Copper-zinc superoxide dismutase is a constituent enzyme of the matrix of peroxisomes in the cotyledons of oilseed plants (original) (raw)
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PLANT PHYSIOLOGY, 1988
The intraorganellar distribution of superoxide dismutase (SOD) (EC 1.15.1.1) in two types of plant peroxisomes (glyoxysomes and leaf peroxisomes) was studied by determinations of SOD latency in intact organelles and by solubilization assays with 0.2 molar KCI. Glyoxysomes were purified from watermelon (Citrullus vulgaris Schrad.) cotyledons, and their integrity, calculated on the basis of glyoxysomal marker enzymes, was about 60%. Under the same conditions, the latency of SOD activity determined in glyoxysomes was 40%. The difference between glyoxysomal intactness and SOD latency was very close to the percentage of isozyme Mn-SOD previously determined in glyoxysomes (LM Sandalio, LA Del Rio 1987 J Plant Physiol 127: 395409). In matrix and membrane fractions of glyoxysomes, SOD exhibited a solubilization pattern very similar to catalase, a typical soluble enzyme of glyoxysomes. The analysis of the distribution of individual SOD isozymes in glyoxysomal fractions treated with KCI showed that Cu,Zn-SOD II, the major SOD isozyme in glyoxysomes, was present in the soluble fraction of these organelles, whereas Mn-SOD was bound to the glyoxysomal membrane. These data in conjunction with those of latency of SOD activity in intact glyoxysomes suggest that Mn-SOD is bound to the external side of the membrane of glyoxysomes. On the other hand, in intact leaf peroxisomes where only a Mn-containing SOD is present (LM Sandalio, JM Palma, LA Del Rio 1987 Plant Sci 51: 1-8), this isozyme was found in the peroxisomal matrix. The physiological meaning of SOD localization in matrix and membrane fractions of glyoxysomes and the possibility of new roles for plant peroxisomes in cellular metabolism related to activated oxygen species is discussed.
Plant Molecular Biology, 1990
A cDNA library from ethephon-treated cucumber cotyledons (Cucumis sativus L. cv. Poinsett 76) was constructed. Two cDNA clones encoding putative peroxidases were isolated by means of a synthetic probe based on a partial amino acid sequence of a 33 kDa cationic peroxidase that had been previously shown to be induced by ethylene. DNA sequencing indicates that the two clones were derived from two closely related RNA species that are related to published plant peroxidase sequences. Southern analysis indicates that there are 1-5 copies in a haploid genome of a gene homologous to the cDNA clones. The deduced amino acid sequences are homologous with a tobacco (55 ~o sequence identity), a horseradish (539/o), a turnip (45 ~o ), and a potato (419/o ) peroxidase. The cloned sequences do not encode the 33 kDa peroxidase from which the original synthetic probe was been derived, but rather other putative peroxidases. An increase in the level of mRNA is evident by 3 hours after ethephon or ethylene treatment and plateaus by 15 hours.
Characterization of Peroxidase in Plant Cells
PLANT PHYSIOLOGY, 1984
Two peroxidases, one anionic and one cationic, have been purified from the proteins secreted by peanut (Arachis hypogaea L. var Virginia 56R) cells in suspension culture. These two peroxidases apparently have identical catalytic properties. www.plant.org on May 17, 2016 -Published by www.plantphysiol.org Downloaded from
Journal of Experimental Botany, 2007
In this work the manganese superoxide dismutase (Mn-SOD) bound to peroxisomal membranes of watermelon cotyledons (Citrullus lanatus Schrad.) was purified to homogeneity and some of its molecular properties were determined. The stepwise purification procedure consisted of ammonium sulphate fractionation, batch anion-exchange chromatography, and anion-exchange and gel-filtration column chromatography using a fast protein liquid chromatography system. Peroxisomal membrane Mn-SOD (perMn-SOD; EC 1.15.1.1) was purified 5600-fold with a yield of 2.6 mg of enzyme g 21 of cotyledons, and had a specific activity of 480 U mg 21 of protein. The native molecular mass determined for perMn-SOD was 108 000 Da, and it was composed of four equal subunits of 27 kDa, which indicates that perMn-SOD is a homotetramer. Ultraviolet and visible absorption spectra of the enzyme showed a shoulder at 275 nm and two absorption maxima at 448 nm and 555 nm, respectively. By isoelectric focusing, a pI of 5.75 was determined for perMn-SOD. In immunoblot assays, purified perMn-SOD was recognized by a polyclonal antibody against Mn-SOD from pea leaves, and the peroxisomal enzyme rapidly dissociated in the presence of dithiothreitol and SDS. The potential binding of the Mn-SOD isozyme to the peroxisomal membrane was confirmed by immunoelectron microscopy analysis. The properties of perMn-SOD and the mitMn-SOD are compared and the possible function in peroxisomal membranes of the peripheral protein Mn-SOD is discussed.
Protoplasma, 2005
The analysis of plasma membranes from maize roots by native gel electrophoresis revealed the existence of Mn-containing 120 kDa and CuZn-containing 70, 40, and 15 kDa superoxide dismutase (SOD) isoform activities. Isoelectric focusing of the plasma membranes differentiated anionic SOD isoforms with a pI of about 5 and cationic SOD isoforms at pI 8.6. Solubilization of the plasma membrane proteins further separated the cationic SOD into pI 8.6, 8.2, 8.4, and 7.2 isoforms. Double staining for both SOD and peroxidase activities showed an overlap of these activities only in the case of the high-molecular-mass (ca. 120 kDa) isoforms. High-temperature treatments demonstrated that the 120 kDa isoform was active even at 100 ЊC, indicating that it was a germin-like protein with superoxide-dismutating activity, different from the peroxidase with a similar molecular mass and the lower-molecular-mass CuZn-containing superoxide dismutases. These results are compared to those obtained from whole-tissue extract and apoplastic fluid.
Plant peroxidases: Interaction between their prosthetic groups
Phytochemistry, 1994
The function of the prosthetic groups of cationic peanut peroxidase protoporphyrin IX (heme), calcium and carbohydrates is reviewed. The interactions among them and with the polypeptide, i.e. their role in the maintenance of the tertiary structure, and the stability of this complex enzyme are analysed. Findings regarding the appearance of forms with a different degree of glycosylation, their significance in the enzyme stability, and enhancement of the turnover rate in oiuo are discussed. Removal of calcium ions and their replacement by cadmium ions is used as a model to study alterations in the protein conformation. The electronic structures of the primary compounds of the cationic isozyme of peanut peroxidase and horseradish peroxidase isozyme c are analysed and compared to that of beef liver catalase. The possibility of involvement of manganese ions in the catalytic cycle of a plant peroxidase is discussed. The localization in I;ir;o of the cationic and anionic major isozymes of peanut peroxidase and their kinetic parameters for different substrates are described. Their physiological roles in plant growth and development, as well as their involvement in defense mechanisms in environmental stress conditions are reviewed.
Induction of 33-kD and 60-kD Peroxidases during Ethylene-Induced Senescence of Cucumber Cotyledons
PLANT PHYSIOLOGY, 1988
Ethylene enhanced the senescence of cucumber (Cucumis sativus L. cv 'Poinsett 76') cotyledons. The effect of 10 microliters per liter ethylene was inhibited by 1 millimolar silver thiosulfate, an inhibitor of ethylene action. An increase in proteins with molecular weights of 33 to 30 kilodaltons and lower molecular weights (25,, and 10 kilodaltons) were observed in sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels after ethylene enhanced senescence. The measurement of DNase and RNase activity in gels indicated that these new proteins were not nucleases. Two proteins from ethylene-treated cotyledons were purified on the basis of their association with a red chromaphore and subsequently were identified as peroxidases. The molecular weights and isoelectric points (pI) of two of these peroxidases were 33 kilodaltons (cationic, pl = 8.9) and 60 kilodaltons (anionic, pI = 4.0). The observation that V5S1Na2SO4 was incorporated into these proteins during ethylene-enhanced senescence suggests that these peroxidases represent newly synthesized proteins. Antibodies to the 33-kilodalton peroxidase precipitated two in vitro translation products from RNA isolated from ethylene-treated but not from control cucumber seedlings. This indicates that the increase in 33-kilodalton peroxidase activity represents de novo protein synthesis. Both forms of peroxidase degraded chlorophyll in vitro, which is consistent with the hypothesis that peroxidases have catabolic or scavenging functions in senescent tissues.
Plant peroxidases : biochemistry and physiology
1996
Resistant (Reba B50) and susceptible (Acala 44) cotton plants were investigated for intratissular growth of bacterial populations and peroxidase (POx) activity, after infection of cotyledons with races 18 or 20 from #Xanthomonas (#Axonopodis$) campestris$ pv. #malvacearum$. Considerable multiplication of the bacterial population was noticed in the compatible interaction (Acala 44 / Xcm race 18) ; it was much lower during the incompatible interaction when race 18 was infiltrated into cotyledons of Reba B50. An intermediate level of bacterial growth was obtained when Reba B50 was infiltrated with race known to overcome resistance of this line. High increase in POx activity occurred into the infected cotyledons during incompatible interaction, while the increase was much lower when the interactions were compatible. On leaves, a similar and significant difference in enzyme activity was also observed indicating that the "peroxidase response" was systemically induced in entire r...