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PubMed1992

A specific peroxidase-coupled activity stain for diamine oxidases.

A specific peroxidase-coupled activity staining method for diamine oxidase (DAO) was developed. Diaminobenzidine was found to inhibit DAO and to give rise to unspecific staining. Among several other reagents 4-Cl-1-naphthol was found to be most suitable. Using specific activity staining DAO could be visualized in polyacrylamide gels as a high-molecular-weight complex, which could be dissociated by Tween 20 but not by NP-40, Triton X-100, or Chaps.

3,3'-Diaminobenzidine↗

PubMed1986

Localization of cytochrome C oxidase and cytochrome C peroxidase in mitochondria of Hymenolepis diminuta (Cestoda).

The intramitochondrial localization of cytochrome c oxidase and cytochrome c peroxidase in adult Hymenolepis diminuta was investigated. Mitochondria were fractionated into inner membrane, outer membrane, intermembrane space and matrix and the efficacy of fractionation was monitored employing marker enzymes. Cytochrome c oxidase was associated with the mitochondrial inner membrane. Whereas 55% of the cytochrome c peroxidase activity was in the matrix, 32% of the activity was in the intermembrane space fraction. Based upon the distribution of marker enzymes, a dual compartmentalization of cytochrome c peroxidase is apparent in H. diminuta mitochondria.

Animals↗

PubMed1992

On the mechanism of inhibition of the veratryl alcohol oxidase activity of lignin peroxidase H2 by EDTA.

The mechanism of inhibition of the veratryl alcohol oxidase activity of lignin peroxidase H2 (LiPH2) by EDTA was investigated. It was found that EDTA was decarboxylated and that cytochrome c, nitro blue tetrazolium, ferric iron, and molecular oxygen were reduced in a reaction mixture containing LiPH2, H2O2, veratryl alcohol, and EDTA. The reductive activity observed with LiPH2 followed first order kinetics with respect to the concentration of EDTA. Stoichiometry studies showed that in the presence of sufficient EDTA, 1.7 mol of ferric iron were reduced per mole of H2O2 added to the reaction mixture. Superoxide- and EDTA-derived radicals were detected by ESR spin trapping upon incubation of LiPH2 with H2O2, veratryl alcohol, and EDTA. The Km values of veratryl alcohol and H2O2 remained the same for both the oxidative and reductive activities of LiPH2. Reductive activity was also observed with LiPH2 and EDTA using other free radical mediators in the place of veratryl alcohol, such as 1,4-dimethoxybenzene, 1,2,3- and 1,2,4-trimethoxybenzenes, and 1,2,4,5-tetramethoxybenzene. EDTA reduced the cation radical of 1,2,4,5-tetramethoxybenzene formed by LiPH2 in the presence of H2O2. Hence, it is proposed that the apparent inhibition of the veratryl alcohol oxidase activity of LiPH2 by EDTA is due to the reduction of the veratryl alcohol cation radical intermediate back to veratryl alcohol by EDTA. The reduction of cytochrome c, nitro blue tetrazolium, ferric ion, and molecular oxygen appears to be mediated by the EDTA radical formed by reduction of the veratryl alcohol cation radical.

Alcohol Oxidoreductases↗

PubMed1997

Proton pumping by cytochrome c oxidase is coupled to peroxidase half of its catalytic cycle.

The four-electron reaction cycle of cytochrome oxidase is comprised of an eu-oxidase phase in which the enzyme receives the first two electrons and reduces oxygen to bound peroxide and a peroxidase phase in which the peroxy state formed in the eu-oxidase half of the cycle is reduced by the 3rd and 4th electrons to the ferryl-oxo state and oxidized form, respectively. Here we show that the ferrocyanide-peroxidase activity of cytochrome c oxidase incorporated in phospholipid vesicles is coupled to proton pumping. The H+/e- ratio for the ferrocyanide-peroxidase partial reaction is twice higher than for the overall ferrocyanide-oxidase activity and is close to 2. These results show that proton pumping by COX is confined to the peroxidase part of the enzyme catalytic cycle (transfer of the 3rd and 4th electron) whereas the eu-oxidase part (transfer of the first two electrons) may not be proton pumping.

Animals↗

PubMed1994

A general method for immobilization of glycoproteins on regenerable immobilized metal-ion carriers: application to glucose oxidase from Penicillium chrysogenum and horseradish peroxidase.

A general method for immobilization of glycoproteins on immobilized metal-ion carriers is described. The method includes oxidation of the carbohydrate moiety of the glycoprotein with potassium periodate, covalent modification with histidine and immobilization on bivalent metal ion-iminodiacetic acid-agarose. The method is exemplified with horseradish peroxidase and glucose oxidase from Penicillium chrysogenum. The modified and immobilized enzymes are stable for at least 2 months at 4 degrees C. The immobilized enzymes were used as enzyme electrodes for the determination of the glucose concentration.

Biosensing Techniques↗

PubMed2003

Bienzyme biosensors for glucose, ethanol and putrescine built on oxidase and sweet potato peroxidase.

Amperometric biosensors for glucose, ethanol, and biogenic amines (putrescine) were constructed using oxidase/peroxidase bienzyme systems. The H(2)O(2) produced by the oxidase in reaction with its substrate is converted into a measurable signal via a novel peroxidase purified from sweet potato peels. All developed biosensors are based on redox hydrogels formed of oxidases (glucose oxidase, alcohol oxidase, or amine oxidase) and the newly purified sweet potato peroxidase (SPP) cross-linked to a redox polymer. The developed electrodes were characterized (sensitivity, stability, and performances in organic medium) and compared with similarly built ones using the 'classical' horseradish peroxidase (HRP). The SPP-based electrodes displayed higher sensitivity and better detection limit for putrescine than those using HRP and were also shown to retain their activity in organic phase much better than the HPR based ones. The importance of attractive or repulsive electrostatic interactions between the peroxidases and oxidases (determined by their isoelectric points) were found to play an important role in the sensitivity of the obtained sensors.

Alcohol Oxidoreductases↗

PubMed1982

The cytochrome c peroxidase activity of cytochrome oxidase.

I have found that mammalian cytochrome oxidase catalyzes the peroxidatic oxidation of ferrocytochrome c under strictly anaerobic conditions. An apparent Km value for ferrocytochrome c was 2 microM, and a second order rate constant, estimated as an extrapolated value, was 1.4 X 10(6) M-1 s-1 at pH 7.4 at 25 degrees C. These values were quite similar to the corresponding values of 6.4 microM and 1.9 X 10(6) M-1 s-1 determined for the intrinsic oxidase activity. The rate of the peroxidatic oxidation showed a hyperbolic dependence on the concentration of hydrogen peroxide, and the apparent Km value ws 0.18 mM. Cyanide and azide at 0.1 mM inhibited the peroxidase activity by 100 and 98%, respectively, whereas, under carbon monoxide at 750 mm Hg, 10% of the activity still remained. Under air, cytochrome oxidase acted simultaneously as oxidase and peroxidase.

Animals↗

PubMed2004

Adenosine deaminase, xanthine oxidase, superoxide dismutase, glutathione peroxidase activities and malondialdehyde levels in the sera of patients with head and neck carcinoma.

OBJECTIVES: Clinical and epidemiological findings have provided evidence supporting a role of free radicals in the etiology of cancer. Scavengers and inhibitors of free radical processes have been demonstrated to prevent or delay the neoplastic process. PATIENTS AND METHODS: Adenosine deaminase, xanthine oxidase, superoxide dismutase, and glutathione peroxidase activities and malondialdehyde levels were measured in the sera of 35 patients with head and neck cancers and were compared to those of healthy control subjects. RESULTS: Serum adenosine deaminase activity was found to be significantly increased in the patient group (p<0.001). Compared to the control group, glutathione peroxidase and xanthine oxidase activities and malondialdehyde levels were slightly higher and serum superoxide dismutase activity was slightly lower in the patient group, with none reaching statistical significance. CONCLUSION: The results indicate that serum adenosine deaminase activity may be helpful in the diagnosis and follow-up of head and neck cancers. Further studies with a larger cohort of patients are needed to clarify the exact mechanism of adenosine deaminase elevation.

Adenosine Deaminase↗

PubMed1984

Colorimetric assay for monoamine oxidase in tissues using peroxidase and 2,2'-azinodi(3-ethylbenzthiazoline-6-sulfonic acid) as chromogen.

Monoamine oxidase is assayed in tissue by a colorimetric reaction using horse radish peroxidase and 2,2'-azinodi(ethylbenzthiazoline-6-sulfonic acid to measure H2O2 formed during oxidation of amines. The method has a coefficient of variation of approximately 2.5% and provides results comparable with those of radiometric assay. Monoamine oxidase activities in rat liver mitochondria and crude mitochondrial fraction from brain and with tyramine as a substrate were 18.9 +/- 0.4 and 4.61 +/- 0.15 nmol/min/mg of protein, respectively, using this method. Kinetic parameters of liver and brain monoamine oxidase with various substrates and inhibitors appeared to be the same when determined by either colorimetric or radiometric methods.

Animals↗

PubMed2004

Microfluidic biosensing systems. Part II. Monitoring the dynamic production of glucose and ethanol from microchip-immobilised yeast cells using enzymatic chemiluminescent micro-biosensors.

A microfluidic flow injection (microFIA) system was employed for handling and monitoring of cell-released products from living cells immobilised on silicon microchips. The dynamic release of glucose and ethanol produced from sucrose by immobilised Saccharomyces cerevisiae cells was determined using microchip biosensors (micro-biosensors) with either co-immobilised glucose oxidase-horseradish peroxidase (GOX-HRP), or alcohol oxidase-horseradish peroxidase (AOX-HRP), catalysing a series of reactions ending up with chemiluminescence (CL) generated from HRP-catalysed oxidation of luminol in presence of p-iodophenol (PIP). The yeast cells were attached by first treating them with polyethylenimine (PEI) followed by adsorption to the microchip surface. The cell loss during assaying was evaluated qualitatively using scanning electron microscopy (SEM), showing that no cells were lost after 35 min liquid handling of the cell chip at 10 microl min(-1). The enzymes were immobilised on microchips via PEI-treatment followed by glutaraldehyde (GA) activation. The GOX-HRP micro-biosensors could be used during five days without any noticeable decrease in response, while the AOX-HRP micro-biosensors showed continuously decreasing activity, but could still be used employing calibration correction. The glucose and ethanol released from the immobilised yeast chips were quantitatively monitored, by varying the incubation time with sucrose, showing the possibilities and advantages of using a microfluidic system set-up for cell-based assays.

Biosensing Techniques↗

PubMed1988

Immobilization of enzymes on polypropylene bead surfaces by anhydrous ammonia gaseous plasma technique.

Anhydrous ammonia gaseous plasma technique was used for the surface modification of polypropylene beads. Amino groups were added onto the surfaces of beads by exposing them to ammonia plasma. Through these amino groups covalent immobilization of glucose oxidase and peroxidase were carried out. The total amounts of immobilized glucose oxidase and immobilized peroxidase were found to be 52 and 43 micrograms/cm2, respectively. To assess the stability of enzyme-polypropylene linkage, beads with covalently immobilized glucose oxidase and peroxidase were washed with phosphate buffer. It was found that after the removal of the adsorbed enzymes, the concentration of covalently immobilized enzymes tended to reach a steady state. After additional washing with buffer for 5 to 6 h, 40-55% of the immobilized enzymes were found to be in the active form.

Ammonia↗

PubMed2003

An improved method for the determination of NADH oxidase in the presence of NADH peroxidase in lactic acid bacteria.

The complexity of the coupled NADH oxidase-NADH peroxidase enzyme system in lactic acid bacteria makes it difficult to simultaneously determine the individual levels of both these enzymes spectrophotometrically. This study describes an improved assay to accurately determine low concentrations of NADH oxidase from enzyme suspensions containing NADH oxidase and NADH peroxidase. For the standardisation of the assay, pure NADH oxidase and NADH peroxidase were mixed in various proportions and the percentage recovery was estimated by both the currently available assay as well as by the improved assay reported in this study. The recovery of NADH oxidase using the currently available assay ranged from as low as -200% to as high as +102% as against 90-102% in the improved assay. The recovery percentage of NADH peroxidase ranged from 91% to 112% in both assays. The slopes of NADH oxidation by cell-free extracts of six lactic acid bacteria were also measured by both assays for the estimation of NADH oxidase and NADH peroxidase levels. The improved assay can further distinguish between NADH-H(2)O oxidase and NADH-H(2)O(2) oxidase and was successfully applied to identify the type of NADH oxidase in the lactic acid bacteria tested.

Bacteria↗

PubMed1979