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 433 records · Page 24Linked to original sources
PubMed1978

Oxidation of 3beta-hydroxyandrostenes by the 3beta-hydroxy-steroid oxidase (cholesterol oxidase) from Brevibacterium sterolicum prior to their analysis by gas-liquid chromatography-mass spectrometry.

The 3beta-hydroxysteroid oxidase from Brevibacterium sterolicum has been applied to the oxidation of a number of 3beta-hydroxyandrostenes, including polar steroids containing up to three other hydroxylic groups. The substrates, products, and derivatives thereof have been examined by gas-liquid chromatography. Retention index increments for these conversions, and for parallel transformations of other steroids, show considerable regularities, and together with mass spectrometric data afford characteristic structural information.

3-Hydroxysteroid Dehydrogenases↗
PubMed1995

Hydrogen peroxide (H2O2) production by monoamine oxidase in rat tissues using endogenous catecholamines as substrates. A comparison of catalytic monoamine oxidase histochemistry and recently published catechol-O-methyltransferase immunohistochemistry.

Histochemical studies on hydrogen peroxide (H2O2) production by monoamine oxidase (MAOX) using xenobiotic (foreign) catecholamines such as tryptamine or tyramine as substrates may not reveal the true H2O2-production capacity of this enzyme and the potential co-localization and cooperation of MAOX with catechol-O-methyltransferase (COMT), the other catecholamine-degrading enzyme. Therefore, in the present study the catecholamine hormones adrenaline (epinephrine) and noradrenaline (norepinephrine) and the catecholamine neurotransmitter noradrenaline as well as the COMT metabolites metanephrine and normetanephrine, which are likely to be the more important MAOX substrates, were used for MAOX visualization in many rat tissues with a cerium-diaminobenzidine-H2O2-Co method. Adrenaline and noradrenaline were autooxidized by Ce3+ and could not be employed; with metanephrine or normetanephrine as substrates MAOX produced considerable amounts of H2O2 in many cells and tissues. Comparisons with immunohistochemical COMT-data for rats from the literature show that MAOX and COMT are co-localized or not. Therefore, different from our current knowledge in rats COMT and MAOX either co-operate in catecholamine degradation or they degrade the respective catecholamines alone.

Animals↗
PubMed2000

Molecular cloning and expression patterns of three putative functional aldehyde oxidase genes and isolation of two aldehyde oxidase pseudogenes in tomato.

The final steps in the biosynthesis of the plant hormones abscisic acid (ABA) and indole-3-acetic acid (IAA) have been shown to be catalyzed by aldehyde oxidases (AO). We have cloned three putative functional AO genes (TAO1, TAO2 and TAO3) and two putative AO pseudogenes (TAO4 and TAO5) in tomato. The TAO1 cDNA described here includes the correct amino terminus of the encoded TAO1 protein and is different at the 5'-end from the TAO1 sequence in GenBank (accession number U82558). Northern analysis shows that TAO1 is expressed mainly in vegetative tissues and TAO2 is expressed in both vegetative and reproductive tissues. TAO3 expression was not detectable by Northern hybridization. These results suggest that each AO may play different roles in the regulation of tomato growth and development.

Aldehyde Oxidase↗
PubMed2000

Styrene inhibits monoamine oxidase A, but not monoamine oxidase B in monkey brain mitochondria.

The effects of styrene on mitochondrial monoamine oxidase (MAO) activity in rat and monkey brains were compared in vitro. After preincubation at 25 degrees C for 20 min with 1 mM styrene monomer MAO-A activity in monkey brain was inhibited potently using 5-HT (for MAO-A substrate), but MAO-B activity in monkey brain and platelets were slightly inhibited using beta-PEA (for MAO-B substrate). Styrene monomer also competitively inhibited MAO-A activity in a dose-dependent manner. MAO-A in monkey brain was inhibited by styrene in ascending order of potency: styrene trimer>styrene dimer>styrene monomer. In contrast styrene monomer slightly inhibited both MAO-A and MAO-B activities in rat brain mitochondria. In the present study styrene monomer potently inhibits MAO-A activity, but not MAO-B activity, in monkey brain mitochondria in vitro. These results indicate the inhibiting action of styrene differs depending on animal species and MAO isoforms.

Animals↗
PubMed1988

The glycoprotein nature of pig kidney diamine oxidase. Role of disulphide groups and arginine residues in the concanavalin A-diamine oxidase interaction.

Pig kidney diamine oxidase (DAO) was found to contain 5% (w/w) natural hexose, 3.25% glucosamine, 2.61% N-acetylglucosamine and 0.25% N-acetylneuraminic acid. The enzyme exhibited strong affinity towards concanavalin A (Con A) with a stoichiometry of 1:4.6. The kinetics of interaction approached an apparent first-order rate, with a rate constant (Kapp.) value of 1.5 x 10(-2) min-1. The enzyme reduced with dithiothreitol followed by alkylation with iodoacetamide showed an increase in the stoichiometry of the Con A-DAO interaction. Similarly arginine modification by phenylglyoxal caused decreased affinity, with an altered Kapp. value of 9.09 x 10(-3) min-1. The results suggest that, besides the carbohydrate content, the protein moiety of the enzyme also plays a significant role in the Con A-DAO interaction.

Amine Oxidase (Copper-Containing)↗
PubMed2006

Forebrain-specific expression of monoamine oxidase A reduces neurotransmitter levels, restores the brain structure, and rescues aggressive behavior in monoamine oxidase A-deficient mice.

Previous studies have established that abrogation of monoamine oxidase (MAO) A expression leads to a neurochemical, morphological, and behavioral specific phenotype with increased levels of serotonin (5-HT), norepinephrine, and dopamine, loss of barrel field structure in mouse somatosensory cortex, and an association with increased aggression in adults. Forebrain-specific MAO A transgenic mice were generated from MAO A knock-out (KO) mice by using the promoter of calcium-dependent kinase IIalpha (CaMKIIalpha). The presence of human MAO A transgene and its expression were verified by PCR of genomic DNA and reverse transcription-PCR of mRNA and Western blot, respectively. Significant MAO A catalytic activity, autoradiographic labeling of 5-HT, and immunocytochemistry of MAO A were found in the frontal cortex, striatum, and hippocampus but not in the cerebellum of the forebrain transgenic mice. Also, compared with MAO A KO mice, lower levels of 5-HT, norepinephrine, and DA and higher levels of MAO A metabolite 5-hydroxyindoleacetic acid were found in the forebrain regions but not in the cerebellum of the transgenic mice. These results suggest that MAO A is specifically expressed in the forebrain regions of transgenic mice. This forebrain-specific differential expression resulted in abrogation of the aggressive phenotype. Furthermore, the disorganization of the somatosensory cortex barrel field structure associated with MAO A KO mice was restored and became morphologically similar to wild type. Thus, the lack of MAO A in the forebrain of MAO A KO mice may underlie their phenotypes.

Animals↗
PubMed1976

Digestion and absorption of bovine milk xanthine oxidase and its role as an aldehyde oxidase.

The effects of acidic and intestinal proteolytic environments on bovine milk xanthine oxidase (XO) activity were determined in order to evaluate the extent to which this enzyme was absorbed in biologically active form. The inhibition of XO by folic acid and the relative affinities of XO for the oxidation of palmitaldehyde, stearaldehyde, and xanthine were compared. The effects of acid and gastric juice on XO activity were measured by incubating purified enzyme, and non-purified enzyme (milk), in buffers ranging in pH from 2 to 9. Fresh gastric juice was also incubated with milk. Increasing amounts of the enzyme were inactivated as the pH of the incubation mixture was reduced below pH 6.5. Below pH 3.5, the enzyme was completely inactivated. Gastric juice, pH juice incubated with milk. Milk XO activity was reduced 36% when mild was incubated with an equal volume of gastric juice. Homogenized milk had 59% less XO activity compared with raw molk. Fresh raw milk XO, homogenized milk XO, and purified XO were equally susceptible to inactivation by acid or gastric juice. After incubation of milk with gastric juice, or gastric juice followed by pancreatin, XO activity was associated with a macromolecule of 300,000 daltons molecular weight and subunits containg activity were not found. It was estimated that 0.00008% of the XO in the intestine was absorbed. Both folic acid and allopurinol inhibited XO activity in vitro. Allopurinol was 3.5 times more potent an inhibitor than folic acid. A large excess of dietary folic acid did not reduce rat liver or intestinal XO activity in vivo. XO had a much greater affinity for xanthine than for palmitaldehyde or stearaldehyde substrates. It was estimated that of 100 mg of XO in fresh raw milk, 41 mg remained after homogenization, 27 mg entered the intestine and only 20 ng were absorbed as intact enzyme.

Absorption↗
PubMed1985

Protoporphyrin accumulation by mitogen stimulated lymphocytes and protoporphyrinogen oxidase activity in patients with porphyria variegata and erythropoietic protoporphyria: evidence for deficiency of protoporphyrinogen oxidase and ferrochelatase in both diseases.

In erythropoietic protoporphyria (EPP) and porphyria variegata (PV) excess protoporphyrin is excreted in the stool, suggesting one or more enzyme defects in the terminal steps of the haem biosynthetic pathway. We measured protoporphyrinogen oxidase (PPO), which catalyses the oxidation of protoporphyrinogen to protoporphyrin, in both EPP and PV patients and in the offspring of PV patients. In the same subjects we measured protoporphyrin formation by mitogen stimulated lymphocytes, with delta aminolaevulinic acid (ALA) as substrate and with the addition of chelators or iron, an indirect measure of ferrochelatase activity. PPO activity was reduced by 41% (P less than 0.001) in PV patients and in 50% of their offspring, and by 36% (P less than 0.001) in EPP patients. Protoporphyrin accumulation in stimulated lymphocytes was increased by 1.3-fold (P less than 0.001) in EPP and 1.5-fold (P less than 0.001) in PV patients compared to normal subjects. There was a significant difference in protoporphyrin accumulation between iron deficient and iron replete cells from PV patients as compared to normals but not as marked as for EPP cells treated similarly. Stimulated lymphocytes from prepubertal PV offspring with reduced PPO activity accumulated normal amounts of protoporphyrin. We have interpreted our findings as follows: PPO is significantly reduced in both diseases. Ferrochelatase becomes defective in PV patients after puberty. This could explain why PV is clinically and biochemically manifest only after puberty. As it has been repeatedly shown that ferrochelatase is markedly reduced in EPP, it would appear that both enzymes are deficient in these two porphyrias.

Adult↗
PubMed1976

Structure of flavin adducts with acetylenic substrates. Chemistry of monoamine oxidase and lactate oxidase inhibition.

The photoreaction of flavoquinones (lumiflavin, riboflavin, FMN etc. and their 3-alkylated derivatives) with propargylamine-type acetylenic substrates, R4 -Calpha identical to Cbeta -CgammaHR3 -NR2R1, yields a mixture of two adducts,which result from covalent Calpha fixation of the Cgamma-deprotonated substrate to either position C(4a) or N(5) in the flavin nucleus. The N(5) adduct is a dihydroflavin-5-trimethine-cyanine with very intense (xi greater than 20000 M-1 cm-1) absorption maxima in the region 380-450 nm depending on the R1,R2. This absorption allows recognition of minute amounts of this species of flavocyanine even in complex mixtures. Flavocyanines can be reconverted to starting flavin by base. It spectral properties are identical with those obtained for the pargyline-flavin inhibitor complex from bovine kidney or pig liver monoamine oxidase.

Acetylene↗
PubMed2005

Novel multifunctional neuroprotective iron chelator-monoamine oxidase inhibitor drugs for neurodegenerative diseases: in vitro studies on antioxidant activity, prevention of lipid peroxide formation and monoamine oxidase inhibition.

Iron-dependent oxidative stress, elevated levels of iron and of monoamine oxidase (MAO)-B activity, and depletion of antioxidants in the brain may be major pathogenic factors in Parkinson's disease, Alzheimer's disease and related neurodegenerative diseases. Accordingly, iron chelators, antioxidants and MAO-B inhibitors have shown efficacy in a variety of cellular and animal models of CNS injury. In searching for novel antioxidant iron chelators with potential MAO-B inhibitory activity, a series of new iron chelators has been designed, synthesized and investigated. In this study, the novel chelators were further examined for their activity as antioxidants, MAO-B inhibitors and neuroprotective agents in vitro. Three of the selected chelators (M30, HLA20 and M32) were the most effective in inhibiting iron-dependent lipid peroxidation in rat brain homogenates with IC50 values (12-16 microM), which is comparable with that of desferal, a prototype iron chelator that is not has orally active. Their antioxidant activities were further confirmed using electron paramagnetic resonance spectroscopy. In PC12 cell culture, the three novel chelators at 0.1 microM were able to attenuate cell death induced by serum deprivation and by 6-hydroxydopamine. M30 possessing propargyl, the MAO inhibitory moiety of the anti-Parkinson drug rasagiline, displayed greater neuroprotective potency than that of rasagiline. In addition, in vitro, M30 was a highly potent non-selective MAO-A and MAO-B inhibitor (IC50 < 0.1 microM). However, HLA20 was more selective for MAO-B but had poor MAO inhibition, with an IC50 value of 64.2 microM. The data suggest that M30 and HLA20 might serve as leads in developing drugs with multifunctional activities for the treatment of various neurodegenerative disorders.

Animals↗
PubMed2005

Novel multifunctional neuroprotective iron chelator-monoamine oxidase inhibitor drugs for neurodegenerative diseases. In vivo selective brain monoamine oxidase inhibition and prevention of MPTP-induced striatal dopamine depletion.

Several multifunctional iron chelators have been synthesized from hydroxyquinoline pharmacophore of the iron chelator, VK-28, possessing the monoamine oxidase (MAO) and neuroprotective N-propargylamine moiety. They have iron chelating potency similar to desferal. M30 is a potent irreversible rat brain mitochondrial MAO-A and -B inhibitor in vitro (IC50, MAO-A, 0.037 +/- 0.02; MAO-B, 0.057 +/- 0.01). Acute (1-5 mg/kg) and chronic [5-10 mg/kg intraperitoneally (i.p.) or orally (p.o.) once daily for 14 days]in vivo studies have shown M30 to be a potent brain selective (striatum, hippocampus and cerebellum) MAO-A and -B inhibitor. It has little effects on the enzyme activities of the liver and small intestine. Its N-desmethylated derivative, M30A is significantly less active. Acute and chronic treatment with M30 results in increased levels of dopamine (DA), serotonin(5-HT), noradrenaline (NA) and decreases in DOPAC (dihydroxyphenylacetic acid), HVA (homovanillic acid) and 5-HIAA (5-hydroxyindole acetic acid) as determined in striatum and hypothalamus. In the mouse MPTP (N-methy-4-phenyl-1,2,3,6-tetrahydropyridine) model of Parkinson's disease (PD) it attenuates the DA depleting action of the neurotoxin and increases striatal levels of DA, 5-HT and NA, while decreasing their metabolites. As DA is equally well metabolized by MAO-A and -B, it is expected that M30 would have a greater DA neurotransmission potentiation in PD than selective MAO-B inhibitors, for which it is being developed, as MAO-B inhibitors do not alter brain dopamine.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1984

Inhibition of semicarbazide-sensitive amine oxidase by monoamine oxidase B inhibitors from the oxazolidinone series.

The purpose of the present work was to study the semicarbazide-sensitive amine oxidase (SSAO) inhibitory properties of MD 240931 and MD 240928 (the two enantiomers of MD 780236) as well as those of the corresponding primary amines, MD220662 and MD220661, in rat heart and aorta. MD240928 and MD240931 are rather weak SSAO inhibitors, MD 240931 being more potent than MD 240928. Of the four compounds studied, the most potent inhibitor of SSAO is MD 220662, its IC50 value ranging from 2.10(-6) to 6.10(-6)M. The SSAO inhibitory potency of this compound does not change significantly with the time of preincubation in both the absence and presence of clorgyline (10(-4)M). MD 220661 is also an inhibitor of SSAO; however, its SSAO inhibitory potency, which without preincubation is comparable to that of MD 220662, does decrease with the time of preincubation to the same extent in both the absence and presence of clorgyline (10(-4)M). These results suggest that MD 220661 is not only an inhibitor of SSAO, but is also a substrate of the enzyme.

Animals↗
PubMed2002

Resistance to protoporphyrinogen oxidase-inhibiting compound S23142 from overproduction of mitochondrial protoporphyrinogen oxidase by gene amplification in photomixotrophic tobacco cells.

Tobacco YZI-IS cells exhibit a 150-fold greater resistance to the protoporphyrinogen oxidase (Protox)-inhibiting compound, S23142, from wild-type tobacco cells. To investigate the mechanism for this S23142 resistance, the protein level, enzymatic activity, and sensitivity to S23142 in two Protox isoenzymes (plastidal and mitochondrial forms) were examined. The level of mitochondrial Protox protein was greater, and its activity 5-times higher, in YZI-IS cells than in wild-type cells. Furthermore, the apparent IC50 value of S23142 was about 20 nM, which is 20-fold higher than that observed in wild-type cells. In contrast, no differences were found in the plastidal Protox protein level, activity or its inhibition by S23142 between YZI-1S and wild-type cells. A southern blot analysis revealed that the mitochondrial Protox gene had been significantly amplified in the YZI-1S cells. These results suggest that the S23142 resistance of YZI-1S cells was due to the overproduction of mitochondrial Protox by gene amplification.

Dose-Response Relationship, Drug↗
PubMed2002

[Various mammalian tissues contain cell membrane-bound amine oxidase termed semicarbazide-sensitive amine oxidase (SSAO, EC 1.4.3.6)].

Recently it has been demonstrated a role of fat-cell SSAO on glucose transport and GLUT4 translocation to the cell surface. Many compounds have been identified as relatively selective SSAO inhibitors, but those currently available also inhibit monoamine oxidase (MAO, EC 1.4.3.4). In this study, inhibitory properties of a haloamine, 2-bromoethylamine (2-BEA), to guinea pig and rat lung-bound SSAO have been studied. 2-BEA could not inhibit both forms of MAO, but it competitively inhibited rat lung SSAO activity with a Ki value of 2.5 microM without preincubation and after preincubation, the mode of inhibition changed to be non-competitive. Dialysis and dilution experiments with 2-BEA-pretreated preparations resulted in no recovery of SSAO activity. A decreased rate of SSAO inhibition under N2 atmosphere to that obtained under O2 was produced after 2-BEA treatment, suggesting that oxidised intermediate was necessary for its inhibition. The plot of 1/k' vs 1/2-BEA intersected on the y-axis indicate that the inhibition by 2-BEA is not affinity-labeling agent, but a suicide inhibitor of SSAO.

Amine Oxidase (Copper-Containing)↗
PubMed1985

Immunological uniqueness of human monoamine oxidases A and B: new evidence from studies with monoclonal antibodies to human monoamine oxidase A.

Monoamine oxidase (EC 1.4.3.4; MAO) is the primary enzyme responsible for the intraneuronal degradation of biogenic amines in the central nervous system. An understanding of the physiological significance of the functional and regulatory differences between the two forms of the enzyme, MAOs A and B, would be facilitated by the availability of antibodies specific for the two forms of the enzyme. We previously isolated and characterized a monoclonal antibody (MAO B-1C2, previously designated MAO-1C2) which binds human MAO B but not A. We describe here four new monoclonal antibodies (designated MAO A-3C9, A-4F10, A-7B10, and A-7E10) which were elicited to highly purified MAO A from human placenta and which, in the presence of antimouse IgG and Staphylococcus aureus, immunoprecipitate greater than 90% of the catalytically active purified MAO A. MAO A-3C9 appears to have a lower affinity for purified MAO A than the other three antibodies and does not immunoprecipitate either MAO A or MAO B from human platelets or from Triton X-100 extracts of human placental and liver mitochondria. MAO A-4F10, A-7B10, and A-7E10 immunoprecipitate catalytically active MAO A from Triton X-100 extracts of human placental and liver mitochondria, but not catalytically active MAO B from either pletelets or from Triton X-100 extracts of human liver mitochondria. Collectively, these anti-MAO monoclonal antibodies reveal unique epitopes on human MAO A not shared by MAO B, and at least one epitope on MAO B not shared by MAO A. These immunochemical differences support the hypothesis that MAO A and MAO B are different proteins, presumably isozymes.

Antibodies, Monoclonal↗
PubMed1987

[Substances inhibiting amine oxidases. III. Synthesis and amine oxidase inhibition of imidazoquinoline derivatives].

The activity of copper and FAD dependent amine oxidases was tested with some derivatives of 3H-imidazo[4,5-h]quinoline and its isomers 3H-imidazo[4,5-f]quinoline, the chemistry of which is described in the literature (1), and Ki calculated. The methyl derivative of 3H-imidazo[4,5-f]quinoline was found to activate the copper bovine serum enzyme, but inhibits the FAD mitochondrial enzyme.

Animals↗
PubMed1986

The effect of chronic ozone exposure on lung benzo(a)pyrene oxidase, benzphetamine demethylase and monoamine oxidase.

Adult male Fischer 344 rats were exposed either to clean air or to a mixture of clean air and 0.5ppm ozone for up to one year. These populations were sampled after three and six months and when the exposure was completed. The activity of several oxidative enzymes in these rat lungs were compared. Although there was no significant increase in the ability of pulmonary microsomes to oxidize benzo[alpha]pyrene after three months of exposure to ozone, this activity and the oxidative demethylation of benzphetamine were increased after six months and a year of exposure. Aside from these enzymatic changes, electrophoretic analysis indicated that the microsomes from ozone exposed rats were enriched with a protein with an apparent molecular weight of 68,000. The activity of the two isoenzymic forms of monoamine oxidase, MAO A and MAO B, were also measured, and neither activity was affected by the ozone exposure.

Animals↗
PubMed1982

A monoclonal antibody elicited to human platelet monoamine oxidase. Isolation and specificity for human monoamine oxidase B but not A.

We have isolated a mouse monoclonal antibody to human platelet monoamine oxidase (MAO) B. The antibody (MAO-1C2) was isolated from a fusion of mouse myeloma P3/X63 Ag8 to spleen cells from a BALB/c mouse immunized with a partially purified platelet preparation in which an estimated 21-31% of the protein was [3H]pargyline-labeled MAO B. The antibody indirectly immunoprecipitates both [3H]pargyline-labeled, catalytically inactive human MAO B, and unlabeled, catalytically active human MAO B. Binding of the antibody to MAO B has no detectable effect on catalytic activity. MAO-1C2 is specific for human MAO B, and fails to immunoprecipitate MAO A indirectly from human placenta or liver. Its ability to immunoprecipitate human MAO B but not MAO A from extracts of human liver provides a convenient technique for separating the two forms of the enzyme for comparative studies. The antibody does not recognize mouse liver MAO B, suggesting that the determinant is not universally expressed on MAO B from all species.

Animals↗