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

1. Superoxide dismutase activity was present in the heterocysts and vegetative cells of Anabaena cylindrica, but was always lower in the heterocysts. 2. No qualitative differences were found in the superoxide dismutase from the two cellular types. 3. Catalase activity was also present in both cellular types. 4. Most of the NADP reductase activity, as assayed with menadione or ferredoxin as electron acceptor, was localized within the heterocysts. 5. Studies on H2 consumption showed that most of the hydrogenase activity was associated with the heterocysts. 6. The results are discussed in terms of the postulate that superoxide dismutase and catalase are involved in the protection of the proton-donating systems participating in N2 fixation and H2 metabolism of heterocysts.
 ...
PMID:Superoxide dismutase and catalase in the protection of the proton-donating systems of nitrogen fixation in the blue-green alga Anabaena cylindrica. 10 Dec 10

In photosynthetically competent chloroplasts from spinach the quantum requirements for oxygen evolution during CO2 reduction were higher, by a factor often close to 1.5, than for oxygen evolution during reduction of phosphoglycerate. Mass spectrometer experiments performed under rate-limiting light indicated that an oxygen-reducing photoreaction was responsible for the consumption of extra quanta during carbon dioxide assimilation. Uptake of 18O2 during reduction of CO2 was considerably higher than could be accounted for by oxygen consumption during glycolate formation and by the Mehler reaction of broken chloroplasts which were present in the preparations of intact chloroplasts. The oxygen reducing reaction occurring during CO2 assimilation resulted in the formation of H2O2. This was indicated by a large stimulation of CO2 reduction by catalase, but not of phosphoglycerate reduction. Catalase could be replaced as a stimulant of photosynthesis by dithiothreitol or ascorbate, compounds known to react with superoxide radicals. There was no effect of dithiothreitol and ascorbate on phosphoglycerate reduction. A main effect of superoxide radicals and/or H2O2 was shown to be at the level of phosphoglycerate formation. Evidence for electron transport of oxygen was also obtained from 14CO2 experiments. The oxidation of dihydroxyacetonephosphate during a dark period or after addition of carbonyl cyanide p-trifluoromethoxyphenyl-hydrazone in the light was studied. The results indicated a link between the chloroplast pyridine nucleotide system and oxygen. Oxygen reduction during photosynthesis under conditions where light is rate limiting is seen as important in supplying the ATP which is needed for CO2 reduction but is not provided during electron transport to NADP. A mechanism is discussed which would permit proper distribution of electrons between CO2 and oxygen during photosynthesis.
 ...
PMID:Reduction of oxygen by the electron transport chain of chloroplasts during assimilation of carbon dioxide. 119 61

The NADPH-supported enzymatic reduction of molecular oxygen by ferredoxin-ferredoxin:NADP+ oxidoreductase was investigated. The ESR spin trapping technique was employed to identify the free radical metabolites of oxygen. The spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) was used to trap and identify the oxygen-derived free radicals. [17O]Oxygen was employed to demonstrate that the oxygen-centered radicals arose from molecular oxygen. From the data, the following scheme is proposed: (Formula:see text). The formation of the free hydroxyl radical during the reduction of oxygen was demonstrated with quantitative competition experiments. The hydroxyl radical abstracted hydrogen from ethanol or formate, and the resulting scavenger-derived free radical was trapped with known rate constants. If H2O2 was added to the enzymatic reaction, a stimulation of the production of the hydroxyl radical was obtained. This stimulation was manifested in both the concentration and the rate of formation of the DMPO/hydroxyl radical adduct. Catalase was shown to inhibit formation of the hydroxyl radical adduct, further supporting the formation of hydrogen peroxide as an intermediate during the reduction of oxygen. All three components, ferredoxin, ferredoxin:NADP+ oxidoreductase, and NADPH, were required for reduction. Ferredoxin:NADP+ oxidoreductase reduces ferredoxin, which in turn is responsible for the reduction of oxygen to hydrogen peroxide and ultimately the hydroxyl radical. The effect of transition metal chelators on the DMPO/hydroxyl radical adduct concentration suggests that the reduction of chelated iron by ferredoxin is responsible for the reduction of hydrogen peroxide to the hydroxyl radical via Fenton-type chemistry.
 ...
PMID:The transition metal-mediated formation of the hydroxyl free radical during the reduction of molecular oxygen by ferredoxin-ferredoxin:NADP+ oxidoreductase. 282 73

A minor pathway for cyanamide metabolism catalyzed by catalase is responsible for the conversion of cyanamide to an inhibitor of aldehyde dehydrogenase. Catalase itself is also inhibited by cyanamide. Both the activation of cyanamide by catalase and the inhibition of catalase by cyanamide were blocked in vivo by ethanol pretreatment, suggesting that these two processes are closely linked. Like other catalase oxidation reactions, the catalase mediated activation of cyanamide was inhibited by 3-amino-1,2,4-triazole in vivo and sodium azide in vitro. The relative formation of the active cyanamide metabolite was assessed in vitro by following the loss of yeast aldehyde dehydrogenase activity with time. Inhibition of the yeast enzyme by activated cyanamide was dependent on NAD+ or NADP+, a requirement not fulfilled by NADH or NADPH. Although H2O2 inhibited yeast aldehyde dehydrogenase in vitro and cyanamide inhibited hepatic catalase in vivo, the possible in hepatic H2O2 concentration following cyanamide administration does not account for the effects of cyanamide on ethanol metabolism. While the cyanamide activating enzyme has been identified as catalase, the reaction products of this reaction and, in particular, the structure of the active metabolite involved in the inhibition of aldehyde dehydrogenase remain unknown.
 ...
PMID:Catalase mediated conversion of cyanamide to an inhibitor of aldehyde dehydrogenase. 404 Mar 75

Purified ferredoxin-(cytochrome c)-NADP+ oxidoreductase and xanthine oxidase were found to catalyse the reduction of nitrofurantoin to the free radical. Under aerobic conditions, the nitrofurantoin radical underwent autoxidation to regenerate the parent compound with the concomitant production of superoxide and eventually hydrogen peroxide. The nitrofurantoin radical was also shown to react with hydrogen peroxide to generate a highly reactive species which was capable of oxidising methionine to ethylene. This active oxygen radical appeared to be identical with the crypto-OH . radical, previously proposed as being formed from the analogous reaction of the methyl viologen radical with hydrogen peroxide [R.J. Youngman and E.F. Elstner, FEBS Lett. 129, 265 (1981)]. Catalase inhibited nitrofurantoin-dependent ethylene formation in both enzyme systems, whereas superoxide dismutase was only inhibitory in the xanthine oxidase mediated reaction. Although the primary function of the respective enzyme systems is to generate the nitrofurantoin radical, the xanthine oxidase reaction is markedly more complex than that of ferredoxin-(cytochrome c)-NADP+ oxidoreductase. The differences between the two enzyme reactions appear to be due to the endogenous autoxidation of xanthine oxidase. The aerobic activation of nitrofurantoin by xanthine oxidase involved the superoxide anion as an intermediate, whereas the nitrofuran was directly reduced by ferredoxin-(cytochrome c)-NADP+ oxidoreductase without a requirement for active oxygen species.
 ...
PMID:Mechanisms of oxygen activation by nitrofurantoin and relevance to its toxicity. 629 96

NADPH bound to each Catalase subunit was replaced by NADP+ or by the dehydrogenases inhibitor 3-amino-pyridine-adenine dinucleotide phosphate (AADP). The comparison of the three enzyme forms with respect to the capability to dismutate H2O2, or to oxidize ethanol by a peroxidation process using peroxoacetic acid, showed that the enzyme activity is approximately unchanged whatever the nucleotide bound. On the contrary, the dismutation of peroxoacetic acid drops to zero when NADPH is replaced either by the oxidized NADP+ or by the inhibitor AADP. The spectral changes induced by peroxoacetic acid at the heme Soret region indicate that the three enzyme types are quickly oxidized to Compound I [FeV(O)] and successively reduced by two monoelectron intramolecular reactions leading to Compound II [FeIV(OH)] and finally to the resting state (FeIII). Therefore NADPH bound to Catalase is not essential to catalyze peroxidation processes or H2O2 dismutation, but it is essential to prevent the enzyme denaturation and to catalyze dismutation of peroxides other than H2O2.
 ...
PMID:The function of NADPH bound to Catalase. 808 59

Catalase (hydrogen peroxide:hydrogen peroxide oxidoreductase, E.C. 1. 11.1.6) is present in most aerobic prokaryotic and eukaryotic cells. Despite a large number of studies on catalases, the only mammalian catalase structure available is that from beef liver, in which about 50% of the haem groups are degraded to bile pigments. Three different crystal forms of human erythrocyte catalase were obtained by the hanging-drop vapour-diffusion technique using PEG as precipitant. Monoclinic crystals, with space group P21 and unit-cell parameters a = 102.9, b = 140.0, c = 173.6 A and beta = 103.2 degrees, require NADP(H) in the crystallization solution. Two types of hexagonal packing, with unit-cell parameters of either a = b = 86. 9, c = 255.5 A or a = b = 90.0, c = 521.2 A, were obtained under identical crystallization conditions in the absence of NADP(H). Only one diffraction data set could be collected: this was obtained from the hexagonal crystals with the smaller c axis using synchrotron radiation, with resolution to 2.65 A. A molecular-replacement solution, determined using a modified beef-liver catalase model as a search structure, corresponds to space group P6422 and contains a single subunit in the asymmetric unit, with an estimated solvent volume of about 50%. The packing determined suggests how minor rearrangements might allow the transition between both hexagonal crystal forms and provides an explanation for the anisotropic character of the corresponding diffractions.
 ...
PMID:Crystallization and preliminary structural results of catalase from human erythrocytes. 1021 8

Methylviologen (MV) induces oxidative damages in leaves. In order to understand its mechanism we studied initial biochemical events under light in MV-fed spinach leaves. When isolated chloroplasts were illuminated in the presence of MV, both stromal and thylakoid-bound ascorbate peroxidases (APX) were inactivated rapidly at the same rates, and their inactivation was retarded by ascorbate (AsA) at higher concentrations. Since MV accelerates the photoproduction of O2- in Photosystem (PS) I and simultaneously inhibits the photoreduction of monodehydroascorbate (MDA) to AsA, the inactivation of APX was attributed to the loss of AsA and accumulation of H2O2 in the stroma. Following APX, superoxide dismutase and NADP(+)-glyceraldehyde 3-phosphate dehydrogenase, both of which are vulnerable to H2O2, were inactivated by MV plus light. Dehydroascorbate reductase, monodehydroascorbate reductase, PS II, PS I and ferredoxin-NADP(+) reductase were far less sensitive to the treatment. In the treated leaves, cytosolic APX and guaiacol-specific peroxidase were also inactivated, but slower than chloroplastic APXs were. Catalase was not inactivated. Thus the MV-induced photooxidative damages of leaves are initiated with the inactivation of chloroplastic APXs and develop via the inactivation of other H2O2-sensitive targets. The decay half-life of the MDA signal after a short illumination in the leaves, as determined by in vivo electron spin resonance spectrometry (ESR), was prolonged when the H2O2-scavenging capacity of the leaf cells was abolished by the inactivation of chloroplastic and cytosolic APXs. The measurement of MDA in leaves by ESR, therefore, allows to estimate in vivo cellular capacity to scavenge the photoproduced H2O2.
 ...
PMID:Chloroplastic ascorbate peroxidase is the primary target of methylviologen-induced photooxidative stress in spinach leaves: its relevance to monodehydroascorbate radical detected with in vivo ESR. 1124 91

Light-dependent O(2) reduction concomitant with O(2) evolution, ATP formation, and NADP reduction were determined in isolated spinach (Spinacia oleracea L. var. America) chloroplast lamellae fortified with NADP and ferredoxin. These reactions were investigated in the presence or absence of catalase, providing a tool to estimate the reduction of O(2) to H(2)O(2) (Mehler reaction) concomitant with NADP reduction. In the presence of 250 micromolar O(2), O(2) photoreduction, simultaneous with NADP photoreduction, was dependent upon light intensity, ferredoxin, Mn(2+), NADP, and the extent of coupling of phosphorylation to electron flow.In the presence of an uncoupling concentration of NH(4) (+), saturating light intensity (>500 watts/square meter), saturating ferredoxin (10 micromolarity) rate-limiting to saturating NADP (0.2-0.9 millimolarity), and Mn(2+) (50-1000 micromolarity), the maxium rates of O(2) reduction were 13-25 micromoles/milligram chlorophyll per hour, while concomitant rates of O(2) evolution and NADP reduction were 69 to 96 and 134 to 192 micromoles/milligram chlorophyll per hour, respectively. Catalase did not affect the rate of NADPH or ATP formation but decreased the NADPH:O(2) ratios from 2.3-2.8 to 1.9-2.1 in the presence of rate-limiting as well as saturating concentrations of NADP.Photosynthetic electron flow at a rate of 31 micromoles O(2) evolved/milligram chlorophyll per hour was coupled to the synthesis of 91 micromoles ATP/milligram chlorophyll per hour, while the concomitant rate of O(2) reduction was 0.6 micromoles/milligram chlorophyll per hour and was calculated to be associated with an apparent ATP formation of only 2 micromoles/milligram chlorophyll per hour. Thus, electron flow from H(2)O to O(2) did not result in ATP formation significantly above that produced during NADP reduction.
 ...
PMID:Hydrogen peroxide synthesis in isolated spinach chloroplast lamellae : an analysis of the mehler reaction in the presence of NADP reduction and ATP formation. 1666 62

Treatment of E. coli extract with iron/ascorbate preferentially inactivated NADP-isocitrate dehydrogenase without affecting glucose-6-phosphate dehydrogenase. NADP-Isocitrate dehydrogenase required divalent metals such as Mg(2+), Mn(2+ )or Fe(2+) ion. Iron/ascorbate-dependent inactivation of the enzyme was accompanied with the protein fragmentation as judged by SDS-PAGE. Catalase protecting the enzyme from the inactivation suggests that hydroxyl radical is responsible for the inactivation with fragmentation. TOF-MS analysis showed that molecular masses of the enzyme fragments were 36 and 12, and 33 and 14 kDa as minor components. Based on the amino acid sequence analyses of the fragments, cleavage sites of the enzyme were identified as Asp307-Tyr308 and Ala282-Asp283, which are presumed to be the metal-binding sites. Ferrous ion bound to the metal-binding sites of the E. coli NADP-isocitrate dehydrogenase may generate superoxide radical that forms hydrogen peroxide and further hydroxyl radical, causing inactivation with peptide cleavage of the enzyme. Oxidative inactivation of NADP-isocitrate dehydrogenase without affecting glucose 6-phosphate dehydrogenase shows only a little influence on the antioxidant activity supplying NADPH for glutathione regeneration, but may facilitate flux through the glyoxylate bypass as the biosynthetic pathway with the inhibition of the citric acid cycle under aerobic growth conditions of E. coli.
 ...
PMID:Oxidative inactivation of reduced NADP-generating enzymes in E. coli: iron-dependent inactivation with affinity cleavage of NADP-isocitrate dehydrogenase. 1689 33


1 2 Next >>