Showing papers on "Catalase published in 2007"
TL;DR: The topic of antioxidant usage and ROS is currently receiving much attention because of studies linking the use of some antioxidants with increased mortality in primarily higher-risk populations and the lack of strong efficacy data for protection against cancer and heart disease, at least in populations with adequate baseline dietary consumption.
Abstract: During normal cellular activities, various processes inside of cells produce reactive oxygen species (ROS). Some of the most common ROS are hydrogen peroxide (H(2)O(2)), superoxide ion (O(2)(-)), and hydroxide radical (OH(-)). These compounds, when present in a high enough concentration, can damage cellular proteins and lipids or form DNA adducts that may promote carcinogenic activity. The purpose of antioxidants in a physiological setting is to prevent ROS concentrations from reaching a high-enough level within a cell that damage may occur. Cellular antioxidants may be enzymatic (catalase, glutathione peroxidase, superoxide dismutase) or nonenzymatic (glutathione, thiols, some vitamins and metals, or phytochemicals such as isoflavones, polyphenols, and flavanoids). Reactive oxygen species are a potential double-edged sword in disease prevention and promotion. Whereas generation of ROS once was viewed as detrimental to the overall health of the organism, advances in research have shown that ROS play crucial roles in normal physiological processes including response to growth factors, the immune response, and apoptotic elimination of damaged cells. Notwithstanding these beneficial functions, aberrant production or regulation of ROS activity has been demonstrated to contribute to the development of some prevalent diseases and conditions, including cancer and cardiovascular disease (CVD). The topic of antioxidant usage and ROS is currently receiving much attention because of studies linking the use of some antioxidants with increased mortality in primarily higher-risk populations and the lack of strong efficacy data for protection against cancer and heart disease, at least in populations with adequate baseline dietary consumption. In normal physiological processes, antioxidants effect signal transduction and regulation of proliferation and the immune response. Reactive oxygen species have been linked to cancer and CVD, and antioxidants have been considered promising therapy for prevention and treatment of these diseases, especially given the tantalizing links observed between diets high in fruits and vegetables (and presumably antioxidants) and decreased risks for cancer.
812 citations
TL;DR: In this paper, the role of superoxide dismutases (SODs) and their derivates as mediators of inflammation was discussed and new knowledge about the role and role of the superoxide anion and its derivates was discussed.
524 citations
TL;DR: Findings suggest that H2O2 derived from glucose metabolism is one of the metabolic signals for insulin secretion, whereas oxidative stress may disturb its signaling function.
Abstract: One of the unique features of beta-cells is their relatively low expression of many antioxidant enzymes. This could render beta-cells susceptible to oxidative damage but may also provide a system that is sensitive to reactive oxygen species as signals. In isolated mouse islets and INS-1(832/13) cells, glucose increases intracellular accumulation of H2O2. In both models, insulin secretion could be stimulated by provision of either exogenous H2O2 or diethyl maleate, which raises intracellular H2O2 levels. Provision of exogenous H2O2 scavengers, including cell permeable catalase and N-acetyl-L-cysteine, inhibited glucose-stimulated H2O2 accumulation and insulin secretion (GSIS). In contrast, cell permeable superoxide dismutase, which metabolizes superoxide into H2O2, had no effect on GSIS. Because oxidative stress is an important risk factor for beta-cell dysfunction in diabetes, the relationship between glucose-induced H2O2 generation and GSIS was investigated under various oxidative stress conditions. Acute exposure of isolated mouse islets or INS-1(832/13) cells to oxidative stressors, including arsenite, 4-hydroxynonenal, and methylglyoxal, led to decreased GSIS. This impaired GSIS was associated with increases in a battery of endogenous antioxidant enzymes. Taken together, these findings suggest that H2O2 derived from glucose metabolism is one of the metabolic signals for insulin secretion, whereas oxidative stress may disturb its signaling function.
509 citations
TL;DR: The results suggest that Al3+ toxicity is associated with induction of oxidative stress in rice plants and among antioxidative enzymes SOD, Guaiacol POX and cytosolic APX appear to serve as important components of an antioxidative defense mechanism under Al 3+ toxicity.
Abstract: When seedlings of rice (Oryza sativa L.) cultivar Pant-12 were raised in sand cultures containing 80 and 160 μM Al3+ in the medium for 5–20 days, a regular increase in Al3+ uptake with a concomitant decrease in the length of roots as well as shoots was observed. Al3+ treatment of 160 μM resulted in increased generation of superoxide anion (O2
−) and hydrogen peroxide (H2O2), elevated amount of malondialdehyde, soluble protein and oxidized glutathione and decline in the concentrations of thiols (-SH) and ascorbic acid. Among antioxidative enzymes, activities of superoxide dismutase (SOD EC 1.15.1.1), guaiacol peroxidase (Guaiacol POX EC 1.11.1.7), ascorbate peroxidase (APX EC 1.11.1.11), monodehydroascorbate reductase (MDHAR EC 1.6.5.4), dehydroascorbate reductase (EC 1.8.5.1) and glutathione reductase (EC 1.6.4.2) increased significantly, whereas the activities of catalase (EC EC 1.11.1.6) and chloroplastic APX declined in 160 μM Al3+ stressed seedlings as compared to control seedlings. The results suggest that Al3+ toxicity is associated with induction of oxidative stress in rice plants and among antioxidative enzymes SOD, Guaiacol POX and cytosolic APX appear to serve as important components of an antioxidative defense mechanism under Al3+ toxicity. PAGE analysis confirmed the increased activity as well as appearance of new isoenzymes of APX in Al3+ stressed seedlings. Immunoblot analysis revealed that changes in the activities of APX are due to changes in the amounts of enzyme protein. Similar findings were obtained when the experiments were repeated using another popular rice cv. Malviya-36.
370 citations
TL;DR: Results demonstrate that peroxiredoxin 2 has a tertiary structure that facilitates reaction of the active site thiol with hydrogen peroxide while restricting its reactivity with other thiol reagents.
358 citations
TL;DR: Developments in bovine catalase indicate that serendipity and new investigative approaches can reveal unexpected features, even for an enzyme that has been studied for over 100 years.
330 citations
TL;DR: It is concluded that exogenous proline mitigates the detrimental effects of salt stress more than exogenous betaine because of its superior ability to increase the activities of antioxidant enzymes.
295 citations
TL;DR: In this article, the long-term effects of 50 microM CdCl(2) on the enzymatic and nonenzymatic antioxidative defences of pea (Pisum sativum L.) plants was studied in terms of activity, protein content and transcripts levels.
288 citations
TL;DR: In this paper, the effect of As (10.0 and 50.0 μM) on seedling growth, root anatomy, lipid peroxidation (malondialdehyde and conjugated dienes), electrolyte leakage, H2O2 content, root oxidizability and the activities of antioxidant enzymes in mung bean (Phaseolus aureus Roxb).
Abstract: Arsenic (As) toxicity and its biochemical effects have been mostly evaluated in ferns and a few higher plants. In this study, we investigated the effect of As (10.0 and 50.0 μM) on seedling growth, root anatomy, lipid peroxidation (malondialdehyde and conjugated dienes), electrolyte leakage, H2O2 content, root oxidizability and the activities of antioxidant enzymes in mung bean (Phaseolus aureus Roxb.). Arsenic significantly enhanced lipid peroxidation (by 52% at 50.0 μM As), electrolyte leakage and oxidizability in roots. However, there was no significant change in H2O2 content. Arsenic toxicity was associated with an increase in the activities of superoxide dismutase (SOD), guaiacol peroxidase (GPX) and glutathione reductase (GR). In response to 50.0 μM As, the activities of SOD and GR increased by over 60% and 90%, respectively. At 10.0 μM As, the activity of ascorbate peroxidase (APX) increased by 83%, whereas at 50.0 μM it declined significantly. The catalase (CAT) activity, on the other hand, decreased in response to As exposure, and it corresponded to the observed decrease in H2O2 content. We conclude that As causes a reduction in root elongation by inducing an oxidative stress that is related to enhanced lipid peroxidation, but not to H2O2 accumulation.
285 citations
TL;DR: CP-Pt may be a SOD/catalase mimetic which is useful for medical treatment of oxidative stress diseases and quenched hydrogen peroxide and superoxide anion radical in dose-dependent manners.
Abstract: Bimetallic nanoparticles consisting of gold and platinum were prepared by a citrate reduction method and complementarily stabilized with pectin (CP-Au/Pt). The percent mole ratio of platinum was varied from 0 to 100%. The CP-Au/Pt were alloy-structured. They were well dispersed in water. The average diameter of platinum nanoparticles (CP-Pt) was 4.7 ± 1.5 nm. Hydrogen peroxide (H2O2) was quenched by CP-Au/Pt consisting of more than 50% platinum whereas superoxide anion radical () was quenched by any CP-Au/Pt. The CP-Au/Pt quenched these two reactive oxygen species in dose-dependent manners. The CP-Pt is the strongest quencher. The CP-Pt decomposed H2O2 and consequently generated O2 like catalase. The CP-Pt actually quenched which was verified by a superoxide dismutase (SOD) assay kit. This quenching activity against persisted like SOD. Taken together, CP-Pt may be a SOD/catalase mimetic which is useful for medical treatment of oxidative stress diseases.
261 citations
TL;DR: The effects of quercetin on A549 cells in in vitro culture were found to be complex and include both antioxidant effects and induction of oxidative stress due to formation of reactive oxygen species in the extracellular medium.
TL;DR: High B concentration in the culture medium provokes oxidative damage in tomato leaves and induces a general increase in antioxidant enzyme activity, which increases ascorbate pool size.
TL;DR: A limitation in metabolic capacity of bacteroids and oxidative damage of cellular components are contributing factors to the inhibition of N2ase activity in alfalfa nodules, and it is concluded that oxidative stress occurs in nodules under drought conditions prior to any detectable effect on SS or leghemoglobin.
Abstract: Alfalfa (Medicago sativa) plants were exposed to drought to examine the involvement of carbon metabolism and oxidative stress in the decline of nitrogenase (N2ase) activity. Exposure of plants to a moderate drought (leaf water potential of −1.3 MPa) had no effect on sucrose (Suc) synthase (SS) activity, but caused inhibition of N2ase activity (−43%), accumulation of succinate (+36%) and Suc (+58%), and up-regulation of genes encoding cytosolic CuZn-superoxide dismutase (SOD), plastid FeSOD, cytosolic glutathione reductase, and bacterial MnSOD and catalases B and C. Intensification of stress (−2.1 MPa) decreased N2ase (−82%) and SS (−30%) activities and increased malate (+40%), succinate (+68%), and Suc (+435%). There was also up-regulation (mRNA) of cytosolic ascorbate peroxidase and down-regulation (mRNA) of SS, homoglutathione synthetase, and bacterial catalase A. Drought stress did not affect nifH mRNA level or leghemoglobin expression, but decreased MoFe- and Fe-proteins. Rewatering of plants led to a partial recovery of the activity (75%) and proteins (>64%) of N2ase, a complete recovery of Suc, and a decrease of malate (−48%) relative to control. The increase in O2 diffusion resistance, the decrease in N2ase-linked respiration and N2ase proteins, the accumulation of respiratory substrates and oxidized lipids and proteins, and the up-regulation of antioxidant genes reveal that bacteroids have their respiratory activity impaired and that oxidative stress occurs in nodules under drought conditions prior to any detectable effect on SS or leghemoglobin. We conclude that a limitation in metabolic capacity of bacteroids and oxidative damage of cellular components are contributing factors to the inhibition of N2ase activity in alfalfa nodules.
TL;DR: Dietary supplementation with resveratrol during ethanol treatment inhibited hepatic lipid peroxidation and ameliorated SOD, GPx and CAT activities in the liver, and caused drastic alterations in antioxidant defence systems.
TL;DR: Investigation of roots of rice grown hydroponically with Cd showed that pretreatment with SA enhanced the antioxidant defense activities in Cd-stressed rice, thus alleviatingCd-induced oxidative damage and enhancing Cd tolerance.
TL;DR: The results suggest that temperature variation does alter the active oxygen metabolism by modulating antioxidant enzyme activities, which can be used as biomarker to detect sublethal effects of pollution.
TL;DR: Findings suggest that resveratrol is able to cross the blood brain barrier and exerts potent antioxidant features and also exerts neuroprotective properties by up regulating several detoxifying enzymes, most of which are iron proteins.
Abstract: We have studied the effect of resveratrol on lipoperoxidation and antioxidant enzyme activity level in the brain of healthy rats. When intraperitoneally administered, resveratrol significantly and dose dependently decreased brain malondialdehyde level. Resveratrol also increased in a dose-dependent way brain superoxide dismutase, catalase and peroxidase activities. Optimal effect on antioxidant enzyme and lipoperoxidation products were obtained with resveratrol concentration of 12.5 mg/kg body wt. Native polyacrylamide gel electrophoresis analysis of antioxidant isoenzymes revealed that resveratrol up regulated at least two acidic superoxide dismutase isoforms called A(1) and A(2), two basic isoforms called B(1) and B(2). Resveratrol also up regulated two catalase isoforms and a broad peroxidase band corresponding to several isoforms. All these findings suggest that resveratrol is able to cross the blood brain barrier and exerts potent antioxidant features. Resveratrol also exerts neuroprotective properties by up regulating several detoxifying enzymes, most of which are iron proteins.
TL;DR: The constitutive presence of catalase inside mitochondria is demonstrated by several methodological approaches as follows: biochemical fractionating, proteinase K sensitivity, and immunogold electron microscopy on isolated RLM and whole rat liver tissue.
TL;DR: The results suggest that catalase had the most pronounced effect in improving post-thaw quality of canine spermatozoa and none of the reactive oxygen species were significantly reduced post-Thaw in antioxidant treated semen.
TL;DR: In this article, the effect of silicon (Si) on the growth, uptake of sodium (Na), chloride (Cl), boron (B), stomatal resistance (SR), lipid peroxidation (MDA), membrane permeability (MP), lipoxygenase (LOX) activity, proline (PRO) accumulation, H2O2 accumulation, nonenzymatic antioxidant activity (AA) and the activities of major antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT and ascorbate peroxidase, AP
Abstract: We investigated effect of silicon (Si) on the growth, uptake of sodium (Na), chloride (Cl), boron (B), stomatal resistance (SR), lipid peroxidation (MDA), membrane permeability (MP), lipoxygenase (LOX) activity, proline (PRO) accumulation, H2O2 accumulation, non-enzymatic antioxidant activity (AA) and the activities of major antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT and ascorbate peroxidase, APX) of spinach and tomato grown in sodic-B toxic soil. Si applied to the sodic-B toxic soil at 2.5 and 5.0 mM concentrations significantly increased the Si concentration in the plant species and counteracted the deleterious effects of high concentrations of Na, Cl and B on root and shoot growth by lowering the accumulation of these elements in the plants. Stomatal resistance, MP, MDA and the concentrations of H2O2 and PRO were higher in the plants grown in sodic-B toxic soil without Si: LOX activity of excised leaves of both species was increased by Si. Antioxidant activities of both species were significantly affected by Si, with the activities of SOD, CAT and APX decreased and AA increased by applied Si. For most of the parameters measured, it was found that 5 mM Si was more effective than the 2.5 mM Si. Based on the present work, it can be concluded that Si alleviates sodicity and B toxicity of the plants grown in sodic-B toxic soil by preventing both oxidative membrane damage and also translocation of Na, Cl and B from root to shoots and/or soil to plant, and lowering the phytotoxic effects of Na, Cl and B within plant tissues. It was concluded that tomato was more responsive to Si than spinach since it was more salt sensitive than spinach. To our knowledge, this is the first report that Si improves the combined salt and B tolerance of spinach and tomato grown in naturally sodic-B toxic soil, and which describes membrane-related parameters and antioxidant responses.
TL;DR: In this article, oxalic acid (OA) or salicylic acid (SA) aqueous solutions, mango (Mangifera indica L. cv. Zill) fruit were stored at 14°C or at 5°C with shelf life to determine the effects of exogenous OA or SA on reactive oxygen metabolism, quality and chilling injury.
Abstract: After being immersed in water, oxalic acid (OA) or salicylic acid (SA) aqueous solutions, mango (Mangifera indica L. cv. Zill) fruit were stored at 14°C or at 5°C with shelf life to determine the effects of exogenous OA or SA on reactive oxygen metabolism, quality and chilling injury (CI) of the fruit. Mango CI could be reduced by OA and SA treatments. Compared with that in control, accompanied with alleviated CI at shelf life, fruit treated with OA or SA had significantly higher reduction states of ascorbate and glutathione. Moreover, the treated fruit showed lower superoxide anion content, higher hydrogen peroxide content, lower lipoxygenase (EC 1.13.11.12) activity and higher activities of superoxide dismutase (EC 1.15.1.1), catalase (EC 1.11.1.6), guaiacol peroxidase (EC 1.11.1.7), ascorbate peroxidase (EC 1.11.1.11) and glutathione reductase (EC 1.6.4.2). In addition, fruit firmness, total soluble solids and titratable acidity content were not obviously affected by OA and SA treatments. It was suggested that the effect of OA or SA on mango CI probably attributed to more reducing status of ascorbate and glutathione, less O2− accumulation and more H2O2 accumulation.
TL;DR: It is concluded that cell-mediated delivery of nanozymes can reduce oxidative stress in laboratory and animal models of PD.
TL;DR: It is reported here that ABA-, drought-, and salt stress-induced gene expression of CAT1 catalase is mediated by AtMEK1, an Arabidopsis MAPK kinase, by triggering H(2)O( 2) signal production.
Abstract: Catalase and hydrogen peroxide (H2O2) have been extensively studied for their roles in various stress responses. However, little is known about the triggering mechanisms for stress-induced catalase gene expression or about H2O2 production as a stress signal. It is reported here that ABA-, drought-, and salt stress-induced gene expression of CAT1 catalase is mediated by AtMEK1, an Arabidopsis MAPK kinase, by triggering H2O2 signal production. Both CAT1 expression and AtMEK1 activity were activated by ABA, drought, and salt stresses. The mek1 mutant totally blocked stress-induced CAT1 expression and, interestingly, stress-induced H2O2 production was also blocked. Over-expression of AtMEK1 significantly promoted stress-induced CAT1 expression, and also promoted H2O2 production. These results conclusively indicate that stress-induced CAT1 expression is mediated by AtMEK1 and, furthermore, that the triggering of H2O2 production might be involved in this process, as further proved by the observation that CAT1 expression was induced by applied H2O2. Surprisingly, the signalling mechanisms for stress-induced gene expression of CAT2 and CAT3 were very different from that of CAT1. Except for drought stress, expression of CAT2 or CAT3 was also activated by salt stress or ABA treatment, and AtMEK1 was not proved to be involved in the drought-induced expression of CAT2 or CAT3. Further studies showed that stomatal movement was much less sensitive to ABA in AtMEK1 mutant (mek1), and over-expression of AtMEK1 in Arabidopsis increased plant resistance to drought or salt stress, which further demonstrated that AtMEK1 is a crucial mediator in plant stress signal transduction.
TL;DR: The results showed that the overproduction of OsAPXb enhanced and maintained APX activity to a much higher degree thanOsAPXa in transgenic Arabidopsis during treatment with different concentrations of NaCl, enhanced the active oxygen scavenging system, and protected plants from salt stress by equilibrating H2O2 metabolism.
Abstract: In order to determine the different roles of rice (Oryza sativa L.) cytosolic ascorbate peroxidases (OsAPXa and OsAPXb, GenBank accession nos. D45423 and AB053297, respectively) under salt stress, transgenic Arabidopsis plants over-expressing OsAPXa or OsAPXb were generated, and they all exhibited increased tolerance to salt stress compared to wild-type plants. Moreover, transgenic lines over-expressing OsAPXb showed higher salt tolerance than OsAPXa transgenic lines as indicated by root length and total chlorophyll content. In addition to ascorbate peroxidase (APX) activity, antioxidant enzyme activities of catalase (CAT), superoxide dismutase (SOD) and glutathione reductase (GR), which are also involved in the salt tolerance process, and the content of H2O2 were also assayed in both transgenic and wild-type plants. The results showed that the overproduction of OsAPXb enhanced and maintained APX activity to a much higher degree than OsAPXa in transgenic Arabidopsis during treatment with different concentrations of NaCl, enhanced the active oxygen scavenging system, and protected plants from salt stress by equilibrating H2O2 metabolism. Our findings suggest that the rice cytosolic OsAPXb gene has a more functional role than OsAPXa in the improvement of salt tolerance in transgenic plants.
TL;DR: The overexpression of catalase attenuated ROS generation, angiotensinogen and proapoptotic gene expression and apoptosis in the kidneys of diabetic mice in vivo point to an important role of ROS in the pathophysiology of diabetic nephropathy.
TL;DR: The present results indicate that the oxidant parameters increased and antioxidant parameters decreased in patients with osteoarthritis; therefore, these patients may be exposed to a potent oxidative stress.
Abstract: The purpose of this study was to determine serum oxidative/antioxidative status in patients with knee osteoarthritis and its relation with prolidase activity, which plays an important role in collagen metabolism. Serum antioxidative status was evaluated by measuring total antioxidant capacity (TAC), thiol level and catalase enzyme activity in patients with osteoarthritis and in healthy controls. Serum oxidative status was evaluated by measuring total peroxide (TP) and lipid hydroperoxide. Oxidative stress index (OSI) was calculated. Prolidase enzyme activity was measured to investigate the collagen metabolism. Serum TAC, thiol level, catalase activity and prolidase activity were significantly lower in patients than in controls (P < 0.001, for all). In contrast, TP, lipid hydroperoxide and OSI values were significantly higher in patients than in controls (P < 0.001 for all). Further, prolidase activity was negatively correlated with TP and OSI, and positively correlated with TAC. The present results indicate that the oxidant parameters increased and antioxidant parameters decreased in patients with osteoarthritis; therefore, these patients may be exposed to a potent oxidative stress. Decreased collagen metabolism may be related with oxidative stress, which has a role in the ethiopathogenesis and/or in the progression of the disease.
TL;DR: The results indicated that priming is an important cellular mechanism in SAR by thiamine and requires hydrogen peroxide and intact NPR1.
Abstract: Thiamine confers systemic acquired resistance (SAR) on susceptible plants through priming, leading to rapid counterattack against pathogen invasion and perturbation of disease progress. Priming reduces the metabolic cost required for constitutive expression of acquired resistance. To investigate the effects of priming by thiamine on defense-related responses, Arabidopsis (Arabidopsis thaliana) was treated with thiamine and effects of pathogen challenge on the production of active oxygen species, callose deposition, hypersensitive cell death, and pathogenesis-related 1 (PR1)/Phe ammonia-lyase 1 (PAL1) gene expression was analyzed. Thiamine did not induce cellular and molecular defense responses except for transient expression of PR1 per se; however, subsequent Pseudomonas syringae pv tomato challenge triggered pronounced cellular defense responses and advanced activation of PR1/PAL1 gene transcription. Thiamine treatment and subsequent pathogen invasion triggered hydrogen peroxide accumulation, callose induction, and PR1/PAL1 transcription activation in Arabidopsis mutants insensitive to jasmonic acid (jar1), ethylene (etr1), or abscisic acid (abi3-3), but not in plants expressing bacterial NahG and lacking regulation of SAR (npr1 [nonexpressor of PR genes 1]). Moreover, removal of hydrogen peroxide by catalase almost completely nullified cellular and molecular defense responses as well as SAR abolishing bacterial propagation within plants. Our results indicated that priming is an important cellular mechanism in SAR by thiamine and requires hydrogen peroxide and intact NPR1.
TL;DR: The results suggest that BAP protects the cell membranes and the photosynthetic machinery from oxidative damage during delay of senescence in the dark, and reduces levels of reactive oxygen species (ROS), and enhances the activity of antioxidant enzymes (CAT, APX).
TL;DR: In this article, the authors investigated the effect of temperature on enzyme activity in grassland soils from a European temperate-humid zone (Galicia, NW Spain) and found that the soil containing the least amount of organic matter (OM) showed the lowest enzyme activity for all temperatures and enzymes.
Abstract: The thermodynamic parameters of the enzymes catalase, dehydrogenase, casein-protease, α -N-benzoyl- l -argininamide (BAA)-protease, urease, Carboxymethyl (CM)-cellulase, invertase, β -glucosidase and arylsulphatase, were investigated in grassland soils from a European temperate-humid zone (Galicia, NW Spain). The effect of temperature on enzyme activity was determined at 5, 18, 27, 37, 57 and 70 °C. The temperature-dependence of the rate of substrate hydrolysis varied depending on the enzyme and soil. In general, the soil containing the least amount of organic matter (OM) showed the lowest enzyme activity for all temperatures and enzymes, whereas soils with similar OM contents showed similar levels of activity for the entire temperature range. Temperature had a noteworthy effect on the activity of oxidoreductases. Product formation in the reaction catalyzed by dehydrogenase increased with increasing temperature until 70 °C, which was attributed to chemical reduction of iodonitrotetrazolium violet (INT) at high temperatures. Catalase activity was not affected above 37 °C, which may be explained either by non-enzymatic decomposition of hydrogen peroxide or by the fact that catalase has reached kinetic perfection, and is therefore not saturated with substrate. The Arrhenius equation was used to determine the activation energy ( E a ) and the temperature coefficient ( Q 10 ) for all enzymes. The values of E a and Q 10 for each enzyme differed among soils, although in general the differences were small, especially for those enzymes that act on substrates of low molecular weight. In terms of the values of E a and Q 10 and the differences established among soils, the results obtained for those enzymes that act on substrates of high molecular weight differed most from those corresponding to the other enzymes. Thus the lowest E a and Q 10 values corresponded to BAA-protease, and the highest values to CM-cellulase and casein-protease. Except for catalase in one of the soils, the values of E a and Q 10 for the oxidoreductases were similar to those of most of the hydrolases. In general, the effect of temperature appeared to be more dependent on the type of enzyme than on the characteristics of the soil.
TL;DR: In this article, the role of reactive oxygen species (ROS), such as superoxide anion and hydrogen peroxide (H2O2), generated from 6-hydroxydopamine (6-OHDA) is investigated.