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PubMed1983

Quantitation of immunoadsorbed flavoprotein oxidases by luminol-mediated chemiluminescence.

The detection of the flavoenzymes 6-hydroxy-L-nicotine oxidase and 6-hydroxy-D-nicotine oxidase at the sub-femtomol level was achieved by coupling the reaction of the immunoadsorbed proteins to the peroxidase-catalysed oxidation of luminol. The H2O2-producing oxidases retained their full activity when bound to the respective immobilized antibodies. This fact allowed the concentration of the enzymes from very dilute solutions and the quantitative assay of their activities in the microU range. Due to strict stereoselectivity and the absence of immunological cross-reactivity, the two flavoproteins could be determined in the same solution. This method was used to measure the 6-hydroxy-D-nicotine oxidase and 6-hydroxy-L-nicotine oxidase activities in Escherichia coli RR1 and different Arthrobacter strains cultured under non-inducing conditions. The same activity ratio of 6-hydroxy-L-nicotine oxidase/6-hydroxy-D-nicotine oxidase as in D L-nicotine-induced cells of A. oxidans was observed in non-induced wild type and in riboflavin-requiring (rf-) mutant cells of this aerob.

Antigen-Antibody Complex↗
PubMed1996

NAD(P)H-dependent production of oxygen reactive species by the salivary glands of the mosquito Anopheles albimanus.

Salivary gland homogenates of the adult female mosquito Anopheles albimanus, but not those of Aedes aegypti, induced light production in the presence of NADPH and luminol, indicating a NADPH oxidase activity producing reactive oxygen species (superoxide anion) by the anopheline salivary homogenate. Superoxide production by the anopheline salivary homogenate was also confirmed by the NADPH-dependent, superoxide dismutase inhibitable, reduction of cytochrome c. The NADPH oxidase reaction measured by light production in the presence of luminol was inhibited by superoxide dismutase and catalase. Both NADH and NADPH were substrates for the production of oxygen reactive species by the salivary homogenate. Activity, as measured by luminol-dependent light emission, was enhanced one order of magnitude in the presence of 1.6 mg/ml of either phosphatidylserine or bovine serum albumin. Molecular sieving and hydroxyapatite chromatography of the salivary homogenate showed coelution of the NADPH oxidase activity with the previously reported salivary peroxidase activity. It is suggested that the salivary peroxidase of Anopheles albimanus has the ability of producing superoxide in the presence of NADPH, and this may provide the peroxidase with substrates necessary for peroxidation of vasoconstrictor amines such as serotonin, released by aggregating platelets at the site of mosquito probing and feeding.

Aedes↗
PubMed2003

Activities of xanthine oxidoreductase and antioxidant enzymes in different tissues of diabetic rats.

Oxidative stress is an important pathogenic constituent in diabetic endothelial dysfunction. The aim of this study was to investigate whether an increase in oxidative stress related to xanthine oxidoreductase occurs in diabetes. Liver, brain, heart, and kidney xanthine oxidase (XO), xanthine dehydrogenase (XDH), antioxidant enzymes (glutathione peroxidase, superoxide dismutase, catalase), and nitrite levels were measured in control and early and late diabetic rat models. Although diabetes had no impact on liver XO and XDH activity, XDH activity in heart, kidney, and brain was significantly greater in late diabetic rats than in controls. Selenium glutathione peroxidase (GPx) activity was found to be lower in the liver, brain, kidney, and heart of late diabetic rats than in controls. The measured decrease in selenium GPx activity was also observed in early diabetic heart, kidney, and brain. No significant change was observed in liver, brain, and kidney copper/zinc superoxide dismutase (Cu/Zn SOD) activity in early and late diabetic rat models compared with that in controls, whereas heart Cu/Zn SOD activity was significantly decreased in both early and late diabetic rats. Liver and brain catalase activity remained similar among the different experimental groups, whereas increased heart and kidney catalase activity was observed in both early and late diabetic rats. Liver, kidney, and brain nitrite levels were found to be increased in early diabetic rat models compared with those in controls. These data suggest that the increased XDH and decreased selenium GPx activity observed in the later stages of diabetes leads to enhanced oxidative stress in the heart, kidney, and brain, resulting in secondary organ damage associated with the disease.

Animals↗
PubMed1978

[Changes in peroxidation under conditions of 3,4-benzypyrene-induced carcinogenesis].

The activities of enzymatic systems generating and destroying peroxides and the lipid peroxide content in neoplastic rat liver and 3,4-benzpyrene-induced sarcoma were studied. The tumour was characterized by high activity of glutathione peroxidase and low activity of catalase. No urate- and glycolate oxidases or ascorbat dependent peroxidation of lipids and lipid peroxides were found in the tumour. In the liver of neoplastic animals the activities of glutathione peroxidase and NADPH-dependent system of microsomal phospholipid peroxidation and the lipd peroxides content were increased, whereas the activities of catalase and urate oxidase were decreased.

Alcohol Oxidoreductases↗
PubMed2005

Characterization of the oxidase activity in mammalian catalase.

Catalase is a highly conserved heme-containing antioxidant enzyme known for its ability to degrade hydrogen peroxide into water and oxygen. In low concentrations of hydrogen peroxide, the enzyme also exhibits peroxidase activity. We report that mammalian catalase also possesses oxidase activity. This activity, which is detected in purified catalases, cell lysates, and intact cells, requires oxygen and utilizes electron donor substrates in the absence of hydrogen peroxide or any added cofactors. Using purified bovine catalase and 10-acetyl-3,7-dihydroxyphenoxazine as the substrate, the oxidase activity was found to be temperature-dependent and displays a pH optimum of 7-9. The Km for the substrate is 2.4 x 10(-4) m, and Vmax is 4.7 x 10(-5) m/s. Endogenous substrates, including the tryptophan precursor indole, the neurotransmitter precursor beta-phenylethylamine, and a variety of peroxidase and laccase substrates, as well as carcinogenic benzidines, were found to be oxidized by catalase or to inhibit this activity. Several dietary plant micronutrients that inhibit carcinogenesis, including indole-3-carbinol, indole-3-carboxaldehyde, ferulic acid, vanillic acid, and epigallocatechin-3-gallate, were effective inhibitors of the activity of catalase oxidase. Difference spectroscopy revealed that catalase oxidase/substrate interactions involve the heme-iron; the resulting spectra show time-dependent decreases in the ferric heme of the enzyme with corresponding increases in the formation of an oxyferryl intermediate, potentially reflecting a compound II-like intermediate. These data suggest a mechanism of oxidase activity involving the formation of an oxygen-bound, substrate-facilitated reductive intermediate. Our results describe a novel function for catalase potentially important in metabolism of endogenous substrates and in the action of carcinogens and chemopreventative agents.

Animals↗
PubMed2001

Role of extracellular peroxidase in the superoxide production by wheat root cells.

Extracellular peroxidase has been shown to contribute to superoxide production in wounded wheat (Triticum aestivum L. cv. Ljuba) root cells. The superoxide-synthesizing system of root cells was considerably inhibited by KCN and NaN3 and activated by MnCl2 and H2O2. Treatment of roots with salicylic acid and a range of di- and tri-carbonic acids (malic, citric, malonic, fumaric, and succinic acids) stimulated superoxide production in both root cells and extracellular solution. The H2O2-stimulated superoxide production in the extracellular solution was much higher when roots were preincubated with salicylic or succinic acid. Exogenous acids enhanced peroxidase activity in the extracellular solution. Pretreatment of root cells with the detergents trypsin and sodium dodecyl sulfate had similar effects on the peroxidase activity. Significant inhibition of both superoxide production and peroxidase activity by diphenylene iodonium suggests that the specificity of the latter as an inhibitor of NADPH oxidase is doubtful. Results obtained indicate that extra-cellular peroxidase is involved in the superoxide production in wheat root cells. The mobile form of peroxidase can be readily secreted to the apoplastic solution and serve as an emergency enzyme involved in plant wound response.

Adrenochrome↗
PubMed2002

In situ characterization of a NO-sensitive peroxidase in the lignifying xylem of Zinnia elegans.

The lignifying xylem from Zinnia elegans stems gives an intense reaction with 3,3',5,5'-tetramethylbenzidine (TMB), a reagent previously reported to be specific for peroxidase/H2O2. However, the staining of lignifying xylem cells with TMB is apparently the result of two independent mechanisms: one, the catalase-sensitive (H2O2-dependent) peroxidase-mediated oxidation of TMB, and the other, the catalase-insensitive oxidation of TMB, probably mediated by xylem oxidases which are specific from lignifying tissues. The catalase-insensitive oxidation of TMB by the Z. elegans xylem was sensitive to sodium nitroprusside (SNP), a nitric oxide (NO)-releasing compound that, when used at 5.0 mM, is capable of sustaining NO concentrations of 6.1 &mgr;M in the aqueous phase. This effect of SNP was totally reversed by 150 &mgr;M 2-phenyl-4,4,5,5-tetramethyl imidazoline-1-oxyl-3-oxide (PTIO), an efficient NO scavenger in biological systems, so the above-mentioned effect must be ascribed to NO, and not to other nitrogen oxides. This response of the catalase-insensitive TMB-oxidase activity of the lignifying Z. elegans xylem was similar to that shown by a basic peroxidase isolated from the intercellular washing fluid, which showed TMB-oxidase activity, and which was also inhibited by 5 mM SNP, the effect of SNP also being reversed by 150 &mgr;M PTIO. These results suggest that peroxidase was the enzyme responsible for the NO-sensitive catalase-insensitive TMB-oxidase activity of the lignifying Z. elegans xylem. Further support for this statement was obtained from competitive inhibitor-dissected histochemistry, which showed that this stain responded to peroxidase-selective competitive inhibitors, such as ferulic acid and ferrocyanide, in a similar way to the Z. elegans basic peroxidase. From these results, we conclude that this NO-sensitive catalase-insensitive oxidation of TMB is apparently performed by the Z. elegans basic peroxidase, and that the regulation of this enzyme by NO may constitute an intrinsically programmed event during the differentiation and death of the xylem.

Journal Article↗
PubMed1970

The function of subcellular fractions in the oxidation of glutathione in rat liver homogenate.

1. The aerobic loss of GSH added to the supernatant fraction from rat liver is much increased by including the microsome fraction, which both inhibits the concurrent reduction of the GSSG formed and also augments the net oxidation rate. 2. Oxidation occurs with a mixture of dialysed supernatant and a protein-free filtrate; the latter is replaceable by hypoxanthine and the former by xanthine oxidase, whereas fractions lacking this enzyme give no oxidation. 3. In all these instances augmentation occurs with microsomes, with fractions having urate oxidase activity and with the purified enzyme; uric acid and microsomes alone also support the oxidation. 4. Evidence implicating additional protein factors is discussed. 5. It is suggested that GSH oxidation by homogenate is linked through glutathione peroxidase to the reaction of endogenous substrate with supernatant xanthine oxidase and of the uric acid formed with peroxisomal urate oxidase.

Animals↗
PubMed1999

Interaction between osmotic and oxidative stress in diabetic precataractous lens: studies with a sorbitol dehydrogenase inhibitor.

Both sorbitol accumulation-linked osmotic stress and "pseudohypoxia" [increase in NADH/NAD+, similar to that in hypoxic tissues, and attributed to increased sorbitol dehydrogenase (1-iditol:NAD+ 5-oxidoreductase; EC 1.1.1.14; SDH) activity] have been invoked among the mechanisms underlying oxidative injury in target tissues for diabetic complications. We used the specific SDH inhibitor SDI-157 [2-methyl-4(4-N,N-dimethylaminosulfonyl-1-piperazino)pyrimid ine] to evaluate the role of osmotic stress versus "pseudohypoxia" in oxidative stress occurring in diabetic precataractous lens. Control and diabetic rats were treated with or without SDI-157 (100 mg/kg/day for 3 weeks). Lens malondialdehyde (MDA) plus 4-hydroxyalkenals (4-HA), MDA, GSH, and ascorbate levels, as well as the GSSG/GSH ratios, were similar in SDI-treated and untreated control rats, thus indicating that SDI-157 was not a prooxidant. Intralenticular osmotic stress, manifested by sorbitol levels, was more severe in SDI-treated diabetic rats (38.2+/-6.8 vs 21.2+/-3.5 micromol/g in untreated diabetic and 0.758+/-0.222 micromol/g in control rats, P<0.01 for both), while the decrease in the free cytosolic NAD+/NADH ratio was partially prevented (120+/-16 vs 88+/-11 in untreated diabetic rats and 143+/-13 in controls, P<0.01 for both). GSH and ascorbate levels were decreased, while MDA plus 4-HA and MDA levels were increased in diabetic rats versus controls; both antioxidant depletion and lipid aldehyde accumulation were exacerbated by SDI treatment. Superoxide dismutase (superoxide:superoxide oxidoreductase; EC 1.15.1.1), GSSG reductase (NAD[P]H:oxidized-glutathione oxidoreductase; EC 1.6.4.2), GSH transferase (glutathione S-transferase; EC 2.5.1.18), GSH peroxidase (glutathione:hydrogen-peroxide oxidoreductase; EC 1.11.1.9), and cytoplasmic NADH oxidase activities were increased in diabetic rats versus controls, and all the enzymes but GSH peroxidase were up-regulated further by SDI. In conclusion, sorbitol accumulation and osmotic stress generated oxidative stress in diabetic lens, whereas the contribution of "pseudohypoxia" was minor. SDIs provide a valuable tool for exploring mechanisms of oxidative injury in sites of diabetic complications.

Animals↗
PubMed1995

[Properties of enzymes for enzyme immunoassay].

Enzyme selection is very important to establish enzyme immunoassay system. The appropriate enzyme selected to label an immunochemical reagent must have certain qualities as follows: 1) highly purified and high specific activity, 2) inexpensive, 3) stable during conjugation and for a long time in a proper storage condition, 4) easily conjugated, measured, and applied to highly sensitive assay. Several enzymes fulfill most of the above requirements and have been successfully used in enzyme immunoassay. These are horseradish peroxidase, alkaline phosphatase, beta-galactosidase, glucose oxidase, glucose-6-phosphate dehydrogenase, etc. As for enzyme activity measuring procedures, chemiluminescence and bioluminescence assays generally exhibit more sensitive detection limits than fluorescent or colorimetric assays. In the future, ultrasensitive luminescent assays and production of excellent recombinant enzymes are expected.

Alkaline Phosphatase↗
PubMed1994

Ascorbate radicals in fresh cow's milk.

Using ESR, a weak signal identified as the ascorbate free radical was observed in fresh cow's milk. The signal was unchanged after storage at 5 degrees C for 24 h but disappeared after storage at 25 degrees C. A marked increase in the steady-state ascorbate radical concentration was observed with the addition of H2O2 or xanthine; the increase was abolished in the presence of azide. Based on the xanthine-oxygen reductase activity and 2,2'-azino-di-(3-ethylbenzthiazoline-6-sulfonic acid) peroxidase activity, cow's milk contains 0.45 microM xanthine oxidase and 0.32 microM lactoperoxidase. The results suggest that H2O2- and xanthine-induced ascorbate radical formation was due to the ascorbate peroxidase activity of lactoperoxidase in cow's milk.

Animals↗
PubMed1986

Determination of amine oxidases in tissues by peroxidation-induced chemiluminescence of phthalazines.

A method is proposed for the determination of the activity of amine oxidases in purified samples and tissue homogenates. The method is based on the chemiluminescence of luminol and other cyclic hydrazides elicited by the horseradish peroxidase-catalyzed peroxidation using H2O2 produced in the amine oxidase reaction. Several aspects of the chemiluminescence method for determining enzymatic activity in crude tissue extracts are discussed.

Animals↗
PubMedDate not supplied

Lipid peroxidation and some antioxidant enzymes in nasal polyp tissue.

Nasal polyp (NP) is considered an inflammatory condition in nasal and paranasal sinus cavities and is frequently encountered in otolaryngology clinics. Although the pathophysiology of nasal polyps is poorly understood, it seems likely that the epithelium may play a critical role in the genesis of inflammatory nasal disease. The aim of this study was to investigate the role of free radicals and antioxidant enzymes in NP and compare these findings with concha bullosa (CB). NP and CB were obtained from 27 and 23 patients, respectively. Glutathione peroxidase (GSH-Px), catalase (CAT), xanthine oxidase (XO) total (enzymic plus non-enzymic) superoxide scavenger activity (TSSA), non-enzymic superoxide scavenger activity (NSSA), superoxide dismutase (SOD), and MDA levels in NP and CB were measured. GSH-Px activiy was significantly lower in patients with NP than in the CB group. However, CAT, XO activities and MDA levels were significantly higher in patients with NP than in the CB group, but TSSA, NSSA and SOD activities were unchanged. Increases in the levels of tissue MDA in patients with NP compared to the CB group may indicate the presence of free radical damage in patients with nasal NP.

Adult↗
PubMed1987

Relationship of bacterial growth phase to killing of Listeria monocytogenes by oxidative agents generated by neutrophils and enzyme systems.

Listeria monocytogenes, a gram-positive motile bacterium which can cause severe bacterial infection in humans, is considered to be pathogenic by virtue of its ability to resist intracellular killing. Since the mechanism of intracellular survival is poorly understood, we assessed the sensitivity of L. monocytogenes to several potent antibacterial products. Phorbol myristate acetate (PMA)-stimulated polymorphonuclear cells (PMNs) produced extracellular antibacterial products which were inhibited completely by catalase, suggesting a role for oxidative agents in this process. L. monocytogenes in logarithmic (log) growth phase resisted PMA-stimulated PMN extracellular products significantly more than L. monocytogenes in stationary (stat) growth phase or Escherichia coli (three strains) in either phase of growth. The role of oxidative agents was studied further by using xanthine oxidase-xanthine, glucose oxidase-glucose, and myeloperoxidase enzyme systems to generate hydroxyl radical (.OH), hydrogen peroxide (H2O2), and hypochlorous acid (OCl-), respectively. L. monocytogenes in log phase resisted the antibacterial products of these enzyme systems under conditions which produced superoxide (O2-) and H2O2 at concentrations similar to those produced extracellularly by PMA-stimulated PMNs, while stat-growth-phase L. monocytogenes and E. coli in either phase of growth were susceptible. Antibacterial activity could be blocked or inhibited by exogenous catalase (for all oxygen radical-generating systems), mannitol, or desferoxamine (for xanthine oxidase-xanthine) and alanine (for myeloperoxidase), suggesting that .OH and OCl- were responsible for this activity. Log-phase L. monocytogenes had 2.5-fold higher bacteria-associated catalase activity, as compared with stat-phase L. monocytogenes. These experiments, therefore, suggest that log-phase L. monocytogenes resists oxidative antibacterial agents by producing sufficient catalase to inactivate these products. This may contribute to the ability of L. monocytogenes to survive intracellularly.

Blood Bactericidal Activity↗
PubMed1996

Ultraviolet-B- and ozone-induced biochemical changes in antioxidant enzymes of Arabidopsis thaliana.

Earlier studies with Arabidopsis thaliana exposed to ultraviolet B (UV-B) and ozone (O3) have indicated the differential responses of superoxide dismutase and glutathione reductase. In this study, we have investigated whether A. thaliana genotype Landsberg erecta and its flavonoid-deficient mutant transparent testa (tt5) is capable of metabolizing UV-B- and O3-induced activated oxygen species by invoking similar antioxidant enzymes. UV-B exposure preferentially enhanced guaiacol-peroxidases, ascorbate peroxidase, and peroxidases specific to coniferyl alcohol and modified the substrate affinity of ascorbate peroxidase. O3 exposure enhanced superoxide dismutase, peroxidases, glutathione reductase, and ascorbate peroxidase to a similar degree and modified the substrate affinity of both glutathione reductase and ascorbate peroxidase. Both UV-B and O3 exposure enhanced similar Cu,Zn-superoxide dismutase isoforms. New isoforms of peroxidases and ascorbate peroxidase were synthesized in tt5 plants irradiated with UV-B. UV-B radiation, in contrast to O3, enhanced the activated oxygen species by increasing membrane-localized NADPH-oxidase activity and decreasing catalase activities. These results collectively suggest that (a) UV-B exposure preferentially induces peroxidase-related enzymes, whereas O3 exposure invokes the enzymes of superoxide dismutase/ascorbate-glutathione cycle, and (b) in contrast to O3, UV-B exposure generated activated oxygen species by increasing NADPH-oxidase activity.

Antioxidants↗
PubMed1994

Secretion of Ligninolytic Enzymes and Mineralization of C-Ring-Labelled Synthetic Lignin by Three Phlebia tremellosa Strains.

Production of ligninolytic enzymes by three strains of the white rot fungus Phlebia tremellosa (syn. Merulius tremellosus) was studied in bioreactor cultivation under nitrogen-limiting conditions. The Mn(II) concentration of the growth medium strongly affected the secretion patterns of lignin peroxidase and laccase. Two major lignin peroxidase isoenzymes were expressed in all strains. In addition, laccase and glyoxal oxidase were purified and characterized in one strain of P. tremellosa. In contrast, manganese peroxidase was not found in fast protein liquid chromatography profiles of extracellular proteins under either low (2.4 muM) or elevated (24 and 120 muM) Mn(II) concentrations. However, H(2)O(2)- and Mn-dependent phenol red-oxidizing activity was detected in cultures supplemented with higher Mn(II) levels. Mineralization rates of C-ring-labelled synthetic lignin (i.e., dehydrogenation polymerizate) by all strains under a low basal Mn(II) level were similar to those obtained for Phanerochaete chrysosporium and Phlebia radiata. A high manganese concentration repressed the evolution of CO(2) even when a chelating agent, sodium malonate, was included in the medium.

Journal Article↗