Partial purification and characterization of a copper-induced anionic peroxidase of sunflower roots

Abstract

Treatment of 14-day-old sunflower seedlings with a toxic amount of copper (50 microM of CuSO(4)) during 5days caused significant increase in peroxidase activity in roots. Qualitative analysis of soluble proteins using native anionic PAGE followed by detection of peroxidase activity with guaïacol as electron donor in the presence of H(2)O(2) revealed five stimulated peroxidases, named A1, A2, A3, A4, and A5. These peroxidases had differential behavior during the period of treatment. A1, A2, A3 and A4 were stimulated in the first period of stress, but rapidly suppressed at 72h. A5 showed a progressive stimulation which was even increased at 120h. A1 was partially purified, identified using liquid chromatography coupled to mass spectrometry (LC-MS/MS), and characterized. Effects of pH and temperature on its activity were determined with guaïacol as electron donor. Optima were obtained at pH 8 and at 40 degrees C. Analysis of substrate specificity showed that A1 was active on coniferyl alcohol but not on IAA. Enzymatic activity was inhibited by a high concentration of H(2)O(2).

Biochemical characterization of a peroxidase isolated from Caribbean plant: Euphorbia cotinifolia

“…Purified enzyme (25 g) from the homogenous pool fractions (30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45) were mixed with sample loading buffer and loaded on 12.5% SDS-PAGE under both non-reducing and reducing conditions [20]. The gels were stained with 0.2% Coomassie brilliant blue R-250.…”

“…catalyze the formation of harmful free radicals, which causes an oxidative burst and this effect can be improved by anti oxidative systems including peroxidase, e.g. sunflower seeding treated with CuSO 4 [31]. The conformational changes of CCPP under native and denatured GuHCl and urea conditions were studied by fluorescence and circular dichroism.…”

Protein and Peroxidase Modulations in Sunflower Seedlings (Helianthus annuus L.) Treated with a Toxic Amount of Aluminium

“…Under stress conditions, we observed a stimulation of A2 and A3 in leaves and A1 in roots. In a previous study [20], we have demonstrated that cupric stress enhanced significantly all root isozymes especially A5, this effect is not observed in Al treatment which spectacularly enhanced A1. Thus, it appears that quantitative stimulation of peroxidase activity under metallic stress conditions was not corresponding to the activation of same isoforms.…”

“…For sunflower, one of metal hyperaccumulator plants, data on changes in metabolic processes as a result of exposure to Cu, Cd, Fe and Ni reveal a decrease in growth accompanied with significant stimulation of peroxidases activities [11,18,19]. Recently, we have demonstrated that Cu treatment caused the stimulation of a moderately anionic peroxidase (pI=6.7) that was identified and characterised [20]. Here, we examined the peroxidases responses to Al treatment for comparing the Al-induced changes with those caused by other metals in order to fully understand the role of peroxidases in defence mechanisms against metal stress.…”

Purification and Characterization of Peroxidase From Fresh-Cut Zizania Latifolia

“…4, the activity of purified POD maintained relatively high in the temperature range between 20 and 50C and presented a maximum at 40C. For comparison, it can be stated that the optimum temperature for activity of sunflower roots POD, using coniferyl alcohol as substrate, is also 40C (Jouili et al . 2008).…”