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  • 1
    Electronic Resource
    Electronic Resource
    Characterization of an iron-containing superoxide dismutase from a higher plant, Citrus limonum (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 90 (1994), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: An iron-containing superoxide dismutase (SOD, EC 1.15.1.1) was fully characterized from leaves of the higher plant Citrus limonum R. cv. Verna. This enzyme is the first iron-containing SOD to be characterized in the plant family Rutaceae. The purified Fe-SOD has a molecular mass of about 47 kDa and is composed of two non-covalently joined equal subunits. The amino acid composition determined for the enzyme was compared with that of a wide range of SODs and had highest degree of homology with the Fe-SODs from Brassica campestris and Nuphar luteum. The enzyme was more labile at high temperatures than some eucaryotic and procaryotic Fe-SODs. It showed a maximum stability at pH 7.8. The sensitivity of the enzyme to cyanide, hydrogen peroxide and o-phenanthroline was similar to those reported for other Fe-SODs. but the lemon enzyme was comparatively resistant to H2O2. By kinetic competition experiments, the rate constant for the disproportionation of superoxide radicals by lemon Fe-SOD was found to be 1.9 × 109M−1 s−1 at pH 7.8 and 25°C. A comparative study between the molecular properties of this higher plant Fe-SOD and SODs from different origins is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1994.tb00397.x
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  • 2
    Electronic Resource
    Electronic Resource
    Salt-induced oxidative stress mediated by activated oxygen species in pea leaf mitochondria (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 89 (1993), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The effect in vivo of salt stress on the activated oxygen metabolism of mitochondria, was studied in leaves from two NaCl-treated cultivars of Pisum sativum L. with different sensitivity to NaCl. In mitochondria from NaCl-sensitive plants, salinity brought about a significant decrease of Mn-SOD (EC 1. 15. 1. 1) Cu, Zn-SOD I (EC 1. 15. 1. 1) and fumarase (EC 4. 2. 1. 2) activities. Conversely, in salt-tolerant plants NaCl treatment produced an increase in the mitochondrial Mn-SOD activity and, to a lesser extent, in fumarase activity. In mitochondria from both salt-treated cultivars, the internal H2O2 concentration remained unchanged. The NADH- and succinate-dependent generation of O2.−radicals by submitochondrial particles and the lipid peroxidation of mitochondrial membranes, increased as a result of salt treatment, and these changes were higher in NaCl-sensitive than in NaCl-tolerant plants. Accordingly, the enhanced rates of superoxide production by mitochondria from salt-sensitive plants were concomitant with a strong decrease in the mitochondrial Mn-SOD activity, whereas NaCl-tolerant plants appear to have a protection mechanism against salt-induced increased O2.− production by means of the induction of the mitochondrial Mn-SOD activity. These results indicate that in the subcellular toxicity of NaCl in pea plants, at the level of mitochondria, an oxidative stress mechanism mediated by superoxide radicals is involved, and also imply a function for mitochondrial Mn-SOD in the molecular mechanisms of plant tolerance to NaCl.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1993.tb01792.x
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  • 3
    Electronic Resource
    Electronic Resource
    Subcellular distribution of superoxide dismutase in leaves of ureide-producing leguminous plants (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 82 (1991), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The subcellular localization of superoxide dismutase (SOD; EC. 1.15.1.1) was studied in leaves of two ureide-producing leguminous plants (Phaseolus vulgaris L. cv. Contender and Vigna unguiculata [L.] Walp). In leaves of Vigna and Phaseolus, three superoxide dismutases were found, an Mn-SOD and two Cu, Zn-containing SODs (I and II). Chloroplasts, mitochondria, and peroxisomes were purified by differential and density-gradient centrifugation using either Percoll or sucrose gradients. The yields obtained in intact chloroplasts and peroxisomes from Vigna were considerably higher than those achieved for Phaseolus. Purified chloroplasts only contained the Cu, Zn-SOD II isozyme, but in mitochondria both Mn-SOD and Cu, Zn-SOD I isozymes were present. In purified peroxisomes no SOD activity was detected. The absence of SOD activity in leaf peroxisomes from Vigna contrasts with results reported for the amide-metabolizing legume Pisum sativum L. where the occurrence of Mn-SOD was demonstrated in leaf peroxisomes (del Río et al. 1983. Planta 158: 216–224; Sandalio et al. 1987. Plant Sci. 51: 1–8). This suggests that in leaf peroxisomes from Vigna plants the generation of O2- radicals under normal conditions probably does not take place.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1991.tb00095.x
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  • 4
    Electronic Resource
    Electronic Resource
    Isoenzyme pattern of superoxide dismutase in different varieties of citrus plants (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 76 (1989), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Superoxide dismutases (SOD; EC 1.15.1.1) in leaves from different cultivars of citrus plants were characterized using isoelectric focusing in polyacrylamide gels. The plants studied included Citrus limonum R. (cvs Verna, Fino, and Eureka), C. paradisi Mac (cvs Red Blush and Marsh), C. aurantium L. (cv. Comun), C. sinensis L. Osbeck (cvs Navel, Valencia, and Salustiano), and C. reticulata B. (cv. Satsuma). The three molecular forms of SOD were distinguished from each other by their different sensitivity to cyanide and H2O2. In C. limonum leaves, four Cu,Zn-SODs, three Fe-SODs and two Mn-SODs were present. However, in leaves from different varieties of C. sinensis, C. paradisi, C. aurantium and C. reticulata the activity and number of Fe-SOD isoenzymes were lower than in lemon leaves, whereas the number of MN-SOD isozymes was increased. Cu,Zn-SODs did not show significant variations in the different species and cultivars. The identification of Fe-SODs in several species of the plant family Rutaceae extends the small number of higher plants where the presence of these Fe-containing metalloenzymes has been demonstrated. Results obtained may be useful from an evolutionary viewpoint and also in mineral nutrition studies using SOD isozymes as markers of functional metals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1989.tb05479.x
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  • 5
    Electronic Resource
    Electronic Resource
    Superoxide dismutase: An enzyme system for the study of micronutrient interactions in plants (1978)
    Springer
    Planta 140 (1978), S. 221-225 
    Details
    ISSN: 1432-2048
    Keywords: Manganese ; Micronutrient interactions ; Pisum ; Superoxide dismutase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of different Mn levels on the isozyme pattern of superoxide dismutase was investigated. Pisum sativum L. plants were grown in nutrient solutions containing three Mn concentrations: 0.005 μg/ml (deficient), 0.05 μg/ml (low), and 0.5 μg/ml (optimum). Leaf extracts contained three electrophoretically distinct superoxide dismutases (SOD), two of which were inhibited by cyanide and were probably Cu-Zn-SODs, while the third one was CN-insensitive and could be either an Mn- or an Fe-SOD. At 0.005 μg/ml Mn supply the CN-insensitive SOD was significantly depressed at 15, 30, and 45 days of growth, whereas at 0.05 μg/ml Mn this isozyme was significantly decreased only at 45 days growth. The two CN-sensitive SODs were inversely related to the CN-resistant enzyme, the activities of the former enzymes being significantly increased at Mn-deficient levels throughout plant growth. Metal determinations of the plants showed that at low concentrations of Mn in the nutrient media, copper and zinc content of leaves increased: the lower the Mn level, the higher the increase produced. The CN-resistant SOD activity, as judged by its dependency on Mn, appears to be an Mn-SOD rather than an Fe-SOD. In the light of the results obtained, the use of the enzyme system superoxide dismutase for the study of the role and interactions between Mn, Cu, and Zn in the plant cell is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00390251
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  • 6
    Electronic Resource
    Electronic Resource
    Changes in antioxidant enzymes and organic solutes associated with adaptation of citrus cells to salt stress (1996)
    Springer
    Plant cell, tissue and organ culture 45 (1996), S. 53-60 
    Details
    ISSN: 1573-5044
    Keywords: Catalase ; cell culture ; peroxidase ; salinity ; superoxide dismutase ; Citrus limon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Embryogenic callus cultures of lemon (Citrus limon L. Burm f. cv Verna), were selected for resistance to salt stress (170 mM NaCl). Inorganic analysis showed that selected callus accumulated more Na+ and Cl- ions than the non-selected one. Moreover, the salt-tolerant C. limon callus exhibited an increase in the activity of antioxidant enzymes involved in oxygen metabolism, with the induction of a new superoxide dismutase isozyme and an increase of the peroxidase activity while the catalase activity was unchanged. Proline and total sugar, mainly sucrose, concentrations increases significantly in salt-tolerant cells as compared to control cells. On the other hand, the selected cell line also showed an increase in choline and glycine betaine, but to lesser extent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00043428
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