Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P04040 (Catalase)
 3,577 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Oxidative stress responses were tested in the unicellular cyanobacterium synechococcus PCC 7942 (R-2). Cells were exposed to hydrogen peroxide, cumene hydroperoxide and high light intensities. The extent and time course of oxidative stress were related to the activities of ascorbate peroxidase and catalase. Ascorbate peroxidase was found to be the major enzyme involved in the removal of hydrogen peroxide under the tested oxidative stress. Catalase activity was inhibited in cells, treated with high H2O2 concentrations, and was not induced under photooxidative stress. Catalase was specifically induced in cells treated with cumene hydroperoxide. Superoxide dismutase activity increased under conditions generating superoxide, such as high light intensities. The induction of the antioxidative enzymes was light dependent and was inhibited by chloramphenicol.
 ...
PMID:Oxidative stress responses in the unicellular cyanobacterium Synechococcus PCC 7942. 190 71

The enzymes involved in antioxidative activity and the cellular content of the antioxidants glutathione and ascorbate in the cyanobacteria Nostoc muscorum 7119 and Synechococcus 6311 have been examined for their roles in hydroperoxide removal. High activities of ascorbate peroxidase and catalase were found in vegetative cells of both species and in the heterocysts of N. muscorum. The affinity of ascorbate peroxidase for H2O2 was 15- to 25-fold higher than that of catalase. Increased activity of ascorbate peroxidase was observed in N. muscorum when H2O2 production was enhanced by photorespiration. Catalase activity was decreased in dilute cultures whereas ascorbate peroxidase activity increased. Ascorbate peroxidase activity also increased when the CO2 concentration was reduced. Ascorbate peroxidase appears to be a key enzyme in a cascade of reactions regenerating antioxidants. Dehydroascorbate reductase was found to regenerate ascorbate, and glutathione reductase recycled glutathione. In vegetative cells glutathione was present in high amounts (2-4 mM) whereas the ascorbate content was almost 100-fold lower (20-100 microM). Glutathione peroxidase was not detected in either cyanobacterium. It is concluded from the high activity of ascorbate peroxidase activity and the levels of antioxidants found that this enzyme can effectively remove low concentrations of peroxides. Catalase may remove H2O2 produced under photooxidative conditions where the peroxide concentration is higher.
 ...
PMID:Hydroperoxide metabolism in cyanobacteria. 308 78

Four putative heat-tolerant tomato (Lycopersicum esculentum) cultivars (Tamasabro, Heat Wave, LHT-24, and Solar Set) and one putative heat-sensitive tomato cultivar (Floradade) were grown in the field under non-stress (average daily temperature of 26 degrees C) and heat-stress (average daily temperature of 34 degrees C) conditions. At anthesis, approximately five weeks after being transplanted to the field, leaf samples were collected for antioxidant analyses. Yield was determined by harvesting ripe fruit seven weeks after the collection of leaf samples. Heat stress resulted in a 79.1% decrease in yield for the heat-sensitive Floradade, while the fruit yield in the heat-tolerant cultivars Heat Wave, LHT-24, Solar Set, and Tamasabro was reduced 51.5%, 22.1%, 43.8%, and 34.8% respectively. When grown under heat stress, antioxidant activities were also greater in the heat-tolerant cultivars. Superoxide dismutase (SOD) activity increased up to 9-fold in the heat-tolerant cultivars but decreased 83.1% in the heat-sensitive Floradade. Catalase, peroxidase, and ascorbate peroxidase activity increased significantly in all cultivars. Only Heat Wave showed a significant increase in glutathione reductase in response to heat stress but all heat-tolerant cultivars exhibited significantly lower oxidized ascorbate/reduced ascorbate ratios, greater reduced glutathione/oxidized glutathione rations, and greater alpha-tocopherol concentrations compared to the heat-sensitive cultivar Floridade. These data indicate that the more heat-tolerant cultivars had an enhanced capacity for scavenging active oxygen species and a more active ascorbate-glutathione cycle and suggest a strong correlation between the ability to up-regulate the antioxidant defense system and the ability of tomatoes to produce greater yields when grown under heat stress.
 ...
PMID:The relationship between yield and the antioxidant defense system in tomatoes grown under heat stress. 890 41

Hydrogen peroxide (H2O2) has been implicated in many stress conditions. Control of H2O2 levels is complex and dissection of mechanisms generating and relieving H2O2 stress is difficult, particularly in intact plants. We have used transgenic tobacco with approximately 10% wild-type catalase activity to study the role of catalase and effects of H2O2 stress in plants. Catalase-deficient plants showed no visible disorders at low light, but in elevated light rapidly developed white necrotic lesions on the leaves. Lesion formation required photorespiratory activity since damage was prevented under elevated CO2. Accumulation of H2O2 was not detected during leaf necrosis. Alternative H2O2-scavenging mechanisms may have compensated for reduced catalase activity, as shown by increased ascorbate peroxidase and glutathione peroxidase levels. Leaf necrosis correlated with accumulation of oxidized glutathione and a 4-fold decrease in ascorbate, indicating that catalase is critical for maintaining the redox balance during oxidative stress. Such control may not be limited to peroxisomal H2O2 production. Catalase functions as a cellular sink for H2O2, as evidenced by complementation of catalase deficiency by exogenous catalase, and comparison of catalase-deficient and control leaf discs in removing external H2O2. Stress analysis revealed increased susceptibility of catalase-deficient plants to paraquat, salt and ozone, but not to chilling.
 ...
PMID:Catalase is a sink for H2O2 and is indispensable for stress defence in C3 plants. 930 23

We compared the antioxidant enzyme activities between Solanum tuberosum L. cultivars Kitaakari and "Danshaku" during storage at 1 degrees C and 20 degrees C. The Kitaakari and Danshaku plants contained approximately 330 microM and 120 microM ascorbic acid (AsA) immediately after the harvest, respectively. At 1 degrees C, the activity of ascorbate peroxidase (APx) in the Kitaakari plants showed the tendency to increase, while in the Danshaku its activity increased temporally by 9 weeks and thereafter returned to basal levels. Superoxide dismutase (SOD) activity increased after 12 weeks in the case of the Kitaakari at 1 degrees C. Catalase did not show any difference in both cultivars at each temperature. The contents of AsA, which was one of the substrates of APx, decreased more rapidly at 1 degrees C than at 20 degrees C in both cultivars. Particularly in the case of the Danshaku, AsA contents were already less than 30 microM at 9 weeks, which confirmed that APx was inactivated.
 ...
PMID:Comparison of antioxidant enzyme activities between Solanum tuberosum L. Cultivars Danshaku and Kitaakari during low-temperature storage. 1088 8

The distribution of antioxidants between bundle sheath and mesophyll cells of maize leaves was analysed in plants grown at 20 degrees C, 18 degrees C and 15 degrees C. The purity of the isolated bundle sheath and mesophyll fractions was determined using compartment-specific marker enzymes. In plants grown at 15 degrees C, ascorbate peroxidase, CuZn-superoxide dismutase (CuZn-SOD) and monodehydroascorbate reductase activities were increased in the bundle sheath cells, and glutathione reductase, dehydroascorbate reductase and monodehydroascorbate reductase activities were enhanced in the mesophyll cells. SOD was absent from the mesophyll of plants grown at 20 degrees C but an Fe-SOD activity was found in the mesophyll of plants grown at 15 degrees C. Foliar Mn-SOD activities were decreased at 15 degrees C compared to 20 degrees C. Catalase was undetectable in the mesophyll extracts of plants grown at 15 degrees C. Ascorbate and glutathione contents were considerably higher in the mesophyll than the bundle sheath fractions of plants grown at 20 degrees C. The ratios of reduced to oxidized forms of these antioxidants were significantly decreased in the bundle sheath, but increased in the mesophyll of leaves grown at 15 degrees C. Foliar H2O2 accumulated at 15 degrees C compared to 20 degrees C. Most of the foliar H2O2 was localized in the mesophyll tissues at all growth temperatures. The differential distribution of antioxidants between leaf bundle sheath and mesophyll tissues, observed at 20 degrees C, is even more pronounced when plants are grown at 15 degrees C and may contribute to the extreme sensitivity of maize to low temperatures.
 ...
PMID:Low temperature-induced changes in the distribution of H2O2 and antioxidants between the bundle sheath and mesophyll cells of maize leaves. 1093 1

Cucumber seedling radicles become more chilling sensitive as they elongate. Chilling seedlings with radicles 20 mm long for 48 h at 2.5 degrees C inhibited subsequent growth by 36%, while it reduced the growth of 70 mm-long radicles by 63%. Although the growth rate of non-chilled cucumber radicles at 25 degrees C is constant from 20 to 80 mm, tissue viability [i.e. reduction of TTC (2,3,5-triphenyltetrazolium chloride) to formazan] and DPPH (alpha,alpha-diphenyl-beta-picrylhydrazyl) radical scavenging activity of apical tissue declines as radicles elongate from 20 to 80 mm in length. TTC reduction, DPPH-radical scavenging activity and protein content of apical tissue were higher in 20 than in 70 mm radicles immediately after chilling and after an additional 48 h of growth at 25 degrees C. Catalase (CAT; EC 1.11.1.6) and ascorbate peroxidase (APX; EC 1.11.1.11) activity was higher in the apical tissue of 20 than in 70 mm radicles before chilling. Immediately after chilling and after an additional 48 h at 25 degrees C, superoxide dismutase (SOD; EC 1.15.1.1), glutathione reductase (GR; EC 1.6.4.2), and guaiacol peroxidase (GPX; EC 1.11.1.7) activity increased more rapidly in 70 mm radicles than in 20 mm radicles (SOD, GR, and GPX activity in 70 mm radicles was 1.5-, 1.9- and 8.6-fold higher, respectively, than in 20 mm radicles). However, APX and CAT activity in 20 mm radicles were always higher than in 70 mm radicles. Growth after chilling enhanced the activity of all antioxidant enzymes compared to that found in non-chilled tissue; however, CAT activity in 70 mm radicles did not recover to levels found in non-chilled tissue. Higher levels of CAT, APX and DPPH-radical scavenging activity are correlated with higher chilling tolerance of 20 mm-long cucumber radicles compared to 70 mm-long radicles.
 ...
PMID:Reduced chilling tolerance in elongating cucumber seedling radicles is related to their reduced antioxidant enzyme and DPPH-radical scavenging activity. 1206 Feb 42

Catalase-peroxidases (KatGs) are heme peroxidases with homology to yeast cytochrome cperoxidase (CCP) and plant ascorbate peroxidases (APXs). KatGs exhibit a peroxidase activity of broad specificity and a high catalase activity, which strongly depends on the presence of a distal Trp as part of the conserved amino acid triad Arg-Trp-His. By contrast, both CCP and APX do not have a substantial catalase activity despite the presence of the same triad. Thus, to elucidate structure-function relationships of catalase-peroxidases (for which no crystal structure is available at the moment), we performed UV-Vis and resonance Raman studies of recombinant wild-type KatG from the cyanobacterium SynechocystisPCC 6803 and the distal side variants (His123-->Gln, Glu; Arg119-->Ala, Asn; Trp122-->Phe, Ala). The distal cavity of KatG is very similar to that of the other class I peroxidases. A H-bond network involving water molecules and the distal Trp, Arg, and His is present, which connects the distal and proximal sides of the heme pocket. However, distal mutation not only affects the heme Fe coordination state and perturbs the proximal Fe-Im bond, as previously observed for other peroxidases, but also alters the stability of the heme architecture. The charge of the distal residues appears particularly important for maintaining the heme architecture. Moreover, the Trp plays a significant role in the distal H-bonding, much more pronounced than in CCP. The relevance of these findings for the catalase activity of KatG is discussed in light of the complete loss of catalase activity in the distal Trp mutants.
 ...
PMID:New insights into the heme cavity structure of catalase-peroxidase: a spectroscopic approach to the recombinant synechocystis enzyme and selected distal cavity mutants. 1211 39

Catalase-peroxidases (KatGs) are prokaryotic heme peroxidases with homology to yeast cytochrome c peroxidase (CCP) and plant ascorbate peroxidases (APXs). KatGs, CCP and APXs contain identical amino acid triads in the heme pocket (distal Arg/Trp/His and proximal His/Trp/Asp), but differ dramatically in their reactivities towards hydrogen peroxide and various one-electron donors. Only KatGs have high catalase activity in addition to a peroxidase activity of broad specificity. Here, we investigated the effect of mutating the conserved proximal triad on KatG catalysis. With the exception of W341F, all variants (H290Q, W341A, D402N, D402E) exhibited a catalase activity <1% of wild-type KatG and spectral properties indicating alterations in heme coordination and spin states. Generally, the peroxidase activity was much less effected by these mutations. Compared with wild-type KatG the W341F variant had a catalase and halogenation activity of about 40% and an even increased overall peroxidase activity. This variant, for the first time, allowed to monitor the hydrogen peroxide mediated transitions of ferric KatG to compound I and back to the resting enzyme. Compound I reduction by aromatic one-electron donors (o-dianisidine, pyrogallol, aniline) was not influenced by exchanging Trp by Phe. The findings are discussed in comparison with the data known from CCP and APX and a reaction mechanism for the multifunctional activity of the W341F variant is suggested.
 ...
PMID:Engineering the proximal heme cavity of catalase-peroxidase. 1212 64

The aim of this work was to determine the compartmentation of antioxidants between the bundle-sheath and mesophyll cells of maize (Zea mays L.) leaves. Rapid fractionation of the mesophyll compartment was used to minimize modifications in the antioxidant status and composition due to extraction procedures. The purity of the mesophyll isolates was assessed via the distribution of enzyme and metabolite markers. Ribulose-1,5 bisphosphate and ribulose-1,5-bisphosphate carboxylase/oxygenase were used as bundle-sheath markers and phosphoenolpyruvate carboxylase was used as the mesophyll marker enzyme. Glutathione reductase and dehydroascorbate reductase were almost exclusively localized in the mesophyll tissue, whereas ascorbate, ascorbate peroxidase, and superoxide dismutase were largely absent from the mesophyll fraction. Catalase, reduced glutathione, and monodehydroascorbate reductase were found to be approximately equally distributed between the two cell types. It is interesting that, whereas H2O2 levels were relatively high in maize leaves, this oxidant was largely restricted to the mesophyll compartment. We conclude that the antioxidants in maize leaves are partitioned between the two cell types according to the availability of reducing power and NADPH and that oxidized glutathione and dehydroascorbate produced in the bundle-sheat tissues have to be transported to the mesophyll for re-reduction to their reduced forms.
 ...
PMID:Differential Localization of Antioxidants in Maize Leaves. 1222 57


1 2 3 4 5 6 Next >>