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)

Activity of redox-enzymes of AA system and of catalase was measured in two near-isogenic tomato lines, respectively resistant and susceptible to Tobacco Mosaic Virus infection. AFR reductase, DHA reductase and catalase showed quite similar activities in both lines, whereas AA peroxidase activity in resistant plants was 75% higher than in susceptible ones, with Km values about 4-fold lower. These data suggest that hydrogen peroxide scavenging operated by AA peroxidase could play an important role in the development of biological defence mechanisms against pathogens.
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PMID:Ascorbate peroxidase activity in resistant and susceptible plants of Lycopersicon esculentum. 129 16

Ascorbic acid content and redox-enzymes activities of AA system are determined in four population of Dasypyrum villosum adapted to live in different environments. In D. villosum from the driest and warmest environment (Pachino), AFR reductase and AA peroxidase have activities lower than in the other populations. The results point out the role of AA peroxidase as the main "scavenger" of the H2O2 produced by cell metabolism.
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PMID:Ascorbate system in Dasypyrum villosum from different environments. 181 96

Avena sativa L. grains are devoid of ascorbic acid (AA) and of oxidative enzymes (AA oxidase and AA peroxidase), while both reducing enzymes (AFR reductase and DHA reductase) are present. AA biosynthesis in the embryos starts after 12-14 hours of germination and at the same time AA peroxidase activity is detectable. During the following 14 hours the AA peroxidase activity rises up to 28 nmoles/AA oxidated/min/mg/prot. Incubation of Avena embryos with GL (the last precursor of AA according to the Isherwood biosynthetic pathway), results in both earlier AA biosynthesis and enhanced AA peroxidase activity. A 4 hour treatment is enough to induce AA synthesis and AA peroxidase elicitation. These data suggest that the development of AA peroxidase activity is controlled by AA, but they are not sufficient to clarify how that happens. Probably AA induces the synthesis of specific m-RNAs or activates enzymic precursors present in the embryos but still not working.
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PMID:[Comparison of presence of ascorbic acid and the appearance of ascorbate peroxidase activity in embryos of Avena sativa L]. 239 Feb 26

Aging of post-mitotic cells, the conidia, of Neurospora crassa is defined as the time-dependent loss of viability under a constant laboratory environment which probably resembles the organism's tropical habitat; namely, at 30 degrees C, 85-100% relative humidity under white light. Median lifespan is defined as the age at which survival of a conidial population has declined to 50% of that of a fully viable population at birth. A collection of short (age-) and long-lived (age+) mutants were previously selected from the wild-type whose median lifespan is 22 days. Thus, five groups of strains with distinct lifespans of 7, 22, 36, 50 and 60 days were defined. The purposes of the present investigation were to determine if the activities of anti-oxygenic enzymes are correlated with lifespan and to elucidate the function of the cellular longevity determinant genes. The activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) were highly-correlated with lifespan; whereas glutathione reductase and non-specific peroxidase activities were not correlated. The short-lived mutants were also deficient in cytochrome c peroxidase (CPX) and ascorbate free radical reductase (AFR), but not deficient in dehydroascorbate reductase. (These latter three enzymes were not examined in age+ mutants.) By isoelectric focusing analysis, the deficiencies of SOD, CAT, and GPX activities of age- mutants were defined in terms of specific isozymes. The mutants were specifically deficient in a cyanide-resistant mitochondrial isozyme of SOD. Sixteen age- genes, called the age-1 complex, were previously mapped on one arm of the seven chromosomes. On the basis of mapping and complementation data, it was inferred that the genes are spatially and functionally redundant. The hypothesis of functional redundancy is also supported by the enzyme data. Of seven mutants examined, representing seven of the age- genes, all were deficient in SOD, CAT and CPX, and six were deficient in AFR. Of four mutants examined, representing four of the genes, all were deficient in GPX. The results indicate a molecular basis for the previously observed photosensitivity of the mutants.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Genetically determined conidial longevity is positively correlated with superoxide dismutase, catalase, glutathione peroxidase, cytochrome c peroxidase, and ascorbate free radical reductase activities in Neurospora crassa. 631 35

The effects of ozone or sulfur dioxide on antioxidant enzymes were investigated in Arabidopsis thaliana. Plants were fumigated with 0.1-0.15 ppm ozone or sulfur dioxide up to about 1 week in an environment-controlled chamber. Both pollutants increased the activities of ascorbate peroxidase and guaiacol peroxidase in leaves, but had little effect on the activities of superoxide dismutase, catalase, monodehydroascorbate reductase, dehydroascorbate reductase or glutathione reductase. Ozone was more effective than sulfur dioxide in increasing the activities of the peroxidases. Ascorbate peroxidase activity increased 1.8-fold without a lag period during fumigation with 0.1 ppm ozone, while guaiacol peroxidase activity increased 4.4-fold with a 1-day lag. Expression of the APX1 gene encoding cytosolic ascorbate peroxidase was further investigated. Its protein levels in leaves exposed to 0.1 ppm ozone for 4 or 8 days were 1.5-fold higher than in controls. Both ozone and sulfur dioxide elevated APX1 mRNA levels in leaves at 4 and 7 days, whereas at 1 day only ozone was effective. The induction of APX1 mRNA levels by ozone (3.4- to 4.1-fold) was more prominent than that by sulfur dioxide (1.6- to 2.6-fold). The APX1 mRNA level increased by day and decreased by night. Exposure of plants to 0.1 ppm ozone enhanced the APX1 mRNA level within 3 h, which showed a diurnal rhythm similar to that of the control. These results demonstrate that near-ambient concentrations of ozone as well as similar concentrations of sulfur dioxide can induce APX1 gene expression in A. thaliana.
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PMID:Expression of Arabidopsis cytosolic ascorbate peroxidase gene in response to ozone or sulfur dioxide. 853 47

Chloroplast-targeted overexpression of an Fe superoxide dismutase (SOD) from Arabidopsis thaliana resulted in substantially increased foliar SOD activities. Ascorbate peroxidase, glutathione reductase, and monodehydroascorbate reductase activities were similar in the leaves from all of the lines, but dehydroascorbate reductase activity was increased in the leaves of the FeSOD transformants relative to untransformed controls. Foliar H2O2, ascorbate, and glutathione contents were comparable in all lines of plants. Irradiance-dependent changes in net CO2 assimilation and chlorophyll a fluorescence quenching parameters were similar in all lines both in air (21% O2) and at low (1%) O2. CO2-response curves for photosynthesis showed similar net CO2-exchange characteristics in all lines. In contrast, values of photochemical quenching declined in leaves from untransformed controls at intercellular CO2 (Ci) values below 200 microL L-1 but remained constant with decreasing Ci in leaves of FeSOD transformants. When the O2 concentration was decreased from 21 to 1%, the effect of FeSOD overexpression on photochemical quenching at limiting Ci was abolished. At high light (1000 micromol m-2 s-1) a progressive decrease in the ratio of variable (Fv) to maximal (Fm) fluorescence was observed with decreasing temperature. At 6(o)C the high-light-induced decrease in the Fv/Fm ratio was partially prevented by low O2 but values were comparable in all lines. Methyl viologen caused decreased Fv/Fm ratios, but this was less marked in the FeSOD transformants than in the untransformed controls. These observations suggest that the rate of superoxide dismutation limits flux through the Mehler-peroxidase cycle in certain conditions.
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PMID:Overexpression of iron superoxide dismutase in transformed poplar modifies the regulation of photosynthesis at low CO2 partial pressures or following exposure to the prooxidant herbicide methyl viologen. 962 9

The activities of the oxygen radical scavenging enzymes [glutathione-peroxidase (GSH-POD), superoxide dismutase (SOD), and guaiacol peroxidase (G-POD)], hydrogen peroxide scavenging enzymes in the ascorbate-glutathione cycle [ascorbate peroxidase (AsA-POD), monodehydroascorbate reductase (MDAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR)], the nonenzyme components [ascorbate (AsA), dehydroascorbate (DHAsA), glutathione (GSH), and oxidized glutathione (GSSG)], and their antioxidant capacity [oxygen radical absorbance capacity (ORAC)] were measured in the juice of six different thornless blackberry (Rubus sp.) cultivars. The 'Hull Thornless' cultivar contained the highest levels, whereas 'Black Satin' consistently had the lowest activities for all the enzymes tested in this study. ORAC values were also the highest in 'Hull Thornless' and lowest in 'Black Satin'. The highest levels of AsA and DHAsA were in the juice of 'Hull Thornless' blackberries with 1. 09 and 0.15 micromol/g fresh wt, respectively. 'Hull Thornless' also had the highest ratio of AsA/DHAsA among the six blackberry cultivars studied. The 'Smoothstem' cultivar contained the lowest amounts of AsA and DHAsA. 'Hull Thornless' had the highest GSH content with 78.7 nmol/g fresh wt, while 'Chester Thornless' contained the largest amount of GSSG. The highest GSH/GSSG ratio was 4.90 which was seen in the 'Hull Thornless' cultivar. The correlation coefficient between ORAC values and AsA/DHAsA ratios was as high as 0.972. A correlation (r = 0.901) was also detected between ORAC values and GSH content. The antioxidant activity in blackberry juice was positively correlated to the activities of most antioxidant enzymes (r = 0.902 with SOD; r = 0.858 with GSH-POD; r = 0.896 with ASA-POD; and r = 0.862 with GR).
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PMID:Correlation of antioxidant capacities to oxygen radical scavenging enzyme activities in blackberry. 1108 37

Recent evidence has indicated that activated oxygen species (AOS) may function as molecular signals in the induction of defence genes. In the present work, the response of antioxidative enzymes to the plum pox virus (PPV) was examined in two apricot (Prunus armeniaca L.) cultivars, which behaved differently against PPV infection. In the inoculated resistant cultivar (Goldrich), a decrease in catalase (CAT) as well as an increase in total superoxide dismutase (SOD) and dehydroascorbate reductase (DHAR) activities were observed. Ascorbate peroxidase (APX), glutathione reductase (GR) and monodehydroascorbate reductase (MDHAR) did not change significantly in relation to non-inoculated (control) plants. In the susceptible cultivar (Real Fino), inoculation with PPV brought about a decrease in CAT, SOD and GR, whereas a rise in APX, MDHAR and DHAR activities was found in comparison to non-inoculated (control) plants. Apricot leaves contain only CuZn-SOD isozymes, which responded differently to PPV depending on the cultivar. Goldrich leaves contained 6 SODs and both SOD 1 and SOD 2 increased in the inoculated plants. In leaves from Real Fino, 5 SODs were detected and only SOD 5 was increased in inoculated plants. The different behaviour of SODs (H2O2-generating enzymes) and APX (an H2O2-remover enzyme) in both cultivars suggests an important role for H2O2 in the response to PPV of the resistant cultivar, in which no change in APX activity was observed. This result also points to further studies in order to determine if an alternative H2O2-scavenging mechanism takes place in the resistant apricot cultivar exposed to PPV. On the other hand, the ability of the inoculated resistant cultivar to induce SOD 1 and SOD 2 as well as the important increase of DHAR seems to suggest a relationship between these activities and resistance to PPV. This is the first report about the effect of PPV infection on the antioxidative enzymes of apricot plants. It opens the way for the further studies, which are necessary for a better understanding of the role of antioxidative processes in viral infection by PPV in apricot plants.
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PMID:Response of antioxidative enzymes to plum pox virus in two apricot cultivars. 1124 Sep 15

Methylviologen (MV) induces oxidative damages in leaves. In order to understand its mechanism we studied initial biochemical events under light in MV-fed spinach leaves. When isolated chloroplasts were illuminated in the presence of MV, both stromal and thylakoid-bound ascorbate peroxidases (APX) were inactivated rapidly at the same rates, and their inactivation was retarded by ascorbate (AsA) at higher concentrations. Since MV accelerates the photoproduction of O2- in Photosystem (PS) I and simultaneously inhibits the photoreduction of monodehydroascorbate (MDA) to AsA, the inactivation of APX was attributed to the loss of AsA and accumulation of H2O2 in the stroma. Following APX, superoxide dismutase and NADP(+)-glyceraldehyde 3-phosphate dehydrogenase, both of which are vulnerable to H2O2, were inactivated by MV plus light. Dehydroascorbate reductase, monodehydroascorbate reductase, PS II, PS I and ferredoxin-NADP(+) reductase were far less sensitive to the treatment. In the treated leaves, cytosolic APX and guaiacol-specific peroxidase were also inactivated, but slower than chloroplastic APXs were. Catalase was not inactivated. Thus the MV-induced photooxidative damages of leaves are initiated with the inactivation of chloroplastic APXs and develop via the inactivation of other H2O2-sensitive targets. The decay half-life of the MDA signal after a short illumination in the leaves, as determined by in vivo electron spin resonance spectrometry (ESR), was prolonged when the H2O2-scavenging capacity of the leaf cells was abolished by the inactivation of chloroplastic and cytosolic APXs. The measurement of MDA in leaves by ESR, therefore, allows to estimate in vivo cellular capacity to scavenge the photoproduced H2O2.
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PMID:Chloroplastic ascorbate peroxidase is the primary target of methylviologen-induced photooxidative stress in spinach leaves: its relevance to monodehydroascorbate radical detected with in vivo ESR. 1124 91

Maturation and ripening of blackberry (Rubus sp.) fruit was accompanied by decreased activities of oxygen-scavenging enzymes [superoxide dismutase (EC 1.15.1.1), glutathione-peroxidase (EC 1.11.1.9), catalase (EC 1.11.1.6)] and enzymes in the ascorbate-glutathione cycle [ascorbate peroxidase (EC 1.11.1.11), monodehydroascorbate reductase (EC 1.6.5.4), dehydroascorbate reductase (EC 1.8.5.1), and glutathione reductase (EC 1.6.4.2)]. Nonenzyme components in the ascorbate-glutathione cycle such as ascorbate (AsA), dehydroascorbate (DHAsA), glutathione (GSH), and oxidized glutathione (GSSG) and the ratios of AsA/DHAsA, GSH/GSSG were also decreased. These decreases in antioxidant capacity were correlated with increases in the ratios of saturated to unsaturated fatty acid of polar lipids and free sterols to phospholipids, thus contributing to decreased fluidity, enhanced lipid peroxidation, and membrane deterioration, which may be associated with ripening and senescence in blackberry fruit.
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PMID:Changes in oxygen-scavenging systems and membrane lipid peroxidation during maturation and ripening in blackberry. 1131 4


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