Ionically-bound Peroxidase Research Articles

Isolation and thermostability of peroxidase isoenzymes from apple cultivars Gala and Fuji

Extracts of soluble peroxidase and ionically-bound peroxidase were obtained from the peel and pulp of apples ( Mallus comunis), cultivars Gala and Fuji, using 100 mM sodium phosphate buffer and pH 6.0 and 7.0 for pulp and peel of Gala cultivar, respectively and pH 5.5 for the pulp and the peel of cultivar Fuji. Then the enzymatic activity of peroxidase (POD) was determined in both extracts, soluble fractions and ionically-bound. Electrophoresis results shows similar compositions for the anionic and cationic isoenzymes in both cultivars. The molecular weights and p I values of the isolated isoenzymes from the Fuji cultivar were: two anionic, A 1 and A 2 (38, 28 kDa and p I 4.4; 5.0, respectively) and three cationic C 1, C 2 and C 3 (40, 34, 26 kDa and p I 8.0, 8.3, 9.0, respectively). From the Gala cultivar, also, two anionic isoenzymes were isolated A 2 and A 4 (28, 26 kDa and p I 5.0 and 5.7, respectively) and three cationic isoenzymes C 1, C 2 and C 3 (40, 34, 26 kDa and p I 8.0, 8.3 and 9.0, respectively). The cationic isoenzymes were more heat-stable under the heat treatments at 65, 70, 75 and 80 °C in both cultivars.

Ecophysiological approach to study of the role of cell-bound peroxidase forms in wheat leaves of different morphology

Extracellular peroxidase enzymes, both ionically - and covalently bound, have been implicated in the biochemical changes of cell wall and furthermore for regulation of leaf and root extension growth. However, the role of cell wall bound peroxidase in changes of mature leaf morphology is poorly understood. The aim of this study was to determine whether ionically and covalently bound peroxidase activities exhibit any relationships with drought-induced leaf rolling of wheat. An activity and thermostability of three wheat genotypes with different leaf rolling degree were studied. The results clearly show that two genotypes with leaf rolling trait exhibited significantly higher activity of both extracellular peroxidase fractions in comparison to non-rolling cv. 'Omskaya 9'. In addition, the significant genotypic differences were found in thermostability of ionically and covalently bound peroxidase. A 35 °C-treatment decreased the activity of ionically bound peroxidase (IBP) in non-rolling leaves of parent cultivar and enhanced the activity of IBP in rolling leaves of 'Alba' genotype. Under 45 and 55 °C-treatment the IBP was more stable in rolling leaves of both genotypes 'Otan' and 'Alba'. Despite to low activity of covalently bound peroxidase it was more stable after heating by 45 °C compare with ionically bound fraction. The heating of covalently bound peroxidase (CBP) extracts by 35 °C and 45 °C also has enhancing effect on its activity by both leaf rolling genotypes (on 16 and 40% by 'Otan' and 'Alba', respectively). At the same time the CBP activity of non-rolling genotype decreased significantly on 40%. Even after 55 °C-treatment the CBP of both rolling genotypes remained very stable, although there were further inhibition of CBP purificated from leaves of non-rolling genotype. Both wheat genotypes with inserted leaf rolling trait exhibited a much higher blue-green fluorescence emission than non-rolling leaves of parent cultivar 'Omskaya 9'. Thus, the molecular mechanism of leaf rolling regulation seems to include an adjustment of cell wall properties and probably involves an activity of cell wall bound peroxidase. Further investigation is expected to reveal the regulatory mechanism for leaf rolling in wheat.

Dry mycelium ofPenicillium chrysogenum induces resistance against verticillium wilt and enhances growth of cotton plants

Dry mycelium (DM) ofPenicillium chrysogenum and its water extract (DME) were examined for their effects on induced resistance against Verticillium wilt and plant growth of cotton in the greenhouse. Soil application of 0.1–5% DM or 0.5–5% DME provided significant protection against the wilt, relative to the control. As neither DM nor DME inhibited mycelial growth ofVerticillium dahliae in vitro, it is suggested that the disease-controlling effects of DM or DME are attributed to induced resistance. DME (5%), as well as DME treated with chloroform or cold acetone, were as effective as 2% DM in reducing disease severity of Verticillium wilt, implying that the resistance-inducing substance(s) in DM are mostly water-soluble, with neither proteins nor lipids likely to be responsible for the induction of resistance. No significant difference in root colonization withV. dahliae was found between control-inoculated and 2% DM- or 5% DME-inoculated plants. However, colonization of hypocotyls and epicotyls was drastically suppressed by either 2% DM or 5% DME relative to the control. Treatments with 2% DM or 5% DME significantly increased ionically-bound peroxidase (POX) activity in roots, hypocotyls and the second leaf of cotton plants, with the hypocotyls expressing the highest increase. Soil application of DM or DME increased plant height, fresh and dry weight of inoculated and non-inoculated cotton plants, relative to their corresponding controls. It is concluded that DM may be used in cotton crops to promote plant growth and to induce resistance againstV. dahliae. POX might be associated with the defense against Verticillium wilt.

Peroxidases and photosynthetic pigments in susceptible potato infected with potato virus Y NTN

The aim of this work was to investigate the activity of soluble, ionically- and covalently-bound peroxidases (EC 1.11.1.7), the protein content, and the photosynthetic pigment metabolism in the potato ( Solanum tuberosum L.) cv. Igor, at the time of local lesion development resulting from infection with potato virus Y NTN. In comparison to intact plants, mock inoculation with the sap of healthy plants induced changes in peroxidase activity and metabolism of photosynthetic pigments which could, in most cases, be distinguished from the changes induced by virus infection. An inverse correlation was observed between chlorophyll content and the activity of soluble and ionically-bound peroxidases. This activity increased while that of covalently-bound peroxidase decreased, even in green leaves of infected plants which were visibly unchanged, as well as in green leaves with local lesions. Lower chlorophyll content, and higher carotenoid to chlorophyll ratio than those in intact and mock-inoculated controls – signs of senescence – were observed in leaves with local lesions and in yellow leaves of infected plants. Differences in measured parameters in intact, mock-inoculated, and infected plants showed that processes induced by virus infection differ from those induced by mock inoculation, and that viral induced senescence is clearly not the same as natural senescence.

Substrate-Specific Peroxidases in Woody Angiosperms and Gymnosperms Participate in Regulating the Dehydrogenative Polymerization of Syringyl and Guaiacyl Type Lignins

Substrate specificities of enzymes involved in monolignol biosynthesis are recognized to control differentiation of guaiacyl and syringyl lignin, but peroxidases are regarded to have rather less substrate specificity and their specificity related to lignification has not been fully elucidated. We have investigated the substrate specificity of peroxidases (EC1.11.1.7) in poplar (Populus alba L.) and Japanese cedar (Cryptomeria japonica D. Don) with respect to the dehydrogenative polymerization of monolignols. Peroxidases were fractionated into three groups, namely soluble peroxidases ionically bound peroxidases (IPO). and covalently bound peroxidases. Populus IPO was found to have the largest preference for sinapyl alcohol among all of peroxidases from both woody plant species, and only this peroxidase could produce the dehydrogenative polymer (DHP) from sinapyl alcohol. On the other hand. all peroxidases from both Cryptomeria and Populus easily produced the DHP from coniferyl alcohol. The results support that the participation of substrate-specific peroxidases is an important factor regulating the accumulation of syringyl and guaiacyl lignins in angiosperms and gymnosperms. Electrophoresis of IPO revealed the existence of syringyl-specific isoperoxidase only in Populus IPO.

Phenolic accumulation and peroxidase activity inin vitro selected alfalfa callus cultures resistant to filtrate ofFusarium spp.

Changes in the phenylalanine ammonia-lyase (PAL) activity, accumulation of phenolic acids and ionically-bound peroxidase activity in thein vitro selected embryogenic and nonembryogenicMedicago sativa callus cultures resistant to the filtrate ofFusarium spp. were found. The PAL activity in bothin vitro selected cultures during a 4-week cultivation on a medium with phytotoxins was higher than in the control calli grown on a medium without toxin. The filtrate fromFusarium spp. evoked an increase in the contents of all determined phenolic acids in the selected calli. They occurred predominantly bound as esters. The most pronounced portions in the elevated acids level were of ester-bound p-hydroxybenzoic, vanillic, p-coumaric and ferulic acids. The ionic cell wall-bound peroxidase activity in both selected calli cultivated on a medium with a filtrate was twice as high as the activity determined in the control cultures. The activity of soluble peroxidase was not influenced by challenge with a filtrate. No significant differences were found between thein vitro selected embryogenic and nonembryogenic alfalfa callus cultures in the response to the phytotoxic filtrate.

The occurrence of isoperoxidases in conference pears

SummarySoluble and ionically‐bound peroxidases have been obtained from the pulp and peel of Conference pears. The peel soluble fraction contained the highest level of peroxidase activity. The peel peroxidases, both soluble and ionically bound, were particularly heat stable. Following heat inactivation, regeneration of enzymic activity was observed for the peel peroxidases and soluble pulp enzymes. Plots of the percentage of heat inactivation for the pear peroxidases against heating time were non‐linear.

Early effects of excess cadmium uptake in Phaseolus vulgaris.

Abstract. Seedlings of Phaseolus vulgaris were exposed to solutions containing Cd2+ in the range 0 to 1 molm−3. Ethylene formation started following 3 h of exposure to 10−2, 10−1 and 1 mol m−3 Cd2+, peaked at 18 h and returned to a relatively low rate after 24 h. Cadmium-induced ethylene formation depended on the formation of 1-aminocyclopropane-1-carboxylic acid (ACC). Aminoethoxyvinylglycine (AVG, 0.1 mol m−3) inhibited ACC accumulation and ethylene production during exposure to 0.2 mol m−3 Cd2+. Activity of soluble and ionically-bound peroxidase increased after 18 h of exposure to Cd2+ concentrations above 10−3 mol m−3 due to an increase in activity of cathodic isoperoxidases. Stimulation of soluble and ionically-bound peroxidase by 0.2 mol m−3 Cd2+ was reduced in the presence of 0.1 mol m−3 AVG. Accumulation of soluble and insoluble (‘ligninlike’) phenolics was found in plants exposed to Cd2+ (10−2 mol m−3 or above) in the presence or absence of AVG. Deposition of insoluble (autofluorescing) material occurred in cell walls around vessels and was associated with reduced expansion and water content of leaves.