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At least 343 records · Page 19Linked to original sources
PubMed1984

Monitoring treatment of pulmonary carcinomas by serial determination of monoamine oxidase and diamine oxidase in blood serum.

We investigated monoamine oxidase (MAO--E.C. 1.4.3.4.) and diamine oxidase (DAO--E. C. 1.4.3.6.) in the serum of patients with lung cancer, treated with chemo- and radiotherapy. These enzyme activities were determined with tyramine and putrescine as substrates. The MAO activities of serum and DAO serum increased notably in some cases of lung cancer. These results are discussed in light of the postulated role of this enzyme in cell division and in the tumor development process.

Adult↗
PubMed1984

[Monoamine oxidase and diamine oxidase activity of the tissues of rats in the convulsive phase of oxygen poisoning].

Monoamine oxidase type A activity with substrate serotonine and type B with substrate p-nitrophenylethylamine decreases is rats' brain, liver, heart and blood during oxygen convulsions. Substrate specificity of the enzyme type A alters in all tissues studied. Diamine oxidase activity decreases in brain, lungs and liver approximately in 2 times and increases in blood at 48%. Histamine content increases in all tissues in 3-4 times, in blood--in 12 times. The role of observed changes in the mechanism of oxygen intoxication is discussed.

Amine Oxidase (Copper-Containing)↗
PubMed1983

Effect of ovariectomy and estrogen treatment on uterine benzylamine oxidase and monoamine oxidase type A.

The activity of monoamine oxidase type A (MAO-A) of rat uteri is known to be modulated by sex steroids but no information is available with regard to benzylamine oxidase (BzAO). Thus, uterine MAO-A and BzAO activities were assayed in ovariectomized (3 weeks) and ovariectomized plus estrogen treated rats (17 beta-estradiol, 10 micrograms/kg/day, i.p. for three days). Compared with sham operated controls, MAO-A activity (total and specific) was decreased by ovariectomy and restored partially by estrogen treatment. In contrast, BzAO activity was not influenced selectively. Total BzAO activity followed changes in uterine weight such that the specific activity of BzAO, per mg tissue, was not statistically different between the three experimental groups. Although changes in the specific activity of BzAO were found on a protein and DNA basis, these changes reflect primarily alterations in protein and DNA contents and not BzAO activity. Since BzAO appears to be insensitive to direct modulation by sex steroids and may be located predominantly in uterine blood vessels, it is speculated that the enzyme may serve as a marker for hormonal influences on the vascularity and structure of the uterine vascular bed.

Animals↗
PubMed2004

Enhanced fructose oxidase activity in a galactose oxidase variant.

Galactose oxidase (GO; EC 1.1.3.9) catalyses the oxidation of a wide range of primary alcohols including mono-, oligo- and polysaccharides. High-resolution structures have been determined for GO, but no structural information is available for the enzyme with bound substrate or inhibitor. Previously, computer-aided docking experiments have been used to develop a plausible model for interactions between GO and the D-galactose substrate. Residues implicated in such interactions include Arg330, Gln406, Phe464, Phe194 and Trp290. In the present study we describe an improved expression system for recombinant GO in the methylotrophic yeast Pichia pastoris. We use this system to express variant proteins mutated at Arg330 and Phe464 to explore the substrate binding model. We also demonstrate that the Arg330 variants display greater fructose oxidase activity than does wild-type GO.

Crystallography, X-Ray↗
PubMed1988

Minute mutations of Drosophila melanogaster change aldehyde oxidase and pyridoxal oxidase distribution patterns in imaginal wing discs.

Aldehyde oxidase (AO) and pyridoxal oxidase (PO) distribution patterns were determined in the imaginal wing discs for a series of strains of Drosophila melanogaster heterozygous for different Minute mutations. The mutant severity ranged from very weak to strong. The results shown an inverse response of AO and PO to the expressivity of the Minute mutation: in weaker Minutes the extent of the AO positive area increases, whereas PO activity disappears. The results are discussed with reference to an impaired protein synthesis in Minutes.

Aldehyde Oxidase↗
PubMedDate not supplied

A novel colorimetric assay and activity staining for cytokinin oxidase based on the copper amine oxidase property of the enzyme.

A rapid and sensitive colorimetric assay for cytokinin oxidase (CKO) was developed based on the copper amine oxidase property of the enzyme from cucumber cotyledons. The assay involved oxidation of isopentenyl adenine by CKO in the presence of phenazine methosulphate as an electron acceptor, resulting in reduction of nitroblue tetrazolium to formazon. The formation of formazon was linear with time for at least 20 min and could be followed spectrophotometrically at A490. CKO could also be specifically stained on polyacrylamide gels using the same principle.

Amine Oxidase (Copper-Containing)↗
PubMed1993

Rapid and simultaneous determination of monoamine oxidase A and monoamine oxidase B activities in mouse brain homogenates by liquid chromatography with electrochemical detection.

Sensitive and rapid enzymatic assays have been developed and optimized to measure the separate and combined activities of monoamine oxidase A (MAO-A) and monoamine oxidase B (MAO-B) in mouse brain tissue homogenates using liquid chromatography with electrochemical detection (LCEC). The selectivity for the two isozymes is primarily afforded by use of selective substrates, 5-hydroxytryptamine (5-HT) for MAO-A and 3-methoxy-4-hydroxybenzylamine (MHBA) for MAO-B. The selectivity of the separate assays is further enhanced by the use of inhibitors, deprenyl to block MAO-B and clorgyline to block MAO-A. The dual assay procedure, which employs no inhibitors, shows remarkably enhanced selectivity for each of the isozymes through the use of the two substrates; the preferred substrate for one isozyme acts as an effective competitive inhibitor of the nontargeted substrate for that isozyme, leading to substantially decreased activity for the latter substrate. Using the dual assay, kinetic constants determined for MAO-A (mean +/- SD) were: Km,5-HT = 39 +/- 7 microM, Vmax,5-HT = 37.6 +/- 2.1 pmol/mg wet tissue/min, Km,MHBA = 341 +/- 75 microM, and Vmax,MHBA = 27.7 +/- 2.3 pmol/mg wet tissue/min; those for MAO-B were: Km,MHBA = 108 +/- 11 microM, Vmax,MHBA = 44.3 +/- 1.2 pmol/mg wet tissue/min, Km,5-HT = 1704 +/- 122 microM, and Vmax,5-HT = 12.0 +/- 0.3 pmol/mg wet tissue/min. The separate isozyme procedures, when used without selective inhibitors, reflect only 88.3% of the MAO-A activity using the 5-HT velocity and only 66.0% of the MAO-B activity using the MHBA velocity. On the other hand, when the dual assay is employed, 98% of the observed 5-HT velocity can be directly attributed to MAO-A, and 94% of the observed MHBA velocity can be directly attributed to MAO-B. The dual assay was employed to demonstrate the relative change in the activity of these two enzymes in whole mouse brain between 27 and 74 days of age. During this time, the MAO-B activity increased from approximately 40 to approximately 60% of the total MAO activity. Under typical conditions, results can be easily obtained from any of the three procedures outlined for 100 samples in less than 2 working days, including only 3.5 h for the LCEC portion.

Animals↗
PubMed1995

Identification of topaquinone, as illustrated for pig kidney diamine oxidase and Escherichia coli amine oxidase.

Pig kidney diamine oxidase was purified to homogeneity. The reaction product of the cofactor with p-nitrophenylhydrazine (pNPH) was liberated with pronase treatment and purified. 1H NMR, uv/vis, and electrospray tandem mass spectroscopy revealed it to be a dipeptide with the sequence topaquinone-pNPH and aspartate. No heterogeneity was observed, indicating that no intramolecular cyclization of the quinone moiety occurs in the time span of the isolation and of the measurements. Similar results were obtained with the more widely applicable reagent, phenylhydrazine, and using the aromatic amine oxidase from Escherichia coli. From the amount and ease with which the dipeptide could be isolated, the procedure used here is more convenient than the existing one for the identification of protein-integrated quinone cofactors.

Amine Oxidase (Copper-Containing)↗
PubMed1986

The effect of mixed-function oxidase and amine oxidase inhibitors on the activation of dialkylnitrosamines and 1,2-dimethylhydrazine to bacterial mutagens in mice.

The effect of the mixed-function oxidase inhibitor phenylimidazole (PI) and the amine oxidase inhibitors iproniazid (IPRO) and aminoacetonitrile (AAN) on the mutagenic activity of various carcinogens was determined in intrasanguineous host-mediated assays, using mice as hosts and E. coli 343/113 as an indicator of mutagenic activity. The carcinogenic compounds dimethyl-, diethyl-, methylethyl-, and diethanolnitrosamine (DMNA, DENA, MENA, and DELNA respectively) and 1,2-dimethylhydrazine (SDMH) were administered i.p. to mice pretreated or not with one of the inhibitors. After 4 h exposure to each of the carcinogens, E. coli cells recovered from the liver of non-pretreated mice showed considerable induction of VALr mutations; after pretreatment of the hosts with the three inhibitors, significant reduction of the amounts of induced mutants in vivo was observed. Particularly, PI proved a very efficient inhibitor of DENA, MENA, DELNA, and SDMH mutagenicity (93%-97% reduction), suggesting that these carcinogens are mainly activated by cytochrome P-450-dependent enzymes. However, since PI might also inhibit the NAD-mediated activation of DELNA by alcohol dehydrogenase (ADH), the present experiments do not rule out an additional role of ADH in the in vivo mutagenic activation of DELNA. AAN and IPRO were less and much less effective, respectively, in reducing the mutagenic activity of all compounds. Surprisingly, PI showed less inhibition of the mutagenic activity of DMNA (60% reduction), as compared to the other carcinogens; this indicates that metabolic routes other than the cytochrome P-450-dependent enzyme system may be important for the activation of DMNA.

1,2-Dimethylhydrazine↗
PubMed1976

Genetics of peroxisomal enzymes in the mouse: nonlinkage of D-amino acid oxidase locus (Dao) to catalase (Cs) and L-alpha-hydroxyacid oxidase (Hao-1) loci on chromosome 2.

An electrophoretic polymorphism of the peroxisomal enzyme D-amino acid oxidase was observed in NZC strain Mus musculus. F1 (NZC X BALB/c) mice showed a codominant allcle two-banded phenotype which is inconsistent with the dimeric subunit structure reported for this enzyme in other species. The enzyme locus (Dao) was shown to segregate independently of Hao-1, encoding the peroxisomal enzyme hydroxyacid oxidase (liver on A4 isozyme). Thus Dao is not linked to previously mapped peroxisomal enzyme loci, Hao-1 and Cs, closely localized on chromosome 2.

Animals↗
PubMed1976

Oxidation of S-e-carboxymethyl-selenocysteine by L-aminoacid oxidase and by D-aspartate oxidase.

Se-Carboxymethyl-DL-selnocysteine (CMSeC) has been prepared in a pure crystalline form from selenocysteine and monochloracetic acid. It has been shown that CMSeC is a substrate for the L-aminoacid oxidase form snake venom and for the D-aspartate oxidase from beef kidney. Oxygen consumption and ammonia production indicate that only the L or the D form of CMSeC ar acted upon respectively by one or the other of the above enzymes. No noticeable differences were shown in the oxidation rate of CMSeC and S-carboxymethylcysteine, an indication that the substitution of a selenium for a sulfur atom in the molecule does not greatly affect the substrate specificity of the two enzymes. Data have been obtained suggesting that the product of the oxidative deamination of CMSeC Is Se-carboxymethyl-selenopyruvic acid.

Amino Acid Oxidoreductases↗
PubMed1978

Combined deficiency of xanthine oxidase and sulphite oxidase: a defect of molybdenum metabolism or transport?

A child is described who presented in the neonatal period with feeding difficulties, severe neurological abnormalities, lens dislocation of the eyes and dysmorphic symptoms of the head. Routine laboratory investigations revealed a decreased serum urate and a positive sulphite reaction of the urine. Subsequent chromatographic examinations showed xanthinuria and increased excretion of S-sulphocysteine and taurine to be present. In addition, high thiosulphate and low sulphate excretions in the urine were observed. Xanthine oxidase deficiency was demonstrated in a jejunal biopsy specimen, whereas the excretion of sulphur containing substances was considered to be characteristic of sulphite oxidase deficiency. This new combination of defects may be the result of malfunctioning of both enzymes, possibly caused by alterations in the essential molybdenum containing active centre of the enzymes, which they share in common.

Abnormalities, Multiple↗
PubMed2004

Comparative immunocytochemical localization of lysyl oxidase (LOX) and the lysyl oxidase-like (LOXL) proteins: changes in the expression of LOXL during development and growth of mouse tissues.

Lysyl oxidase (LOX) and lysyl oxidase-like (LOXL) are extracellular enzymes that deaminate peptidyl lysyl residues involved in the cross-linking of fibrillar collagens and elastin. While LOX is required for the survival of newborn mice, the role of LOXL during development remains unclear. Studies have shown that the same cell types express LOX and LOXL in the same tissues, but no functional differences have been established. We have compared the immunohistochemical localization of LOX and LOXL in various tissues from normal, young adult mice. LOX and LOXL were co-localized in the skin, aorta, heart, lung, liver and cartilage, but were localized to different areas in the kidney, stomach, small intestine, colon, retina, ovary, testis and brain. LOXL expression was further examined in tissues from different developmental stages. In embryonic mice (10.5-14.5 dpc), LOXL immunostaining was abundant in the heart, liver, intestine, and neural tube. LOXL was present in most major organs in late fetal (16.5 dpc) and newborn mice, but generally diminished as animals aged. Immunoreactivity was significantly reduced in the heart, lung, kidney and liver of 2 year-old mice, but remained prevalent in the skin and tongue. LOX and LOXL were also found in the nuclei of cells in a number of tissues. These results indicate that LOXL has a role during mouse development and in the maintenance of adult tissues.

Aging↗
PubMed1991

2-propyl-1-aminopentane, its deamination by monoamine oxidase and semicarbazide-sensitive amine oxidase, conversion to valproic acid and behavioral effects.

2-Propyl-1-aminopentane (2-PAPN), a branched aliphatic amine, was found to be readily deaminated by monoamine oxidase B in the liver of the rat and semicarbazide-sensitive amine oxidase in the aorta of the rat. The deaminated product, 2-propyl-1-pentaldehyde, could be subsequently converted to valproic acid in the presence of aldehyde dehydrogenase and beta-NAD cofactor in vitro as well as in vivo. Valproic acid was identified after derivatization with 4-bromomethyl-6,7-dimethoxycoumarin, followed by HPLC-fluorometric assessment. Absorption and biotransformation of a single intraperitoneal dose of 2-PAPN resulted in the rapid appearance of the drug and its metabolite in the blood and in the brain. The formation of valproic acid from 2-PAPN in vivo, however, was insufficient to facilitate anticonvulsant action. In fact, 2-PAPN itself, at relatively small doses, exhibited distinct tremor effects. Such tremor effects could be prevented by valproic acid. However, 2-PAPN was also found to potentiate the convulsant effect induced by mercaptopropionic acid (MPA) and, in addition, the 2-PAPN-induced tremor could be potentiated by MPA in mice.

Amines↗
PubMed2005

Alternative oxidase and plastoquinol terminal oxidase in marine prokaryotes of the Sargasso Sea.

Alternative oxidase (AOX) represents a non-energy conserving branch in mitochondrial electron transport while plastoquinol terminal oxidase (PTOX) represents a potential branch in photosynthetic electron transport. Using a metagenomics dataset, we have uncovered numerous and diverse AOX and PTOX genes from the Sargasso Sea. Sequence similarity, synteny and phylogenetic analyses indicate that the large majority of these genes are from prokaryotes. AOX appears to be widely distributed among marine Eubacteria while PTOX is widespread among strains of cyanobacteria closely related to the high-light adapted Prochlorococcus marinus MED4, as well as Synechococcus. The wide distribution of AOX and PTOX in marine prokaryotes may have important implications for productivity in the world's oceans.

Amino Acid Motifs↗
PubMed2004

Attenuated Salmonella typhimurium htrA mutants cause fatal infections in mice deficient in NADPH oxidase and destroy NADPH oxidase-deficient macrophage monolayers.

Salmonella live vaccine strains harbouring mutations in htrA, a stress protein gene, display increased susceptibility to oxidative stress in vitro. This is believed to be connected to their reduced virulence, perhaps due to impaired survival inside phagocytes, although this has never been formally proven. We report that the in vitro phenotype of increased susceptibility to oxidative stress of Salmonella typhimurium htrA mutants newly prepared by transduction is rapidly lost on subculture, with the mutants becoming as resistant as the parent for reasons that remain unclear. However, despite this change, htrA mutants are still attenuated in normal mice. In contrast, they were found to be lethal for gene targeted gp91phox-/- mice deficient in NADPH oxidase, as was a S. typhimurium SPI-2 mutant known to be virulent in gp9lphox-/- mice. Infection with htrA mutants caused little damage to primary bone marrow macrophage cultures from normal mice; conversely, they caused extensive damage to macrophages from gp9lphox-/- mice, with more than 60% reduction in cell numbers 2.5h after being infected. The parental wild type strain similarly caused extensive damage to macrophages from both normal and gp9lphox-/- mice, whereas an aroA live vaccine strain had no effect on either normal or gp9lphox-/- macrophages. Taken collectively, the present results suggest that htrA is somehow involved in resistance to oxidative stress in vivo, with the avirulence of htrA mutants in mice being due to mechanisms which involve NADPH oxidase and suppression of bacterial growth within macrophages.

Animals↗
PubMed1988

Partial amino acid sequence analysis of human placenta monoamine oxidase A and bovine liver monoamine oxidase B.

We have prepared peptide maps from human placenta monoamine oxidase type A (MAO-A) and bovine monoamine oxidase type B (MAO-B) and determined the amino acid sequences of 21 of these peptides. These sequences have been compared to the cDNA deduced amino acid sequences of human MAO-A and -B. A result of special interest is the identification of two sets of MAO-A peptides which have sequences different from those deduced from cDNA sequences. This observation is consistent with the notion that MAO-A may be composed of at two subunits which are similar but not identical in primary amino acid sequence.

Amino Acid Sequence↗
PubMed1979

Simultaneous occurrence of xanthine oxidase and sulfite oxidase deficiency. A molybdenum dependent inborn error of metabolism?

In a 3-week old female child with clinical features including neurologic abnormalities and lens dislocation, xanthinuria co-existed with increased excretion of sulfur compounds (sulfite, S-sulfocysteine, taurine and thio-sulfate). Low xanthine oxidase and absent sulfite oxidase activities were found on liver biopsy. No abnormality was detected in either parent. Both the above enzymes are molybdenum-flavoproteins. Normal serum molybdenum concentration seemed to rule out dietary deficiency or impaired absorption. A defect in the incorporation of the metal into flavoproteins is postulated in this case.

Animals↗