the C4 plant Spartina alterniflora. 2834 31

Reptiles, the most diverse taxon of terrestrial vertebrates, might be particularly vulnerable to soil pollution. Reptiles especially lizards have been rarely evaluated in ecotoxicological studies, and there is a very limited report for effects of soil pesticide contaminants on lizards. In this study, male and female lizards (Eremias argus) were exposed to Glufosinate-ammonium (GLA) and l- Glufosinate-ammonium (L-GLA) for 60 days. Slower sprint speed, higher frequency of turning back and reduced brain index were observed in treatment groups. The accumulation of GLA in the brain of lizard was higher than that of L-GLA. Moreover, the activities of neurotoxicity-related enzymes and biomarkers of oxidative stress were also investigated. In summary, the neurotoxic effects of lizards have been observed after exposure to GLA and L-GLA. Based on the result of the Integrated Biomarker Response (IBR), males were more sensitive to contaminants than females. On the other hand, the neurotoxic pathways by GLA and L-GLA triggered were slightly different: GLA mainly acted on glutamine synthetase (GS), acetylcholinesterase (AchE) and Catalase (CAT) and L-GLA aimed at AchE, Na+/K+-ATPase, Superoxide dismutase (SOD) and Malondialdehyde (MDA). In summary, the accumulation of GLA and L-GLA in lizard's brain induced neurotoxicity by altering the levels of enzymes related to nervous system and antioxidant activity and further resulted in the decrease of brain index and locomotor performance.
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PMID:Bioaccumulation, behavior changes and physiological disruptions with gender-dependent in lizards (Eremias argus) after exposure to glufosinate-ammonium and l-glufosinate-ammonium. 3096 53