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Query: UNIPROT:P04040 (Catalase)
 3,577 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Oxidation of methanol, formaldehyde and formic acid was studied in cells and cell-free extract of the yeast Candida boidinii No. 11Bh. Methanol oxidase, an enzyme oxidizing methanol to formaldehyde, was formed inducibly after the addition of methanol to yeast cells. The oxidation of methanol by cell-free extract was dependent on the presence of oxygen and independent of any addition of nicotine-amide nucleotides. Temperature optimum for the oxidation of methanol to formaldehyde was 35 degrees C, pH optimum was 8.5. The Km for methanol was 0.8mM. The cell-free extract exhibited a broad substrate specificity towards primary alcohols (C1--C6). The activity of methanol oxidase was not inhibited by 1mM KCN, EDTA or monoiodoacetic acid. The strongest inhibitory action was exerted by p-chloromercuribenzoate. Both the cells and the cell-free extract contained catalase which participated in the oxidation of methanol to formaldehyde; the enzyme was constitutively formed by the yeast. The pH optimum for the degradation of H2O2 was in the same range as the optimum for methanol oxidation, viz. at 8.5. Catalase was more resistant to high pH than methanol oxidase. The cell-free extract contained also GSH-dependent NAD-formaldehyde dehydrogenase with Km = 0.29mM and NAD-formate dehydrogenase with Km = 55mM.
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PMID:Studies on methanol - oxidizing yeast. III. Enzyme. 24 Jul 64

Changes in the membranes of human red cells similar to those of certain hemolytic anemias were produced by calcium in three model systems and found to result from membrane adsorption of cytosol proteins and from proteolysis. Proteins of the cytosol adsorbed to human erythrocyte membranes in the presence of calcium and extractable by EDTA were compared to those of the total cytosol by polyacrylamide gel electrophoresis and by isoelectric focusing. Catalase (EC 1.11.1.6) and band 8 were adsorbed to the membranes from the supernatant cytosol with calcium. Band 8 was a normal constitutent of the cytosol, apparently a single chain of molecular weight 24,000 with a pI of 5.35. Other calcium-induced membrane changes could be demonstrated to be due to cytosol protease(s) adsorbed to the membrane in the presence of calcium and extractable with EDTA. When membranes were incubated with the proteases and calcium the decrease in bands 1,2,3 and 4.1 and the appearance of multiple low molecular weight peptides typical of calcium-induced membrane effects resulted.
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PMID:Calcium-induced erythrocyte membrane changes. The role of adsorption of cytosol proteins and proteases. 42 45

Purified hyaluronic acid of ox vitreous humour was isolated treating the acetone precipitate of a vitreous humour homogenate with 1 M NaCl solution and thereafter with cetylpyridiniumchloride. Both disc-electrophoresis and hydroxyproline content proved the absence of collagen in the purified hyaluronic acid. FeSO4, ascorbate, and cysteine changed the hyaluronic acid molecule and lowered the viscosity of the hyaluronic acid solution, EDTA alone did not affect the viscosity but enhanced the effectiveness of iron ions or ascorbate on the viscosity of the solution. Catalase prevented the reduction of the viscosity by the above mentioned substances. Therefore, it is suggested that H2O2 and free radicals are generated during the reaction. The free radicals produced are responsible for the change of the hyaluronic acid molecule.
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PMID:[The change of hyaluronic acid of the vitreous humour by oxidation-reduction-systems (author's transl)]. 82 40

Site-specific and random fragmentation of human Cu,Zn-superoxide dismutase (Cu,Zn-SOD) was observed following the glycation reaction (the early stage of the Maillard reaction). The fragmentation proceeded in two steps. In the first step, Cu,Zn-SOD was cleaved at a peptide bond between Pro62 and His63, as judged by amino acid analysis and sequencing of fragment peptides, yielding a large (15 kDa) and a small (5 kDa) fragment. In the second step, random fragmentation occurred. The ESR spectrum of the glycated Cu,Zn-SOD suggested that reactive oxygen species was implicated in the both steps of fragmentation. The same fragmentations were seen upon exposure of the enzyme to an H2O2 bolus. Catalase completely blocked both steps of the fragmentation process, whereas EDTA blocked only the second step. Incubation with glucose resulted in a time-dependent release of Cu2+ from the Cu,Zn-SOD molecule. The released Cu2+ then likely participated in a Fenton's type of reaction to produce hydroxyl radical, which may cause the nonspecific fragmentation. Evidence that EDTA abolished only the second step of fragmentation induced by an H2O2 bolus supports this mechanism. This is the first report that a site-specific fragmentation of a protein is caused by reactive oxygen species formed by the Maillard reaction.
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PMID:Site-specific and random fragmentation of Cu,Zn-superoxide dismutase by glycation reaction. Implication of reactive oxygen species. 132 27

Neutrophils activated by soluble particulate stimuli generate superoxide anion and subsequently form hydrogen peroxide and other oxygen radicals. The effect of hydrogen peroxide on the complement system in normal serum was investigated. Treatment of normal serum with hydrogen peroxide resulted in a diminution of the haemolytic activity of the total and alternative complement pathways and the haemolytic titres of C3 and C5 but not of C2, in normal serum. These decreases in complement activity depended on the concentration of hydrogen peroxide added to the serum. Immunoelectrophoretic analysis of hydrogen peroxide-treated serum showed that C3 and C5 proteins were activated. Complement degradation products C3a and C5a were produced in normal serum treated with hydrogen peroxide, and 20 mM EDTA abolished C3a and C5a production in hydrogen peroxide-treated serum but 20 mM Mg-EGTA did not. Catalase completely abolished and dimethylsulphoxide and D-mannitol, hydroxyl radical scavengers, partially inhibited the hydrogen peroxide-mediated complement activation. Hypochlorite, incubated with normal serum, significantly inhibited serum haemolytic activity, and sodium thiosulphate, a reducing agent, abolished the effect of hypochlorite. Normal serum incubated with activated neutrophils showed neutrophil chemotactic activity and decreased serum haemolytic activity, and the addition of catalase or methionine (5 mM) completely abolished the effects of activated neutrophils. These results suggest that hydrogen peroxide activates complement via an alternative pathway of complement activation and that hydroxyl radicals and other hydrogen peroxide-related species such as hypochlorite are most likely involved in hydrogen peroxide-mediated complement activation. Complement activation by oxygen radicals produced by activated neutrophils may be one of the mechanisms by which complement is activated in human immune complex diseases.
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PMID:Activation of complement in normal serum by hydrogen peroxide and hydrogen peroxide-related oxygen radicals produced by activated neutrophils. 132 92

Rifamycins are antibacterial antibiotics which are especially useful for the treatment of tuberculosis. Reactive oxygen intermediates are produced in the presence of rifamycin SV and metals such as copper or manganese. Experiments were carried out to evaluate the interaction of rifamycin SV with rat liver microsomes to catalyze the production of reactive oxygen species. At a concentration of 1 mM, rifamycin SV increased microsomal production of superoxide with NADPH as cofactor 3-fold, and with NADH as reductant by more than 5-fold. Rifamycin SV increased rates of H2O2 production by the microsomes twofold with NADPH, and 4- to 8-fold with NADH. In the presence of various iron complexes, microsomes generated hydroxyl radical-like (.OH) species. Rifamycin SV had no effect on NADPH-dependent microsomal .OH production, irrespective of the iron chelate. A striking stimulation of .OH production was found with NADH as the reductant, ranging from 2- to 4-fold with catalyst such as ferric-EDTA and ferric-DTPA to more than 10-fold with ferric-ATP, -citrate, or -histidine. Catalase and competitive .OH scavengers lowered rates of .OH production (chemical scavenger oxidation) and prevented the stimulation by rifamycin. Superoxide dismutase had no effect on the NADH-dependent rifamycin stimulation of .OH production with ferric-EDTA or -DTPA, but was inhibitory with the other ferric complexes. In contrast to the stimulatory effects on production of O2-., H2O2, and .OH, rifamycin SV was a potent inhibitor of microsomal lipid peroxidation. These results show that rifamycin SV stimulates microsomal production of reactive oxygen intermediates, and in contrast to results with other redox cycling agents, is especially effective with NADH as the microsomal reductant. These interactions may contribute to the hepatotoxicity associated with use of rifamycin, and, since alcohol metabolism increases NADH availability, play a role in the elevated toxic actions of rifamycin plus alcohol.
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PMID:Stimulation of microsomal production of reactive oxygen intermediates by rifamycin SV: effect of ferric complexes and comparisons between NADPH and NADH. 132 62

Oxidative damage to bovine serum albumin (BSA) was induced by hydroxyl radical (HO.) generating systems of xanthine oxidase (XO) + EDTA-Fe3+ and ascorbate + EDTA-Fe3+. Formation of bityrosine and loss of tryptophan were observed in the ascorbate + EDTA-Fe3+ system and carbonyl formation was induced by both systems. Mannitol and ethanol very strongly inhibited the carbonyl and/or bityrosine formation, indicating that the oxidative damage to BSA was due to HO(.). The sulfhydryl (SH) groups of BSA were very sensitive to the XO + EDTA-Fe3+ but not to the ascorbate + EDTA-Fe3+ system. Catalase but not hydroxyl radical scavengers or superoxide dismutase strongly inhibited the loss of SH groups, indicating that H2O2 is involved in their oxidation. Fragmentation of BSA was observed during exposure to the XO + EDTA-Fe3+ and ascorbate + EDTA-Fe3+ systems and the products presented a broad band on sodium dodecyl sulfate polyacrylamide gel electrophoresis. Little formation of amine groups was observed in these systems, indicating that little peptide bond cleavage occurred. BSA exposed to the ascorbate + EDTA-Fe3+ system was more readily degraded by trypsin than that exposed to the XO + EDTA-Fe3+ system. Elastase degraded BSA exposed to the ascorbate + EDTA-Fe3+ system but not to the XO + EDTA-Fe3+ system.
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PMID:Oxidative damage to bovine serum albumin induced by hydroxyl radical generating systems of xanthine oxidase + EDTA-Fe3+ and ascorbate + EDTA-Fe3+. 133 12

1. The hydroxyl radical-mediated conversion of morphine to morphinone (MO) was examined as an alternative to the enzymic reaction. 2. Hydroxyl radicals were generated by autoxidation of ascorbate in the presence of iron and EDTA. This system oxidized morphine to MO which was identified by h.p.l.c. and t.l.c. The reaction was dependent on the concentration of added Fe2+ and required the addition of ascorbate when Fe3+ was used. 3. Catalase inhibited production of MO whereas superoxide dismutase (SOD) had no effect. Addition of a large amount of H2O2 to the system resulted in a significant decrease in production of MO. No MO production was initiated by H2O2 itself. The oxidation of morphine was inhibited by typical hydroxyl radical-scavenging agents. These results indicate that morphine undergoes oxidation to MO by hydroxyl radical.
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PMID:Hydroxyl radical-mediated conversion of morphine to morphinone. 138 46

The oxidative demethylenation reactions of (methylendioxy)phenyl compounds (MDPs), (methylenedioxy)benzene (MDB), (methylenedioxy)amphetamine (MDA), and (methylenedioxy)methamphetamine (MDMA), were evaluated by using two hydroxyl radical generating systems, the autoxidation of ascorbate in the presence of iron-EDTA and the iron-catalyzed Haber-Weiss reaction conducted by xanthine/xanthine oxidase with iron-EDTA. Reaction products generated when MDB, MDA, and MDMA were incubated with the ascorbate or xanthine oxidase system were catechol, dihydroxyamphetamine (DHA), and dihydroxymethamphetamine (DHMA), respectively. The reaction required the presence of either ascorbic acid or xanthine oxidase. Levels of each catechol increased in proportion to ferric ion concentration and were suppressed by desferrioxamine B methanesulfonate (desferal). Catalase (CAT) inhibited the oxidation by the ascorbate system whereas superoxide dismutase (SOD) had little effect. The addition of hydrogen peroxide to the reaction mixture stimulated the oxidation, but the reaction was not initiated by hydrogen peroxide alone, suggesting that hydrogen peroxide acts as a precursor of hydroxyl radical. SOD and CAT suppressed the demethylenation reactions in the xanthine oxidase system. Hydroxyl radical scavenging agents such as ethanol, benzoate, DMSO, and thiourea effectively inhibited the oxidation by both systems. Urea, which has little effect on hydroxyl radical, was without any effect. These results indicated that hydroxyl radical can effect the cleavage of methylenedioxy group on MDPs.
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PMID:Hydroxyl radical mediated demethylenation of (methylenedioxy)phenyl compounds. 168 Apr 77

The effect of oxygen derived free radicals (ODFR) upon the specific viscosity of equine synovial fluid was studied. ODFR were generated either by a mixture of ferrous iron and EDTA (Fe/EDTA) or by a mixture of hypoxanthine and xanthine oxidase (HX/XO). Incubation of the synovial fluid with both free radical generating systems decreased its specific viscosity. When the synovial fluid was incubated with Fe/EDTA the specific viscosity of the synovial fluid was reduced rapidly. By 2 mins, it was 53 +/- 3 per cent of the original specific viscosity and by 30 mins it was reduced to 39 +/- 5 per cent. In the HX/XO system, the specific viscosity was 75 +/- 4 per cent of the original specific viscosity at 10 mins and by 50 mins it was reduced to 55 +/- 3 per cent. Palosein (superoxide dismutase) was an effective inhibitor of the free radical induced reduction of the viscosity of the synovial fluid when the free radicals were generated with HX/XO but not with Fe/EDTA. Catalase was moderately effective as an inhibitor of reduction in specific viscosity of the synovial fluid when the free radicals were generated by either system. Only minor synergy resulted when mixtures of Palosein and catalase were tested for inhibition of Fe/EDTA induced reduction in the specific viscosity of equine synovial fluid. The results indicate that Palosein may protect equine synovial fluid from the effects of the superoxide radical (O2-) but not from the hydroxyl radical (OH.).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of palosein (superoxide dismutase) and catalase upon oxygen derived free radical induced degradation of equine synovial fluid. 229 85


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