Catalytic Activity Of Catalase Research Articles

Toxicity evaluation of iron oxide nanoparticles to freshwater cyanobacteria Nostoc ellipsosporum.

The extensive usage of iron oxide nanoparticles (FeO NPs) in commercial and biomedical applications raises the risk of releasing their remains into the aquatic ecosystems and this could possibly cause cytotoxic effects on aquatic organisms. Thus, the toxicity assessment of FeO NPs on cyanobacteria, which are primary producers at the bottom of food chain in aquatic ecosystems, is essential to gain information about the potential ecotoxicological threat on aquatic biota. The present study investigated the cytotoxic effects of FeO NPs on Nostoc ellipsosporum using different concentrations (0, 10, 25, 50 and 100mg L-1) to track the time-dependent and dose-dependent effects and compared with its bulk equivalent. In addition, the impacts of FeO NPs and bulk counterpart on cyanobacterial cells were assessed under nitrogen as well as nitrogen-deficient conditions, because of ecological role of cyanobacteria in nitrogen fixation. The study revealed that the highest protein content was observed in the control in both types of BG-11 media compared to treatments of nano and bulk particles of Fe2O3. A 23% reduction in protein in nanoparticle treatment and a 14% reduction in bulk treatment at 100mg L-1 was observed in BG-11 medium. At same concentration, in BG-110 media, this decline was even more intense with 54% reduction in nanoparticle and a 26% reduction in bulk. Catalytic activity of catalase and superoxide dismutase was found to be linearly correlated with the dose concentration for nano and bulk form in BG-11 as well as BG-110 media. The increased levels of lactate dehydrogenase act as biomarker of the cytotoxicity brought on by nanoparticles. Optical, scanning electron, and transmission electron microscopy all demonstrated the cell entrapment, nanoparticle deposition on the cell surface, cell wall collapse and membrane degradation. A cause for concern is that nanoform was found to be more hazardous than bulk form.

Theoretical Study on Cobalt Ferrite ConFe3−nO4 (n = 1–2) Nanoparticles with Multi-enzyme Activities

Through on the basis of density functional theory calculations (DFT), harmonic transition state theory and d-band center theory, the reaction mechanism and catalytic activity of Catalase, Superoxide dismutase and Peroxidase activities on the ConFe3−nO4 (n = 1–2) are systematically investigated. The results show that CoFe2O4 is the most stable catalyst with the best catalytic effect. For the simulated activity of catalase, we find that the path-3 (H* and HO* → H2O) is the best on CoFe2O4 and Co2FeO4. For the simulated activity of superoxide dismutase, the path HOO* + HOO → H2O2 + O2 is optimal on CoFe2O4 and Co2FeO4. For the simulated activity of peroxidase, the mechanism on CoFe2O4 and Co2FeO4 is OOH* + H* → H2O + O*, O* + TMB → OH* + oxTMB, OH* + TMB → H2O + oxTMB. The results of these methods are consistent. The results thus provide an in-depth insight into the reaction mechanism and activity of ConFe3−nO4 as catalase, superoxide dismutase and peroxidase mimics and may play a role in the application of nanoparticles as mimics.

Experimental investigation and molecular dynamics simulation of the binding of ellagic acid to bovine liver catalase: Activation study and interaction mechanism

Ellagic acid (ELA), as a polyphenolic natural compound and food additive, which has reported to possess anti-carcinogenic, antioxidant, antidepressant, ameliorative and anti-mutagenic effects. In the current work, the effects of ELA on the conformation and catalytic activity of catalase were investigated by using spectroscopic techniques including ultraviolet visible (UV–vis), fluorescence, synchronous fluorescence and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy as well as molecular dynamics (MD) simulation. Kinetic studies showed that the enzymatic activity of catalase increases in the presence of ELA (almost 2-fold higher than free enzyme activity). Moreover, analysis of fluorescence data revealed two binding sites for ELA on the catalase and static type of quenching mechanism. The binding constants between ELA and catalase were obtained to be 47.35 × 107 M−1 (at 298 K) and 17.60 × 107 M−1 (at 310 K) and the binding distance was calculated to be 2.83 nm. Thermodynamic data showed that hydrogen bonds have a main role in the ELA-catalase complex formation. The best binding sites for ELA were, in the middle of β-barrel and wrapping domain and in the middle of β-barrel and helical domain, according to molecular docking data. MD simulation results were confirmed that ELA can increase catalase activity through increasing the distance between an upper side α-helix structure and a down side random coil structure.

Role of Active Site Residues on Catalytic Activity of Catalase with Oxidase Activity from Scytalidium Thermophilum

Scytalidium thermophilum produces a catalase with phenol oxidase activity (CATPO) that catalyses the dismutation of hydrogen peroxide (H2O2) to dioxygen and water and also oxidizes several phenolic compounds in the absence of hydrogen peroxide. It comprises 717 amino acids with a 19 amino acid signal sequence, and a 17 amino acid prosequence. It is a homotetrameric protein of molecular mass 320 kDa and subunit molecular mass 80 kDa. Although catalases have been studied for many years, a peroxide independent oxidative activity of catalases has recently been recognized. There are a great number of reports available describing the structural and biochemical characterization of catalases. However basic questions related to substrate and product flow remain unanswered, particularly related to the oxidase activity. The goals of our current studies are to investigate the main and lateral channels known that connect the deeply buried active site to the exterior of the enzyme. We have introduced a number of mutations into these regions and analyzed their specific activities.

Effect of dose and dose rate of gamma radiation on catalytic activity of catalase

Catalytic activity of gamma irradiated catalase from bovine liver was studied for hydrogen peroxide decomposition at constant temperature and pressure. The measurement was performed at temperatures 27, 32, 37, 42 and 47 °C. Solutions containing 1 and 0.01 g dm−3 of catalase in phosphate buffer were used for the study. Repeatability of both sample preparation and kinetics measurement was experimentally verified. Rate constants of the reaction were determined for all temperatures and the activation energy was evaluated from Arrhenius plot. Gamma irradiation was performed using 60Co radionuclide source Gammacell 220 at two different dose rates 5.5 and 70 Gy h−1, with doses ranging from 10 to 1000 Gy. The observed reaction of irradiated and non-irradiated catalase with hydrogen peroxide is of the first order. Irradiation significantly decreases catalytic activity of catalase, but the activation energy does not depend markedly on the dose. The effect of irradiation is more significant at higher dose rate.

Enzyme Activity of Catalase Immobilized in Langmuir−Blodgett Films of Phospholipids

A major challenge for producing low cost biosensors based on nanostructured films with control of molecular architectures is to preserve the catalytic activity of the immobilized biomolecules. In this study, we show that catalase (HRP) keeps its activity if immobilized in Langmuir-Blodgett (LB) films of dipalmitoyl phosphatidylglycerol (DPPG). The incorporation of catalase into a DPPG monolayer at the air-water interface was demonstrated with surface pressure and surface potential isotherms, in addition to polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS). According to the PM-IRRAS data, catalase was not denatured upon adsorption on a preformed DPPG monolayer and could be transferred onto a solid substrate. The catalytic activity of catalase in a mixed LB film with DPPG was ca. 13% higher than in solution. The control of molecular architecture and choice of a suitable phospholipid matrix allows catalase-containing LB films to be used in sensing hydrogen peroxide.

Enzyme-catalyzed decomposition of dibenzoyl peroxide in organic solvents.

Catalytic activity of catalase (CAT, EC 1.11.1.6), immobilized on carbon black NORIT and soot PM-100, with respect to decomposition of dibenzoyl peroxide (BPO) in non-aqueous media (acetonitrile and tetrachloromethane), was investigated with a quantitative UV-spectrophotometrical approach. Progress of the above reaction was controlled by selected kinetic parameters: the apparent Michaelis constant (Km(app)), the specific rate constant (k(sp)), the activation energy (Ea), the maximum reaction rate (Vmax), and the Arrhenius' pre-exponential factor (Z0). Conclusions on the tentative mechanism of the catalytic process observed were drawn from the calculated values of the Gibbs energy of activation (deltaG*), the enthalpy of activation (deltaH*), and entropy of activation (deltaS*).

Magnetically disturbed activity of immobilized catalase on an electrode in hydrogen-peroxide buffer

A catalase-immobilized platinum black electrode was used to measure the catalytic decomposition of hydrogen peroxide by catalase. The superconducting current of an 8 T superconducting magnet was swept between 0 T and 8 T, and the catalase electrode's current was monitored continuously under a voltage-stabilized condition. The sensor's current changed in correspondence with the varying magnetic fields. During the magnetic field exposures, the electrode's current increased nearly 200%. The clear and reproducible increase in the electrode's current under magnetic fields indicated that the catalytic activity of catalase was disturbed under magnetic field exposure of up to 8 T and at a threshold between 1 to 2 T.

Antioxidant defense status of red blood cells of patients with β-thalassemia and Eβ-thalassemia

Anemia in β-thalassemia is caused by a combination of ineffective erythropoiesis and premature hemolysis of RBC in the peripheral circulation. Excess of the α-globin chain present in β-thalassemic RBC is mainly responsible for oxidative damage of erythrocyte membrane protein. The activities of glucose-6-phosphate dehydrogenase, glutathione reductase, glutathione peroxidase, and glutathione- S-transferase, and the catalytic activity of catalase and superoxide dismutase, and the concentrations of non-enzymic antioxidants such as reduced glutathione were measured to estimate the status of the antioxidant defense system in the erythrocytes for protection against oxidative stress. The extent of lipid peroxidation was also estimated in thalassemic erythrocytes. Significantly lower activities of reduced glutathione indicate the cell to be in a pro-oxidant state and decreased activity of catalase favors hydrogen peroxide-mediated lipid peroxidation in β-thalassemic and Eβ-thalassemic RBC.

Purification and characterization of liver catalase in acatalasemic beagle dog: comparison with normal dog liver catalase

Catalase from acatalasemic dog liver was purified to homogeneity and its properties were compared with those of normal dog liver catalase. The purified acatalasemic and normal dog liver catalases were found to have the same molecular weight (230,000 Da) and isoelectric point (p I: 6.0–6.2) and both enzymes contained four hematins per molecule. The catalytic activity of catalase from acatalasemic dog was normal. Furthermore, there was no difference between the acatalasemic and normal dog catalases in the binding affinity to NADPH (apparent K d: 0.11–0.12 μM) and in the sensitivity to oxidative stress by hydrogen peroxide, the normal substrate of catalase. The acatalasemic dog enzyme was stable only in a narrow pH range (pH 6–9) although the normal enzyme was stable in a wide pH range (pH 4–10). Acatalasemic dog liver catalase also showed a slight low thermal stability at 37°C and the heat-lability was remarkable at 45°C, compared to the normal dog enzyme. These results indicated that the acatalasemic dog catalase is catalytically normal although it is associated with an unstable molecular structure.

Catalytic activity of catalase under strong magnetic fields of up to 8 T

The question of whether or not magnetic fields affect enzymatic activity is of considerable interest in biomagnetics and biochemistry. This study focuses on whether magnetically related enzymatic activities can be affected by magnetic fields. We examined the effect of magnetic fields of up to 8 T on catalytic decomposition of hydrogen peroxide (H2O2). We observed changes in absorbance of reaction mixture of hydrogen peroxide and catalase at 240 nm, during and after magnetic field exposures. When the reaction mixture was not treated with nitrogen-gas bubbling, it was observed that the initial reaction rate of the reaction which was exposed to magnetic fields of up to 8 T was 50%–85% lower than the control data. This magnetic field effect was not observed, however, when the reaction mixture was bubbled with nitrogen gas to remove the dissolved oxygen molecules which were produced in the solution. We also measured concentration of dissolved oxygen which was produced by the decomposition of hydrogen peroxide. Dissolved oxygen concentration in the reaction mixture which was exposed to magnetic fields increased 20%–25% compared to the control solution. The results of the present study indicate that magnetic fields affect dynamic movement of oxygen bubbles which are produced in the reaction mixture by the decomposition of hydrogen peroxide, but not the catalytic activity of catalase itself.

A Study of the In Vitro Reaction of Catalase and Hemin with Organic Mercury Compounds

The relative inhibitory effect of a series of organic mercury compounds (phenylmercuric nitrate, phenylmercuric hydroxide, p -chloromercuribenzoic acid, Neohydrin, and Mercuhydrin) on the catalytic activity of catalase in vitro was studied. The inhibition is relatively less with the diuretics. Increasing the concentration of all of the mercury compounds gives greater inhibition. Spectrophotometric studies of catalase protein, Armour serum albumin and crystalline hemin were made. Interaction of the protein—SH with the organic mercury compounds does not explain the inhibition under the conditions of this study. The catalase activity of hemin is inhibited by the mercury compounds in a system completely devoid of—SH groups. The hemin itself is rapidly destroyed by the hydrogen peroxide and this reaction is also depressed by the organic mercury compounds. There is no spectroscopic evidence for a hemin-mercury or hydrogen peroxide-mercury compound. Spectroscopic and preliminary polarographic data indicate the necessity of postulating a ternary complex, hemin-hydrogen peroxide-organic mercury, which is relatively stable.