Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “OXIDASES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21Linked to original sources
PubMed1991

Ultrastructural localization of cytochrome oxidase and monoamine oxidase on microcylinders, a Long-Evans rat-specific mitochondrial inclusion.

The presence of a unique inclusion body, the microcylinder, in the intracristal space of mitochondria was previously reported in various types of cells from spotted rats of the Long-Evans strain, but was not found in cells of albino rats. The microcylinder is about 30 nm in diameter and of indefinite length, and is composed of six filamentous subunits surrounding a central one. We performed electron microscopic cytochemical studies on the cells of uriniferous tubules and the corpus striatum in normal spotted rats of the Long-Evans strain and albino rats of Wistar and Sprague-Dawley strains. On the basis of oxidative polymerization of 3, 3'-diaminobenzidine by cytochrome oxidase (CYO) an cupric ferrocyanide deposition by monoamine oxidase (MAO), microcylinders were demonstrated to exhibit activity of these enzymes. Reaction products of other mitochondrial enzymes, such as succinate dehydrogenase and lactate dehydrogenase, were not deposited on microcylinders. We conclude that microcylinders are rat strain-specific mitochondrial inclusions and consist of protein components, particularly containing the mitochondrial enzymes CYO and MAO.

Animals↗
PubMed2003

Nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase) P22 Phox C242T gene polymorphism in type 1 diabetes.

Type 1 diabetes is caused by the immune-mediated destruction of insulin-secreting pancreatic beta cells and is thought to be an autoimmune disease resulting from a complex interaction of genetic and environmental factors. In animal models of type 1 diabetes, macrophages and their products, superoxides, have central roles in the beta cell destruction, but in humans their roles remain unclear. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase produces superoxide in macrophages, and its essential component, p22 phox, is a critical enzyme for superoxide production. The C242T polymorphism in the p22 phox coding gene has been reported to be associated with reduced oxidase activity. We therefore investigated whether the p22 phox gene polymorphism affected the susceptibility to and clinical course of type 1 diabetes. We examined 287 Japanese type 1 diabetic patients and 425 unrelated nondiabetic subjects. In addition, we allocated the diabetic patients to the following three groups: (1) acute-onset type 1 diabetes with at least one autoantibody (GADA, IA-2, IAA); (2) acute-onset type 1 diabetes without autoantibodies; and (3) slow-onset type 1 diabetes with autoantibody. We could not find a significant difference in p22 phox genotype and T allele frequency between overall type 1 diabetic patients and control subjects. Regardless of the onset pattern and autoantibody positivity of type 1 diabetes, no difference in p22 phox genotype and T allele frequency was found among the groups. In conclusion, the p22 phox C242T gene polymorphism did not affect the susceptibility to and clinical course of Japanese type 1 diabetes.

Base Sequence↗
PubMed1986

Studies of monoamine oxidase and semicarbazide-sensitive amine oxidase. II. Inhibition by alpha-methylated substrate-analogue monoamines, alpha-methyltryptamine, alpha-methylbenzylamine and two enantiomers of alpha-methylbenzylamine.

The alpha-methylated substrate-analogue monoamines, dl-alpha-methyltryptamine, dl-alpha-methylbenzylamine and two optical isomers of alpha-methylbenzylamine, were shown to be inhibitors of rat lung semicarbazide-sensitive amine oxidase (SSAO), with dl-alpha-methyltryptamine being the most potent and d-alpha-methylbenzylamine, the least. The three compounds, dl-alpha-methyltryptamine and the two isomers of alpha-methylbenzylamine also inhibited rat brain monoamine oxidase (MAO)-A and -B with a greater selectivity towards MAO-A. Preincubation of rat lung and brain homogenates with either of these compounds revealed that the inhibition of MAO and SSAO is reversible. The modes of inhibition of MAO-A and -B were competitive with the substrates tested. However, inhibition of SSAO by dl-alpha-methyltryptamine was found to be a mixed type (with a Ki value of 47 microM) and those by the racemic form and two isomers of alpha-methylbenzylamine were non-competitive (with Ki values of 90 microM for the racemic compound, 1070 microM for the d-isomer and 72 microM for the l-isomer). The present results indicate that SSAO can recognize optical isomers and that some alpha-methylated monoamines tested in the present study inhibit SSAO with properties different from those as MAO inhibitors.

Animals↗
PubMed2000

Conversion of Escherichia coli pyruvate oxidase to an 'alpha-ketobutyrate oxidase'.

Escherichia coli pyruvate oxidase (PoxB), a lipid-activated homotetrameric enzyme, is active on both pyruvate and 2-oxobutanoate ('alpha-ketobutyrate'), although pyruvate is the favoured substrate. By localized random mutagenesis of residues chosen on the basis of a modelled active site, we obtained several PoxB enzymes that had a markedly decreased activity with the natural substrate, pyruvate, but retained full activity with 2-oxobutanoate. In each of these mutant proteins Val-380 had been replaced with a smaller residue, namely alanine, glycine or serine. One of these, PoxB V380A/L253F, was shown to lack detectable pyruvate oxidase activity in vivo; this protein was purified, studied and found to have a 6-fold increase in K(m) for pyruvate and a 10-fold lower V(max) with this substrate. In contrast, the mutant had essentially normal kinetic constants with 2-oxobutanoate. The altered substrate specificity was reflected in a decreased rate of pyruvate binding to the latent conformer of the mutant protein owing to the V380A mutation. The L253F mutation alone had no effect on PoxB activity, although it increased the activity of proteins carrying substitutions at residue 380, as it did that of the wild-type protein. The properties of the V380A/L253F protein provide new insights into the mode of substrate binding and the unusual activation properties of this enzyme.

Amino Acid Substitution↗
PubMed1977

Spectrophotometric studies on NAD(P)H oxidase of leukocytes. 1. The relationship between granule-NAD(P)H oxidase and myeloperoxidase.

The NAD(P)H oxidase located in granules from resting leukocytes seems to be identical with myeloperoxidase on the basis of the following results. Spectral changes representing the difference between granules with and without NAD(P)H under various conditions represented the formation of compound III of myeloperoxidase, corresponding to the oxidation of NAD(P)H. The KCN difference spectrum of granules from both resting and phagocytizing leukocytes was in agreement with the KCN difference spectrum of myeloperoxidase. The affinity of KCN for myeloperoxidase was the same in both resting and phagocytizing leukocytes. The KCN-sensitive portion of NAD(P)H oxidase of granules from phagocytizing leukocytes seems to be identical with isolated myeloperoxidase and the myeloperoxidase of resting leukocytes. The KCN-insensitive oxidation of NAD(P)H by granules from phagocytizing leukocytes has not been found to be identical with myeloperoxidase.

Animals↗
PubMed1990

Properties of the NADPH dehydrogenase component of the oxidase complex from rabbit peritoneal neutrophils: reconstitution of an oxidase activity with the dehydrogenase component and a membrane extract.

A flavin-linked NADPH cytochrome c oxido-reductase of molecular mass 77-kDa was extracted from membranes of rabbit peritoneal neutrophils and purified in the presence of Triton X-100. The redox properties of this enzyme were examined. By some criteria including its high sensitivity to mersalyl, and its relatively high specificity for NADPH compared to NADH, the rabbit neutrophil NADPH cytochrome c reductase resembled NADPH-cytochrome P-450 reductase. Limited proteolysis generated water soluble fragments, with molecular masses of 67-kDa and 57-kDa, which were still endowed with a substantial reductase activity. When added to a lysate of neutrophil membranes in octylglucoside, in the presence of an oxidase activation medium consisting of rabbit neutrophil cytosol, GTP-gamma-S, arachidonic acid and Mg2+, the purified reductase enhanced the production of O2-., suggesting that it forms part of the O2-. generating oxidase.

Animals↗
PubMed1983

Rifamycin B oxidase from Monocillium spp., a new type of diphenol oxidase.

It was found that enzyme from a microbial strain, Monocillium spp. ATCC 20621, catalyzed the oxidative reaction of rifamycin B to form rifamycin O. The identification of the reaction products suggested that the reaction proceeded by the oxidative cyclization of rifamycin B to give rifamycin O, which spontaneously hydrolyzed to rifamycin S in neutral aqueous milieu. The characteristic of the enzyme was different as compared with that of other polyphenol oxidases such as laccase. It is proposed that this new type of enzyme be classified into a subgroup EC 1.10.3.6 with a trivial name rifamycin B oxidase.

Chromatography↗
PubMed1987

Purification of all thirteen polypeptides of bovine heart cytochrome c oxidase from one aliquot of enzyme. Characterization of bovine fetal heart cytochrome c oxidase.

A protocol has been worked out for separating all thirteen different polypeptides in the beef heart cytochrome c oxidase complex from a single aliquot of enzyme. This involves an initial separation of polypeptides by gel filtration on a Biogel P-60 column in SDS, a step which purifies subunits CIV and CVIII and gives mixtures of CV + CVI, ASA, AED and STA, as well as CVII, CIX and IHQ. These mixtures are then resolved by reverse-phase high-performance liquid chromatography. The separation procedures have been applied to fetal heart cytochrome c oxidase of gestation between 100 and 200 days. No differences were found in the N-terminal sequences of any of the cytoplasmically made subunits or in the entire sequence of CIX between late fetal and adult forms of the enzyme.

Animals↗
PubMed1992

Oxidation of methylamine by a Paracoccus denitrificans mutant impaired in the synthesis of the bc1 complex and the aa3-type oxidase. Evidence for the existence of an alternative cytochrome c oxidase in this bacterium.

A Paracoccus denitrificans fbcC-ctaDII double mutant strain impaired in the synthesis of both the bc1 complex and the aa3-type oxidase has been constructed. This mutant strain, which is still able to grow on methylamine as sole carbon and energy source, exhibits unimpaired oxygen consumption with succinate, methylamine and endogenous substrates as electron donors. From kinetic studies of the oxidation and reduction rates of cytochromes c, it can be concluded that P. denitrificans contains a second cytochrome c oxidase, different from the aa3-type.

Electron Transport Complex III↗
PubMed2004

Direct evidence for cyanide-insensitive quinol oxidase (alternative oxidase) in apicomplexan parasite Cryptosporidium parvum: phylogenetic and therapeutic implications.

Cryptosporidium parvum is a parasitic protozoan that causes the diarrheal disease cryptosporidiosis, for which no satisfactory chemotherapy is currently available. Although the presence of mitochondria in this parasite has been suggested, its respiratory system is poorly understood due to difficulties in performing biochemical analyses. In order to better understand the respiratory chain of C. parvum, we surveyed its genomic DNA database in GenBank and identified a partial sequence encoding cyanide-insensitive alternative oxidase (AOX). Based on this sequence, we cloned C. parvum AOX (CpAOX) cDNA from the phylum apicomplexa for the first time. The deduced amino acid sequence (335 a.a.) of CpAOX contains diiron coordination motifs (-E-, -EXXH-) that are conserved among AOXs. Phylogenetic analysis suggested that CpAOX is a mitochondrial-type AOX, possibly derived from mitochondrial endosymbiont gene transfer. The recombinant enzyme expressed in Escherichia coli showed quinol oxidase activity. This activity was insensitive to cyanide and highly sensitive to ascofuranone, a specific inhibitor of trypanosome AOX.

Amino Acid Sequence↗
PubMed2000

Heme-copper oxidase family structure of Magnetospirillum magnetotacticum 'cytochrome a1'-like hemoprotein without cytochrome c oxidase activity.

The genes encoding 'cytochrome a1'-like hemoprotein of Magnetospirillum magnetotacticum were identified and sequenced. Three ORFs, mcalI, mcaI and hosA, were included in the sequenced region. The six histidine residues which were predicted to associate with the prosthetic cofactors of heme-copper oxidase superfamily were conserved in the hemoprotein. However, none of the amino acid residues which were proposed to participate in the oxygen-reducing and the coupled proton pumping reactions in cytochrome c oxidase were at all conserved in the hemoprotein.

Amino Acid Sequence↗
PubMed2004

Cytochrome c oxidase subunit IV as a marker of protein kinase Cepsilon function in neonatal cardiac myocytes: implications for cytochrome c oxidase activity.

We have previously demonstrated that low concentrations of phorbol esters stimulate the selective translocation of protein kinase C (PKC) alpha and epsilon from the cell soluble to the particulate fraction in NCMs (neonatal rat cardiac myocytes). We therefore determined if the in vitro phosphorylation of substrates in these fractions could be used as assays of PKCalpha or epsilon activation. Intact cell phorbol ester treatment caused a decline in the in vitro (32)P-incorporation into several proteins in the cell-soluble fraction. These declines occurred in the presence or absence of in vitro Ca(2+) and probably reflected the exit of PKC isoenzymes from the soluble fraction. In contrast, an approx. 18 kDa protein incorporated (32)P in particulate fractions isolated from 4beta-PMA-treated cells in a Ca(2+)-independent manner. Proteomic and immunoprecipitation analyses indicated that the protein is subunit IV of the cytochrome c oxidase complex (COIV). In vitro phosphorylation of COIV was attenuated by PKC pseudosubstrate peptides. Introduction of an PKCepsilon-selective translocation inhibitor [Johnson, Gray, Chen and Mochly-Rosen (1996) J. Biol. Chem. 271, 24962-24966] into NCMs before 4beta-PMA treatments also attenuated the in vitro phosphorylation of COIV. In mitochondrial extracts from 4beta-PMA-treated NCMs, the PKCepsilon isoenzyme coimmunoprecipitated with COIV, and cytochrome c oxidase activity was enhanced 2-fold. The in vitro phosphorylation of COIV reflects a novel approach for monitoring PKCepsilon function in NCMs. Furthermore, PKCepsilon probably interacts with COIV in NCM mitochondria to enhance electron-transport chain complex IV activity.

Animals↗
PubMed2001

Purification of the aldehyde oxidase homolog 1 (AOH1) protein and cloning of the AOH1 and aldehyde oxidase homolog 2 (AOH2) genes. Identification of a novel molybdo-flavoprotein gene cluster on mouse chromosome 1.

We report the cloning of the AOH1 and AOH2 genes, which encode two novel mammalian molybdo-flavoproteins. We have purified the AOH1 protein to homogeneity in its catalytically active form from mouse liver. Twenty tryptic peptides, identified or directly sequenced by mass spectrometry, confirm the primary structure of the polypeptide deduced from the AOH1 gene. The enzyme contains one molecule of FAD, one atom of molybdenum, and four atoms of iron per subunit and shows spectroscopic features similar to those of the prototypic molybdo-flavoprotein xanthine oxidoreductase. The AOH1 and AOH2 genes are 98 and 60 kilobases long, respectively, and consist of 35 coding exons. The AOH1 gene has the potential to transcribe an extra leader non-coding exon, which is located downstream of exon 26, and is transcribed in the opposite orientation relative to all the other exons. AOH1 and AOH2 map to chromosome 1 in close proximity to each other and to the aldehyde oxidase gene, forming a molybdo-flavoenzyme gene cluster. Conservation in the position of exon/intron junctions among the mouse AOH1, AOH2, aldehyde oxidase, and xanthine oxidoreductase loci indicates that these genes are derived from the duplication of an ancestral precursor.

Aldehyde Oxidoreductases↗
PubMed2002

Purification of a cytochrome bc-aa3 supercomplex with quinol oxidase activity from Corynebacterium glutamicum. Identification of a fourth subunity of cytochrome aa3 oxidase and mutational analysis of diheme cytochrome c1.

The aerobic respiratory chain of the Gram-positive Corynebacterium glutamicum involves a bc(1) complex with a diheme cytochrome c(1) and a cytochrome aa(3) oxidase but no additional c-type cytochromes. Here we show that the two enzymes form a supercomplex, because affinity chromatography of either strep-tagged cytochrome b (QcrB) or strep-tagged subunit I (CtaD) of cytochrome aa(3) always resulted in the copurification of the subunits of the bc(1) complex (QcrA, QcrB, QcrC) and the aa(3) complex (CtaD, CtaC, CtaE). The isolated bc(1)-aa(3) supercomplexes had quinol oxidase activity, indicating functional electron transfer between cytochrome c(1) and the Cu(A) center of cytochrome aa(3). Besides the known bc(1) and aa(3) subunits, few additional proteins were copurified, one of which (CtaF) was identified as a fourth subunit of cytochrome aa(3). If either of the two CXXCH motifs for covalent heme attachment in cytochrome c(1) was changed to SXXSH, the resulting mutants showed severe growth defects, had no detectable c-type cytochrome, and their cytochrome b level was strongly reduced. This indicates that the attachment of both heme groups to apo-cytochrome c(1) is not only required for the activity but also for the assembly and/or stability of the bc(1) complex.

Amino Acid Sequence↗
PubMed2003

Regulation and biochemistry of mouse molybdo-flavoenzymes. The DBA/2 mouse is selectively deficient in the expression of aldehyde oxidase homologues 1 and 2 and represents a unique source for the purification and characterization of aldehyde oxidase.

Mouse molybdo-flavoenzymes consist of xanthine oxidoreductase, aldehyde oxidase (AOX1), and two recently identified proteins, AOH1 and AOH2 (aldehyde oxidase homologues 1 and 2). Here we demonstrate that CD-1, C57BL/6, 129/Sv, and other mouse strains synthesize high levels of AOH1 in the liver and AOH2 in the skin. By contrast, the DBA/2 and CBA strains are unique, having a selective deficit in the expression of the AOH1 and AOH2 genes. DBA/2 animals synthesize trace amounts of a catalytically active AOH1 protein. However, relative to CD-1 animals, an over 2 log reduction in the steady-state levels of liver AOH1 mRNA, protein, and enzymatic activity is observed in basal conditions and following administration of testosterone. The DBA/2 mouse represents a unique opportunity to purify AOX1 and compare its enzymatic characteristics to those of the AOH1 protein. The spectroscopy and biochemistry of AOX1 are very similar to those of AOH1 except for a differential sensitivity to the non-competitive inhibitory effect of norharmane. AOX1 and AOH1 oxidize an overlapping set of aldehydes and heterocycles. For most compounds, the substrate efficiency (V(max)/K(m)) of AOX1 is superior to that of AOH1. Alkylic alcohols and acetaldehyde, the toxic metabolite of ethanol, are poor substrates of both enzymes. Consistent with this, the levels of acetaldehyde in the livers of ethanol administered CD-1 and DBA/2 mice are similar, indicating that neither enzyme is involved in the in vivo biotransformation of acetaldehyde.

Aldehyde Oxidoreductases↗
PubMedDate not supplied

Auxin-activated NADH oxidase activity of soybean plasma membranes is distinct from the constitutive plasma membrane NADH oxidase and exhibits prion-like properties.

The hormone-stimulated and growth-related cell surface hydroquinone (NADH) oxidase activity of etiolated hypocotyls of soybeans oscillates with a period of about 24 min or 60 times per 24-h day. Plasma membranes of soybean hypocotyls contain two such NADH oxidase activities that have been resolved by purification on concanavalin A columns. One in the apparent molecular weight range of 14-17 kDa is stimulated by the auxin herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The other is larger and unaffected by 2,4-D. The 2,4-D-stimulated activity absolutely requires 2,4-D for activity and exhibits a period length of about 24 min. Also exhibiting 24-min oscillations is the rate of cell enlargement induced by the addition of 2,4-D or the natural auxin indole-3-acetic acid (IAA). Immediately following 2,4-D or IAA addition, a very complex pattern of oscillations is frequently observed. However, after several hours a dominant 24-min period emerges at the expense of the constitutive activity. A recruitment process analogous to that exhibited by prions is postulated to explain this behavior.

2,4-Dichlorophenoxyacetic Acid↗