Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.6.5.4 (SOR)
720 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The utility of antioxidant enzymes, viz glutathione-S-transferase (GST), glutathione reductase (GR), superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione peroxidase (GPX), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR), as biomarkers of heavy metal pollution in water was investigated using the Allium cepa (onion) system. These antioxidant enzymes were assayed in onion bulbs exposed to certain heavy metals taken separately, the test metals taken in combination as well as the industrial wastewater especially found to contain these metals. GST exhibited significantly enhanced activity upon treatment with individual heavy metals. However, GR, SOD and CAT did not show such a pronounced increase in activities. At higher heavy metal concentrations, GR, SOD and CAT showed a steep decline while GST activity still showed a rise. Moreover, APX, GPX and MDHAR also exhibited remarkable induction with increase in the concentration of individual heavy metals. However, there was no significant change in DHAR activity with respect to the controls. Metabolites like ascorbate (ASC) and glutathione (GSH) exhibited significant decline with increase in the concentration of individual heavy metals while the level of H(2)O(2) continued to display the rise up to a heavy metal concentration of 100 microM, after which it showed a gradual decline. A. cepa bulbs treated with wastewater sample showed enzyme activity profiles similar to that shown with heavy metals, thereby suggesting the presence of heavy metals in the test wastewater. Atomic absorption spectrophotometry also detected large amounts of Cd, Cr, Cu, Hg, Pb and Zn in the test water sample. The metal mixture, containing the amounts of heavy metals equivalent to those found in the wastewater, resulted in steep declines in GR, SOD and CAT activities in A. cepa while GST showed a rise. However, when this metal mixture was diluted to 2000-fold, GR, SOD and CAT also showed enhanced activities compared with the controls. Contrary to the above finding, APX, GPX and MDHAR exhibited the rise in activities in A. cepa exposed to the metal mixture at all dilutions. In the presence of cycloheximide, all the enzymes returned to the levels of untreated controls while chloramphenicol did not have any effect on the test enzymes, thereby suggesting de novo protein synthesis of the test antioxidant enzymes in the cytosolic compartment of the cell as a result of exposure to the heavy metals.
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PMID:Certain antioxidant enzymes of Allium cepa as biomarkers for the detection of toxic heavy metals in wastewater. 1599 99

Roots of Panax ginseng exposed to various concentrations of Cu (0.0, 5, 10.0, 25.0, and 50.0 microM) accumulated high amounts of Cu in a concentration-dependent and duration-dependent manner. Roots treated with 50 microM Cu resulted in 52% and 89% growth inhibition after 20 and 40 days, respectively. Saponin synthesis was stimulated at a Cu concentration between 5 and 25 muM but decreased at 50 microM Cu. Malondialdehyde content (MDA), lipoxygenase activity (LOX), superoxide ion (O2*-) accumulation, and H2O2 content at 5 and 10 microM Cu-treated roots were not increased but strongly increased at 50 microM Cu resulting in the oxidation of ascorbate (ASC) and glutathione (GSH) to dehydroascorbate (DHA) and glutathione disulfide (GSSG), respectively indicating a clear oxidative stress. Seven well-resolved bands of superoxide dismutase (SOD) were detected in the gel and an increase in SOD activity seemed to be mainly due to the induction of Fe-SOD 3. Five to 10 microM Cu slightly induced activity of ascorbate peroxidase (APX) and dehydroascorbate reductase (DHAR), guaiacol peroxidase (G-POD) but inhibited monodehydroascorbate reductase (MDHAR) and glutathione reductase (GR) enzyme activities. No changes in catalase (CAT) activity and in activity gel were found up to 25 microM Cu, but both G-POD and CAT activities were inhibited at 50 microM Cu. Glutathione metabolism enzymes such as gamma-glutamylcysteine synthetase (gamma-GCS), glutathione-S-transferase (GST), and glutathione peroxidase activities (GPx) were activated at 5 and 10 microM Cu but were strongly inhibited at 50 microM Cu due to the Cu accumulation in root tissues. The strong depletion of GSH at 50 microM Cu was associated to the strong induction of gamma-glutamyltranspeptidase (gamma-GGT) activity. These results indicate that plant could grow under Cu stress (5-25 microM) by modulating the antioxidant defense mechanism for combating Cu induced oxidative stress.
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PMID:Copper-induced changes in the growth, oxidative metabolism, and saponin production in suspension culture roots of Panax ginseng in bioreactors. 1680 51

The behaviour of the Ginkgo biloba L. seeds was studied during storage at 4 and 25 degrees C. When stored at 25 degrees C, all the seeds died in 6 months. Cold temperatures preserved seed tissue viability for 1 year but did not preserve their capability to germinate, since such capability decreased after 6 months. A significant increase in lipid peroxidation occurred in the seed both in the embryo and in the endosperm. During storage a progressive deterioration of the endosperm tissues was evident. The two major water soluble antioxidants, ascorbate (ASC) and glutathione (GSH), showed different behaviour in the two conditions of storage and in the two main structures of the seed, the embryo and the endosperm. The ASC content of embryos and endosperms remained quite unchanged in the first 9 months at 4 degrees C, then increased. At 25 degrees C a significant decrease in the ASC content in the embryos was evident, whereas it remained more stable in the endosperm. The GSH pool decreased at both storage temperatures in the embryos. As far as the ASC-GSH redox enzymes are concerned, their activities decreased with storage, but changes appeared to be time-dependent more than temperature-dependent, with the exception of the endosperm ascorbate free radical (AFR) reductase (EC 1.6.5.4), the activity of which rapidly decreased at 25 degrees C. Therefore overall the antioxidant enzymes were scarcely regulated and unable to counteract oxidative stress occurring during the long-term storage.
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PMID:Effects of storage temperature on viability, germination and antioxidant metabolism in Ginkgo biloba L. seeds. 1688 78

The long-term effects of 50 microM CdCl(2) on the enzymatic and non-enzymatic antioxidative defences of pea (Pisum sativum L.) plants was studied in terms of activity, protein content and transcripts levels. Cadmium caused a reduction of the total glutathione content (GSH+GSSG), with the reduced form of glutathione (GSH) being most affected. The content of ascorbic acid (ASC) was also decreased by the treatment. The transcript levels of catalase (CAT) and monodehydroascorbate reductase (MDHAR) showed a Cd-dependent increase, although CAT activity and its protein content were depressed, which suggests a posttranslational modification of this protein induced by cadmium. Glutathione reductase (GR), and ascorbate peroxidase (APX) did not change significantly, either in activity or accumulation of transcript. However, cadmium treatment provoked a strong reduction in mRNA, protein level and activity of CuZn-superoxide dismutase (SOD), being the most negatively affected antioxidative enzyme, and in less extent of Mn-SOD. Transcriptome analysis of the antioxidative enzymes in leaves of pea plants grown with cadmium and treated with some modulators of the signal transduction cascade suggested that at least Ca(2+) channels, phosphorylation/dephosphorylation processes, nitric oxide, cGMP, salicylic acid (SA) and H(2)O(2) were involved in some steps between the cadmium signal and transcript expression of CuZn-SOD, CAT and MDHAR. This indicated the existence of cross-talk between these elements and reactive oxygen species (ROS) metabolism during cadmium stress.
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PMID:Differential expression and regulation of antioxidative enzymes by cadmium in pea plants. 1707 18

Ascorbate-glutathione systems were studied during desiccation of recalcitrant seeds of the silver maple (Acer saccharinum L.). The desiccated seeds gradually lost their germination capacity and this was strongly correlated with an increase in electrolyte leakage from seeds. Simultaneously the increase of reactive oxygen species (ROS) (superoxide radical - O(2)(-*) and hydrogen peroxide - H(2)O(2)) production was observed. The results indicate that remarkable changes in the concentrations and redox status of ascorbate and glutathione occur in embryo axes and cotyledons. After shedding, concentrations of ascorbic acid (ASA) and the reduced form of glutathione (GSH) are higher in embryo axes than in cotyledons and their redox status is high in both embryo parts. Cotyledons in freshly shed seeds are devoid of GSH. At the first stages of desiccation, up to a level of 43% of moisture content, ASA content in embryo axes and GSH content in cotyledons increased. Below this level of moisture content, the antioxidant contents as well as their redox status rapidly decreased. The enzymes of the ascorbate-glutathione pathway: ascorbate peroxidase (APX) (EC 1.11.1.11), monodehydroascorbate reductase (MR) (EC 1.6.5.4), dehydroascorbate reductase (DHAR) (EC 1.8.5.1) and glutathione reductase (GR) (EC 1.6.4.2) increased their activity during desiccation, but mainly in embryonic axes. The changes are probably required for counteracting the production of ROS during desiccation. The relationship between ascorbate and glutathione metabolism and their relevance during desiccation of recalcitrant Acer saccharinum seeds is discussed.
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PMID:Antioxidative response of ascorbate-glutathione pathway enzymes and metabolites to desiccation of recalcitrant Acer saccharinum seeds. 1712 29

Up-regulation of the antioxidant system provides protection against NaCl-induced oxidative damage in plants. Antioxidants and activity of enzymes involved in the ascorbate-glutathione (ASC-GSH) cycle in tobacco Bright Yellow-2 (BY-2) were investigated to assess the antioxidant protection offered by exogenous proline and glycinebetaine (betaine from now on) against salt stress using cells grown in suspension culture. Reduced ascorbate (ASC) was detected in BY-2 cells but dehydroascorbate (DHA) was not. Large quantities of a reduced form of glutathione (GSH) and smaller quantities of an oxidized form of glutathione (GSSG) were detected in BY-2 cells. Salt stress significantly reduced the contents of ASC and GSH as well as activities of ASC-GSH cycle enzymes such as ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR). Exogenous proline or betaine increased the activities of all enzymes except MDHAR involved in NaCl-induced ASC-GSH cycle. Levels of ASC and GSH in BY-2 cells under salt stress were lower in the presence of proline or betaine than in the absence of proline or betaine whereas there was no difference in redox status. Proline proved more effective than betaine in maintaining the activity of enzymes involved in NaCl-induced ASC-GSH cycle. Neither proline nor betaine had any direct protective effect on NaCl-induced enzyme activity involved in the antioxidant system; however, both improved salt tolerance by increasing enzyme activity. The present study, together with our earlier findings [Hoque MA, Okuma E, Banu MNA, Nakamura Y, Shimoishi Y, Murata Y. Exogenous proline mitigates the detrimental effects of salt stress more than exogenous betaine by increasing antioxidant enzyme activities. J Plant Physiol 2006;164:553-61.], suggests that proline offered greater protection against salt stress than betaine did because proline was more effective in increasing the activity of enzymes involved in the antioxidant system.
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PMID:Exogenous proline and glycinebetaine increase NaCl-induced ascorbate-glutathione cycle enzyme activities, and proline improves salt tolerance more than glycinebetaine in tobacco Bright Yellow-2 suspension-cultured cells. 1722 25

Seedlings of sweet orange (Citrus sinensis) were fertilized for 14 weeks with boron (B)-free or B-sufficient (2.5 or 10 microM H(3)BO(3)) nutrient solution every other day. Boron deficiency resulted in an overall inhibition of plant growth, with a reduction in root, stem and leaf dry weight (DW). Boron-starved leaves showed decreased CO(2) assimilation and stomatal conductance, but increased intercellular CO(2) concentrations. Activities of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), NADP-glyceraldehyde-3-phosphate dehydrogenase (NADP-GAPDH) and stromal fructose-1,6-bisphosphatase (FBPase) were lower in B-deficient leaves than in controls. Contents of glucose, fructose and starch were increased in B-deficient leaves while sucrose was decreased. Boron-deficient leaves displayed higher or similar superoxide dismutase (SOD), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDAR) and glutathione reductase (GR) activities, while dehydroascorbate reductase (DHAR) and catalase (CAT) activities were lower. Expressed on a leaf area or protein basis, B-deficient leaves showed a higher ascorbate (AsA) concentration, but a similar AsA concentration on a DW basis. For reduced glutathione (GSH), we found a similar GSH concentration on a leaf area or protein basis and an even lower content on a DW basis. Superoxide anion (O(2)(-)) generation, malondialdehyde (MDA) concentration and electrolyte leakage were higher in B-deficient than in control leaves. In conclusion, CO(2) assimilation may be feedback-regulated by the excessive accumulation of starch and hexoses in B-deficient leaves via direct interference with chloroplast function and/or indirect repression of photosynthetic enzymes. Although B-deficient leaves remain high in activity of antioxidant enzymes, their antioxidant system as a whole does not provide sufficient protection from oxidative damage.
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PMID:Boron deficiency decreases growth and photosynthesis, and increases starch and hexoses in leaves of citrus seedlings. 1819 99

Sulfur-deficient plants generate a lower yield and have a reduced nutritional value. The process of sulfur acquisition and assimilation play an integral role in plant metabolism, and response to sulfur deficiency involves a large number of plant constituents. Rice (Oryza sativa) is the second most consumed cereal grain, and the effects of sulfur deprivation in rice were analyzed by measuring changes in photosynthesis, carbohydrate metabolism, and antioxidants. The photosynthetic apparatus was severely affected under sulfur deficiency. The Chl content was reduced by 49% because of a general reduction of PSII and PSI and the associated light-harvesting antenna. The PSII efficiency was 31% lower at growth light, and the ability of PSI to photoreduce NADP+ was decreased by 61%. The Rubisco content was also significantly reduced in the sulfur-deprived plants. The imbalances between PSII and PSI, and between photosynthesis and carbon fixation led to a general over-reduction of the photosynthetic electron carriers (higher 1-q(P)). Chromatographic analysis showed that the level of monosaccharides was lower and starch content higher in the sulfur-deprived plants. In contrast, no changes in metabolite levels were found in the tricarboxylic acid or Calvin cycle. The level of the thiol-containing antioxidant, GSH, was 70% lower and the redox state was significantly more oxidized. These changes in GSH status led to an upregulation of the cytosolic isoforms of GSH reductase and monodehydroascorbate reductase. In addition, alternative antioxidants like flavonoids and anthocyanins were increased in the sulfur-deprived plants.
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PMID:Sulfur starvation in rice: the effect on photosynthesis, carbohydrate metabolism, and oxidative stress protective pathways. 1878 1

Removal of reproductive 'sink' i.e. spikelets from wheat at anthesis delays the rate of flag leaf senescence. In this work, the antioxidant defense was studied in the flag leaf of Triticum aestivum cv. Kalyansona plants showing normal (S + plants) and delayed senescence via removal of spikelets (S- plants). This was done by measurement of metabolites and activities of enzymes such as superoxide dismutase, catalase, guaiacol peroxidase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase and glutathione reductase. S- plants had higher reduced glutathione/oxidized glutathione (GSH/GSSG) ratio and antioxidant enzyme activities than the control plants and the differences were apparent from 21 days after anthesis (DAA). The removal of the reproductive sink led to an increased antioxidant defense which may be contributing towards the delayed flag leaf senescence in wheat. Chloroplasts and mitochondria, important sources of ROS, were isolated at two stages representing early (7 DAA) and late (21 DAA) senescence. Oxidative damage to proteins was studied in these organelles in relation to SOD and APX. Mitochondria had higher levels of damaged proteins than chloroplasts at 7 DAA in both S+ and S- plants. Higher damage was related to the lower antioxidant enzyme levels of SOD and APX in mitochondria as compared to chloroplasts.
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PMID:Delayed wheat flag leaf senescence due to removal of spikelets is associated with increased activities of leaf antioxidant enzymes, reduced glutathione/oxidized glutathione ratio and oxidative damage to mitochondrial proteins. 1939 42

Plant homeobox genes play an important role in plant development, including embryogenesis. Recently, the function of a class I homeobox of knox 3 gene, HBK3, has been characterized in the conifer Picea abies (L.) Karst (Norway spruce) [8]. During somatic embryogenesis, expression of HBK3 is required for the proper differentiation of proembryogenic masses into somatic embryos. This transition, fundamental for the overall embryogenic process, is accelerated in sense lines over-expressing HBK3 (HBK3-S) but precluded in antisense lines (HBK3-AS) where the expression of this gene is experimentally reduced. Altered HBK3 expression resulted in major changes of ascorbate and glutathione metabolism. During the initial phases of embryogeny the level of reduced GSH was higher in the HBK3-S lines compared to their control counterpart. An opposite profile was observed for the HBK3-AS lines where the glutathione redox state, i.e. GSH/GSH + GSSG, switched towards its oxidized form, i.e. GSSG. Very similar metabolic fluctuations were also measured for ascorbate, especially during the transition of proembryogenic masses into somatic embryos (7 days into hormone-free medium). At this stage the level of reduced ascorbate (ASC) in the HBK3-AS lines was about 75% lower compare to the untransformed line causing a switch of the ascorbate redox state, i.e. ASC/ASC + DHA + AFR, towards its oxidized forms, i.e. DHA + AFR. Changes in activities of several ascorbate and glutathione redox enzymes, including dehydroascorbate reductase (EC 1.8.5.1), ascorbate free radical reductase (EC 1.6.5.4) and glutathione reductase (GR; EC 1.6.4.2) were responsible for these metabolic differences. Data presented here suggest that HBK3 expression might regulate somatic embryo yield through alterations in glutathione and ascorbate metabolism, which have been previously implicated in controlling embryo development and maturation both in vivo and in vitro.
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PMID:Altered HBK3 expression affects glutathione and ascorbate metabolism during the early phases of Norway spruce (Picea abies) somatic embryogenesis. 1957 Jun 87


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