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)

Incubation of aqueous solutions of 2-nitropropane in air causes a slow oxidation reaction that generates H(2)O(2). Purified horseradish peroxidase catalyses the oxidation of such preincubated 2-nitropropane solutions according to the equation: [Formula: see text] The pH optimum is 4.5 and K(m) for 2-nitropropane is 16mm. Other nitroalkanes or nitro-aromatics tested are not oxidized at significant rates by peroxidase. H(2)O(2) or 2,4-dichlorophenol increases the rate of 2-nitropropane oxidation by peroxidase. Catalase inhibits the reaction completely. Superoxide dismutase or mannitol, a scavenger of the hydroxyl radical, OH(.), each inhibits partially. Aniline and guaiacol are also powerful inhibitors of 2-nitropropane oxidation. It is suggested that peroxidase uses the traces of H(2)O(2) generated during preincubation of 2-nitropropane to catalyse oxidation of this substrate into a radical species that can reduce O(2) to the superoxide ion, O(2) (-.).O(2) (-.), or OH(.) derived from it, then appears to react with more nitropropane, generating further radicals and H(2)O(2) to continue the oxidation. Inhibition by aniline and guaiacol seems to be due to a competition for H(2)O(2).
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PMID:Oxidation of 2-nitropropane by horseradish peroxidase. Involvement of hydrogen peroxide and of superoxide in the reaction mechanism. 21 46

1. Haemogloblin and myoglobin enhance rat liver microsomal p-hydroxylation of aniline and acetanilide. Microsomal N-demethylation of ethylmorphine and aminopyrine is not increased by haemoproteins. 2. The enhancement of microsomal p-hydroxylation is maximal at high substrate concentration and high haeme compound concentration. 3. Detergent-purified NADPH-cytochrome c reductase, free flavins and manganese ions considerably increase the haemoglobin-mediated, tissue-free hydroxylation of aniline. Microsomal aniline hydroxylation is not enhanced by haeme, ferric ion or albumin. 4 Catalase and cyanide ions are powerful inhibitors of haemoglobin-mediated aniline hydroxylation both in the presence and absence of tissue. Carbon monoxide inhibits the hydroxylase activity of the tissue-free system to a smaller extent than that of a system containing microsomes plus haemoglobin whereas p-chloromercuribenzoate inhibits only the flavoprotein-dependent hydroxylation of aniline mediated by haemoglobin. 5. Several possibilities of interactions between substrate, microsomes and haeme compounds are proposed.
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PMID:Enhancement of microsomal aniline and acetanilide hydroxylation by haemoglobin. 82 88

Human hemoglobin was characterized as an enzyme in a reconstituted aniline hydroxylase system containing hemoglobin, NADPH, rat liver cytochrome P-450 reductase, aniline and atmospheric O2. This system catalyzed p-aminophenol formation (turnover number 0.2 mol/min/mol of hemoglobin) with an efficiency similar to that which has been reported for either microsomal cytochrome P-450 or cytochrome P-450 solubilized from rat liver. The rate of the reaction was linearly dependent on hemoglobin concentration up to approximately 1 nmol of hemoglobin/ml. This linear range of hemoenzyme concentration is also similar to cytochrome P-450-catalyzed reactions. Unlike the cytochrome P-450 system, the hemoglobin system did not require a lipid cofactor for maximal activity, and much less reductase was needed for maximal activity. Aniline displayed typical Michaelis-Menten saturation kinetics as substrate, and its Km (8 mM) was the same in the absence of presence of the reductase. Catalase essentially completely inhibited p-aminophenol formation in the absence or presence of reductase. In contrast, superoxide dismutase inhibited the reductase-mediated reaction only to a small extent (if at all). No detectable hydrogen peroxide accumulated during the course of the reaction in the absence of catalase. These findings suggested a hypothetical mechanism for hemoglobin-catalyzed hydroxylation of aniline involving a hemoglobin-bound form of hydrogen peroxide (aniline-Hb3+-OOH-) as an intermediate preceding the rate-determining formation of products.
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PMID:Characterization of Enzyme-like activity of human hemoglobin. Properties of the hemoglobin-P-450 reductase-coupled aniline hydroxylase system. 93 94

Glucose oxidase (GOD) was immobilized on agrose(a) by diazotization using p(beta-sulfate-ethylfonyl)aniline(SESA) as cross-linking agent, (b) by a new improved glutaraldehyde method and (c) by polyacrylamide entrapment. Results showed that GOD immobilized by the improved glutaraldehyde method had an activity of 10% and 100% higher than that by diazotization and entrapment method respectively. Catalase co-immobilized with GOD on agrose greatly enhanced the stability of GOD. Proteins such as hemoglobin(Hb), bovine serum albumin(BSA) and reducing agent i.e. VitC added during immobilization had the same effect but to a lesser extent.
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PMID:Reactivity and stability improvement of immobilized glucose oxidase. 250 74

Norharman (9H-pyrido[3,4-b]indole), which is a heterocyclic amine included in cigarette smoke or cooked foodstuffs, is not mutagenic itself. However, norharman reacts with non-mutagenic aniline to form mutagenic aminophenylnorharman (APNH), of which DNA adducts formation and hepatocarcinogenic potential are pointed out. We investigated whether N-OH-APNH, an N-hydroxy metabolite of APNH, can cause oxidative DNA damage or not, using 32P-labeled DNA fragments. N-OH-APNH caused Cu(II)-mediated DNA damage. When an endogenous reductant, beta-nicotinamide adenine dinucleotide (NADH) was added, the DNA damage was greatly enhanced. Catalase and a Cu(I)-specific chelator inhibited DNA damage, suggesting the involvement of H(2)O(2) and Cu(I). Typical -*OH scavenger did not inhibit DNA damage. These results suggest that the main reactive species are probably copper-hydroperoxo complexes with DNA. We also measured 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) formation by N-OH-APNH in the presence of Cu(II), using an electrochemical detector coupled to a high-pressure liquid chromatograph. Addition of NADH greatly enhanced 8-oxodG formation. UV-VIS spectra and mass spectra suggested that N-OH-APNH was autoxidized to nitrosophenylnorharman (NO-PNH). We speculated that NO-PNH was reduced by NADH. Cu(II) facilitated the redox cycle. In the presence of NADH and Cu(II), very low concentrations of N-OH-APNH could induce DNA damage via redox reactions. We conclude that oxidative DNA damage, in addition to DNA adduct formation, may play an important role in the expression of genotoxicity of APNH.
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PMID:Oxidative DNA damage by an N-hydroxy metabolite of the mutagenic compound formed from norharman and aniline. 1142 46

Catalase-peroxidases (KatGs) are prokaryotic heme peroxidases with homology to yeast cytochrome c peroxidase (CCP) and plant ascorbate peroxidases (APXs). KatGs, CCP and APXs contain identical amino acid triads in the heme pocket (distal Arg/Trp/His and proximal His/Trp/Asp), but differ dramatically in their reactivities towards hydrogen peroxide and various one-electron donors. Only KatGs have high catalase activity in addition to a peroxidase activity of broad specificity. Here, we investigated the effect of mutating the conserved proximal triad on KatG catalysis. With the exception of W341F, all variants (H290Q, W341A, D402N, D402E) exhibited a catalase activity <1% of wild-type KatG and spectral properties indicating alterations in heme coordination and spin states. Generally, the peroxidase activity was much less effected by these mutations. Compared with wild-type KatG the W341F variant had a catalase and halogenation activity of about 40% and an even increased overall peroxidase activity. This variant, for the first time, allowed to monitor the hydrogen peroxide mediated transitions of ferric KatG to compound I and back to the resting enzyme. Compound I reduction by aromatic one-electron donors (o-dianisidine, pyrogallol, aniline) was not influenced by exchanging Trp by Phe. The findings are discussed in comparison with the data known from CCP and APX and a reaction mechanism for the multifunctional activity of the W341F variant is suggested.
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PMID:Engineering the proximal heme cavity of catalase-peroxidase. 1212 64

Conjugated polymers are attractive for many applications due to their unique properties. Their molecular structure can easily be tuned, making them suitable for an enormous number of specific applications. Conjugated polymers have the potential to achieve electrical properties similar to those of noncrystalline inorganic semiconductors; however, their chemical structure is much more complex and somewhat resembles that of biomacromolecules. The molecular conformation and interactions of conjugated polymers play an important role in their functionality. The use of enzymes has emerged as a highly valuable alternative method to synthesize these polymers and is very useful in the fabrication of their nanostructures. Here, we present established strategies for the synthesis of conjugated polymers in template-free systems that do not interfere with the preparation of their nanostructures. These strategies are based on the use of peroxidases (class III; EC 1.11.1.7, donor: hydrogen peroxide oxidoreductase), which are enzymes that have the ability to catalyze the oxidation of a number of compounds (including aromatics such as aniline, pyrrole, thiophene and some of their derivatives), in the presence of hydrogen peroxide, to obtain conjugated polymers.
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PMID:Radical addition polymerization: Enzymatic template-free synthesis of conjugated polymers and their nanostructure fabrication. 3163 Jul 46