Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.15.1.1 (superoxide dismutase)
58,858 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The air oxidation of procarbazine in the presence of Ti(IV) was examined as a model system for the effects titanium has on oxidative processes and intermediates involving molecular oxygen. It was found that Ti(IV) inhibited oxidation when the substrate, procarbazine, was coordinated to titanium. This inhibition was most prominent (reduction of overall rate constant by a factor of 10(2)) in its interference with Cu(II) catalyzed oxidation of the substrate whole oxidation by the neutral species O2 was only slightly inhibited (factor of 2). However, when Mn(II) was used to catalyze the oxidation of procarbazine by air, titanium enhanced the catalytic effect of Mn(II) by a factor of 10(2). This enhancement was found to be due to Ti(IV) catalysis of the air oxidation of Mn(II), and the effect was found to be inhibited by catalase but not superoxide dismutase or peroxidase. These results are discussed in terms of a Ti(IV) ability to activate molecular oxygen and its ability to form oxygen free-radical complexes.
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PMID:Oxidation of procarbazine in the presence of Ti(IV). 1 28

Eosinophil and/or neutrophil leukocytes appear to have important roles in host defense against invasive, migratory helminth infestations, but the mechanisms of larval killing by leukocytes are uncertain. This study examines killing of newborn (migratory phase) larvae of Trichinella spiralis during incubation with granule preparations of human eosinophils or neutrophils and generators of hydrogen peroxide (glucose-glucose oxidase) (G-GO) or superoxide and hydrogen peroxide (xanthine-xanthine oxidase). Larvae were killed by either hydrogen peroxide-generating system in a concentration-dependent manner. Direct enumeration of surviving larvae after incubation in microtiter wells containing the appropriate reagents was used in assess larval killing. Verification of the microplate assay was demonstrated by complete loss of larval ability to incorporate [(3)H]deoxyglucose and loss of infectivity after incubation in comparable concentrations of G-GO. Larvae were highly sensitive to oxidative products; significant killing occurred after incubation with 0.12 mU glucose oxidase and complete killing occurred with 0.5 mU. Comparable killing of bacteria required over 60 mU glucose oxidase. At 5 mU glucose oxidase, killing was complete after 6 h of incubation. Killing by G-GO was inhibited by catalase but not by boiled catalase or superoxide dismutase and was enhanced by azide. Addition of peroxidase in granule pellet preparations of eosinophils or neutrophils did not enhance killing by G-GO. These data indicate a remarkable susceptibility of newborn larvae of T. spiralis to the hydrogen peroxide generated by neutrophil and eosinophil leukocytes.
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PMID:Mechanisms of killing of newborn larvae of Trichinella spiralis by neutrophils and eosinophils. Killing by generators of hydrogen peroxide in vitro. 4 Oct 2

A sensitive method for evaluating extracellular parasite viability was used to determine the in vitro susceptibility of virulent Toxoplasma gondii to selected oxygen intermediates. By acridine orange fluorescent staining criteria, toxoplasmas were resistant to up to either 10(-3) M reagent H2O2 or H2O2 generated by glucose-glucose oxidase. In keeping with a lack of sensitivity to H2O2, toxoplasmas contained endogenous catalase (5.7 x 10(-4) Baudhuin units/10(6) organisms). The addition of a peroxidase and halide, however, markedly accelerated killing and lowered the H2O2 requirement by 1,000-fold. In contrast, toxoplasmas were promptly killed after exposure to products generated by xanthine (1.5 x 10(-4) M) and xanthine oxidase (50 micrograms). The inhibition of this system's microbicidal activity by scavengers of O2- (superoxide dismutase) and H2O2 (catalase) indicated that although neither O2- nor H2O2 were toxoplasmacidal, their interaction was required for parasite killing. Quenching OH. and 1O2, presumed products of O2--H2O2 interaction, by mannitol, benzoate, diazabicyclooctane, and histidine, also inhibited toxoplasma killing by xanthine-xanthine oxidase. These findings suggested that O2- and H2O2 functioned in precursor roles and that OH. and 1O2 were toxoplasmacidal. The capacity of normal peritoneal macrophages to pinocytose an oxygen intermediate scavenger, soluble catalase, was also demonstrated. Appreciable extraphagosomal concentrations of catalase were achieved by exposing macrophages to 1 mg/ml of the enzyme for 3 h. Maintenance of high intracellular levels required constant exposure because interiorized catalase was rapidly degraded.
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PMID:Macrophage oxygen-dependent antimicrobial activity. I. Susceptibility of Toxoplasma gondii to oxygen intermediates. 9 21

1. Dihydroxyfumarate slowly autoxidizes at pH6. This reaction is inhibited by superoxide dismutase but not by EDTA. Mn2+ catalyses dihydroxyfumarate oxidation by reacting with O2 leads to to form Mn3+, which seems to oxidize dihydrofumarate rapidly. Cu2+ also catalyses dihydroxyfumarate oxidation, but by a mechanism that does not involve O2 leads to. 2. Peroxidase catalyses oxidation of dihydroxyfumarate at pH6; addition of H2O2 does not increase the rate. Experiments with superoxide dismutase and catalase suggest that there are two types of oxidation taking place: an enzymic, H2O2-dependent oxidation of dihydroxyfumarate by peroxidase, and a non-enzymic reaction involving oxidation of dihydroxyfumarate by O2 leads to. The latter accounts for most of the observed oxidation of dihydroxyfumarate. 3. During dihydroxyfumarate oxidation, most peroxidase is present as compound III, and the enzymic oxidation may be limited by the low rate of breakdown of this compound. 4. Addition of p-coumaric acid to the peroxidase/dihydroxyfumarate system increases the rate of dihydroxyfumarate oxidation, which is now stimulated by addition of H2O2, and is more sensitive to inhibition by catalase but less sensitive to superoxide dismutase. Compound III is decomposed in the presence of p-coumaric acid. p-Hydroxybenzoate has similar, but much smaller, effects on dihydroxyfumarate oxidation. However, salicylate affects neither the rate nor the mechanism of dihydroxyfumarate oxidation. 5. p-Hydroxybenzoate, salicylate and p-coumarate are hydroxylated by the peroxidase/dihydroxyfumarate system. Experiments using scavengers of hydroxyl radicals shown that OH is required. Ability to increase dihydroxyfumarate oxidation is not necessary for hydroxylation to occur.
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PMID:Generation of hydrogen peroxide, superoxide and hydroxyl radicals during the oxidation of dihydroxyfumaric acid by peroxidase. 19 74

Gossipol oxidation with peroxidase accompanied by chemiluminescence is revealed. Effect of some factors on chemiluminescence is investigated. Peroxidase gossipol oxidation is suggested to be one of the causes of spontaneous cotton root luminescence. Chemiluminescence in the system studied is inhibited by superoxide dismutase, which indicates the generation of superoxide anion radical. It is suggested that these radicals and other activated oxygen species are involved in the gossipol toxicity for parasitic microorganisms.
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PMID:[Chemiluminescence during oxidation of gossipol by peroxidase]. 21 69

A general consideration of the pathogenesis of the various metabolic diseases which produce mental deficiency suggests that perturbation of the one carbon (folate) cycle may be important. Secondly, a review of diseases having some symptoms in common with trisomy 21 suggests the evidence of : a collagen disturbance (hypothyroidism and iminodipeptidurial) ; an oxygen disturbance (hypothyroidism and hemoglobinopathies) ; a cholinergic distrubance (Alzheimer's disease) ; a one-carbon-cycle disturbance (Lesch-Nyhan's disease). Thirdly, the peculiar pathology of trisomy 21 allows to find also a cholinergic disturbance and a disturbance close to the 10 formyl-tetrahydrololate entry of the folate cycle. Finally, an analysis of the possible effect of the excess of superoxide dismutase A and of the increase of glutathion peroxidase leads to the suspicion that a difficulty exists of dioxygenations and of non aromatic hydroxilations with a relative retardation of some FAD requiring reactions. A simplified scheme shows that these metabolic deviations could provoke a disturbance of the collagen and of synthesis of chemical mediators, in accordance with the indications furnished by the compared pathogenesis of the various affections studied. These heuristic reflexions open the way to further investigations.
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PMID:[Biochemical investigations and trisomy 21 (author's transl)]. 22 17

Oxygen-intolerant mutants of Escherichia coli K12 were selected by a replica plating technique after treatment with the mutagen, N-methyl-N'-nitro-N-nitrosoguanidine, to a lethality of 99.5%. One group of mutants had lost the ability to induce both peroxidase and catalase when exposed to oxygen but retained the ability to induce the manganese-superoxide dismutase. The second group of mutants had lost the ability to induce the activity of all these enzymes. Failure to induce peroxidase and catalase was associated with enhanced susceptibility of the bacteria to the lethal effect of oxygen. When a member of the first group of mutants was prevented from producing the manganese-superoxide dismutase by the presence of puromycin, its susceptibility to the lethal effects of oxygen was greatly increased. Two types of revertants were seen. In one group the ability to induce enzyme activity was recovered and was accompanied by the return of oxygen tolerance. Members of the other group lost the ability to respire and, therefore, no longer produced O2- AND H2O2. These results indicated that enzymic scavenging of both H2O2 and O2- provides an important defense against oxygen toxicity. The parallel loss of peroxidase and catalase, which was seen in all mutants, suggests that these enzymes constitute a precursor-product pair in E. coli. The parallel loss in two of these mutants of peroxidase, catalase, and the manganese-superoxide dismutase suggests a control linkage for these enzymes, the basis of which remains to be explored.
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PMID:Superoxide, hydrogen peroxide, and oxygen tolerance of oxygen-sensitive mutants of Escherichia coli. 23 37

Conditions for continuous culture of Escherichia coli K-12 His- Thi- under glucose limitation were established. Both the capacity for respiration, at D greater than 0.2/h, and specific activity of superoxide dismutase increased as a function of specific growth rate, whereas peroxidase and catalase were either invariant with or inversely related to this growth rate. The abrupt increase in the availability of glucose, as a means of elevating the growth rate, was followed by an increase in superoxide dismutase, which reached a plateau before there was a significant increase in the growth rate. Thus, an increase in superoxide dismutase appeared to be a prerequisite for an increase in the rate of growth. Cells that had higher levels of superoxide dismutase, because of varying specific growth rates, were more resistant to the toxicity of hyperbaric oxygen. Superoxide dismutase thus behaved like an essential defense against the toxicity of oxygen. Sensitivity towards streptonigrin increased with specific growth rate in the range of 0.09 to 0.25/h but decreased with further increases in the growth rate. Since this antibiotic has been shown to shunt electrons to oxygen, with concomitant production of O2-, these results indicated a progressive deficiency of reducing power at growth rates below 0.25/h and a surfeit of reducing power with progressively greater protection against O2- by superoxide dismutase at growth rates greater than 0.25/h.
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PMID:Physiological function of superoxide dismutase in glucose-limited chemostat cultures of Escherichia coli. 23 20

Anaerobically grown Escherichia coli K-12 contain only one superoxide dismutase and that is the iron-containing isozyme found in the periplasmic space. Exposure to oxygen caused the induction of a manganese-containing superoxide dismutase and of another, previously undescribed, superoxide dismutase, as well as of catalase and peroxidase. These inductions differed in their responsiveness towards oxygen. Thus the very low levels of oxygen present in deep, static, aerobic cultures were enough for nearly maximal induction of the manganese-superoxide dismutase. In contrast, induction of the new superoxide dismutase, catalase, and peroxidase required the much higher levels of oxygen achieved in vigorously agitated aerobic cultures. Anaerobically grown cells showed a much greater oxygen enhancement of the lethality of streptonigrin than did aerobically grown cells, in accord with the proposal that streptonigrin can serve as an intracellular source of superoxide. Anaerobically grown cells in which enzyme inductions were prevented by puromycin were damaged by exposure to air. This damage was evidenced both as a decline in viable cell count and as structural abnormalities evident under an electron microscope.
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PMID:Enzymatic defenses against the toxicity of oxygen and of streptonigrin in Escherichia coli. 32 33

The activities of various peroxide-metabolizing enzymes were determined in homogenates of human liver excisions. The specific activity of selenium-dependent glutathione peroxidase was 41.1 +/- 23.7 (S.D.) mU/mg protein; non-selenium glutathione peroxidase showed a activity of 30.5 +/- 14.0 mU/mg protein. The catalase and superoxide dismutase concentrations were 4.72 +/- 0.58 and 1.87 +/- 0.68 microgram/mg protein, respectively. Total glutathione amounted to 12.9 +/- 7.4 nmol/mg. Malondialdehyde formation, used as the basis for the determination of lipid hydroperoxides, was 0.32 +/- 0.14 nmol/mg. The data indicate much lower enzyme and substrate levels compared to rats and mice. A positive correlation of r = 0.48 +/- 0.31 was found between the glutathione level and selenium-dependent peroxidase. Selenium-dependent and non-selenium-glutathione peroxidase correlate negatively (r = -0.71 +/- 0.18); superoxide dismutase concentration and lipid-hydroperoxides are also related by a negative correlation coefficient of r = 0.47 +/- 0.31. These data stress the major hepatoprotective role of these systems in human liver.
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PMID:[The activity of the peroxide-metabolizing system in human liver (author's transl)]. 45 83


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