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PubMed1991

Paraquat-resistant HeLa cells: increased cellular content of glutathione peroxidase.

Paraquat-resistant HeLa cells were selected and characterized to determine the mechanism(s) of the toxic action of paraquat for cultured mammalian cells. From HeLa cells already selected for resistance to the toxicity of 40 microM paraquat more resistant cells were selected in 90 microM paraquat. In these more resistant cells (PQRHM90) one adaptation which occurred at the lesser concentration of paraquat, magnification of the cellular content of both the CuZn- and the Mn-containing superoxide dismutases, did not increase further. Instead, the cellular content of catalase and of glutathione peroxidase increased. The increased cellular content of glutathione peroxidase appeared more likely to have produced increased resistance to paraquat than did the augmented content of catalase because, after cultivation in the absence of paraquat, the cells retained both resistance to 90 microM paraquat and the increased content of glutathione peroxidase, while the content of catalase declined. The cellular content of reduced glutathione in the PQRHM90 cells grown in paraquat was diminished in comparison with that in the cells from which they derived. The data suggest that the PQRHM90 cells resisted the toxicity of paraquat by increasing the cellular activity of glutathione peroxidase as a means of detoxifying the H2O2 produced by paraquat.

Catalase↗
PubMed1991

Oxidation of methoxybenzenes by manganese peroxidase and by Mn3+.

Manganese peroxidase, produced by some white-rot fungi during lignin degradation, catalyzes the oxidation of Mn2+ to Mn3+. Whereas Mn3+ is known to oxidize phenolic compounds, its role in lignin degradation is not clear. We have used a series of methoxybenzenes with E1/2 values of 1.76-0.81 V (vs saturated calomel electrode) to investigate the oxidizing ability of Mn3+ chelates generated chemically and enzymatically. Although lignin peroxidase has been shown to oxidize high potential congeners, our results show that manganese peroxidase, or physiological concentrations of Mn3+, oxidize only the lower potential congeners. In addition, Mn3+ increased the rate of decay of the cation radical of 1,2,4,5-tetramethoxybenzene. The kinetics of decay continued to be first order, so Mn3+ does not oxidize the cation radical itself, but probably oxidizes a neutral dienyl radical derived from the cation radical. This indicates a possible role for Mn3+ in lignin degradation, as neutral dienyl radicals are proposed to be products of lignin peroxidase action.

Anisoles↗
PubMed1992

Horseradish peroxidase-catalyzed aerobic oxidation and peroxidation of indole-3-acetic acid. I. Optical spectra.

A study of the indole-3-acetate reaction with horse-radish peroxidase, in the absence or presence of hydrogen peroxide, has been performed, employing rapid scan and conventional spectrophotometry. We present here the first clear spectral evidence, obtained on the millisecond time scale, indicating that at pH 5.0 and for high [enzyme/substrate] ratios peroxidase compound III is formed. Most, if not all, of the compound III is formed by oxygenation of the ferrous peroxidase. There is an inhibitory effect of superoxide dismutase and histidine on compound III formation which indicates the involvement of the active oxygen species superoxide and singlet oxygen. It is concluded that the oxidation of indole-3-acetate by horseradish peroxidase at pH 5.0 proceeds through compound III formation to the catalytically inactive forms P-670 and P-630. A reaction path in which the enzyme is directly reduced by indole-3-acetate might be involved as an initiation step. Rapid scan spectral data, which indicate differences in the formation and decay of enzyme intermediate compounds at pH 7.0, in comparison with those observed at pH 5.0, are also presented. At pH 7.0 compound II is a key intermediate in oxidation--peroxidation of substrate. Mechanisms of reactions consistent with the experimental data are proposed and discussed.

Aerobiosis↗
PubMed1992

Selenium-dependent glutathione peroxidases from ovine and bovine erythrocytes occur as longer chain forms than previously recognized.

From the cDNA sequence of bovine glutathione peroxidase [G. T. Mullenbach, A. Tabrizi, B. D. Irvine, G. I. Bell, J. A. Tainer, and R. A. Hallewell (1988) Protein Eng. 2, 239-246], it is known that the full transcript represents a 205-residue protein with the N-terminal sequence of MCAAQRSAAALAAAAPRTV. However, a protein primary structure determination on what is believed to be the mature protein showed an N-terminal sequence of AAALAAAAPRTV [W. A. Günzler, G. J. Steffens, A. Grossmann, S. A. Kim, F. Otting, A. Wendel, and L. Flohe (1984) Hoppe-Seyler's Z. Physiol. Chem. 365, 195-212], suggesting processing of the N-terminal 7 residues to give the mature protein. It is shown here that the normal form of bovine erythrocyte glutathione peroxidase is most likely the full transcript lacking the N-terminal methionine, and that subsequent proteolysis during isolation results in formation first of the form characterized by Günzler et al. and then of two slightly smaller species, the smaller of which appears to be similar to that examined crystallographically [O. Epp, R. Ladenstein, and A. Wendel (1983) Eur. J. Biochem. 133, 51-69]. For ovine erythrocyte glutathione peroxidase the same behavior is seen, with initial isolation of a high-molecular-weight form that is subsequently proteolyzed to two intermediate forms and a final form that migrates at the same position on acrylamide gels as the lowest-molecular-weight form of the bovine enzyme. The contaminating protease can be inhibited by the addition of 10 mM EDTA, suggesting that it is a metalloprotease. Activity measurements on the intact and processed forms of the ovine enzyme show no significant differences with both hydrogen peroxide and t-butyl hydroperoxide as substrates. These results suggest that both bovine and ovine erythrocyte glutathione peroxidases consist of a globular core that is relatively resistant to proteolysis and an N-terminal tail of approximately 17 residues that seems to be exposed and is very sensitive to proteolysis. This tail, which contains many hydrophobic residues, is predicted to be largely alpha-helical and may be involved in anchoring the enzyme at or close to the membrane surface.

Amino Acid Sequence↗
PubMed1983

Effect on peroxidase activity and specific binding of the hormone 17 beta-oestradiol and rat salivary glands.

The effect was studied on immature and adult female rats. Oestradiol, given either once (10 micrograms) or three times (3 X 10 micrograms) subcutaneously significantly retarded the total weight gain of immature rats whereas, at the same time, the weight of the uteri increased several fold. The weights of neither salivary nor lacrimal glands were dependent on oestradiol. The activity of the peroxidase enzyme, a marker of oestrogen-responsive tissues, increased significantly in the rat uteri but had no effect on lacrimal peroxidase. The levels of rat salivary peroxidase increased during oestradiol administration with considerable differences between various glands. The increase in peroxidase activities could not be explained by changes in the total protein content but seemed to be specific for this enzyme. Experiments using [3H]-oestradiol indicated specific binding to uterus, parotid and submandibular glands. It is concluded that rat salivary glands are oestrogen-responsive.

Animals↗
PubMed1994

Circular dichroism studies of the binding of mammalian and non-mammalian cytochromes c to cytochrome c oxidase, cytochrome c peroxidase, and polyanions.

The effects of binding of Candida krusei, Drosophila melanogaster, horse, human, and rat cytochromes c to beef cytochrome c oxidase (ferrocytochrome c: oxygen oxidoreductase, EC 1.9.3.1) and yeast cytochrome c peroxidase (ferricytochrome c: hydrogen-peroxide oxidoreductase, EC 1.11.1.5) on their circular dichroism spectra were determined. The binding to cytochrome oxidase results in a positive increase in the ellipticities of the positive and negative Cotton effects at 404 nm and 417 nm of cytochrome c. The horse, human, and rat cytochromes c display less of an increase in the ellipticity of the positive Cotton effect at 404 nm, but more of a positive change in the negative Cotton effect at 417 nm than the C. krusei or D. melanogaster proteins. Interaction with yeast cytochrome c peroxidase elicits only a positive change in the ellipticity of the positive Cotton effect at 404 nm. No significant change is observed in the negative Cotton effect at 417 nm. Rat cytochrome c variants with a phenylalanine in place of tyrosine-67 and/or an alanine in place of proline-30 all display circular dichroism spectral changes upon binding to cytochrome c oxidase or cytochrome c peroxidase identical to those of the unaltered protein. The increase in ellipticity at 404 nm upon binding occurs even though replacement of tyrosine-67 results in the loss of the positive Cotton effect at this position. Polyglutamate and phosvitin complexes of cytochrome c show changes in the circular dichroism spectrum similar to those observed with cytochrome c peroxidase. However, the magnitudes of the spectral changes were considerably less. A model is proposed in which the main cause of the circular dichroism spectral changes observed upon complexation arise from the exclusion of solvent from the exposed front heme edge. According to this model, the exclusion of solvent changes the relative asymmetry of the environment of the electronic transitions of the heme prosthetic group of cytochrome c, resulting in observed circular dichroic effects.

Animals↗
PubMed1977

Partition of catalase and its peroxidase activities in human red cell membrane: effect of ATP depletion.

Partititon of catalase (hydrogen-peroxide:hydrogen-peroxide oxidoreductase EC 1.11.1.6) and peroxidase (donor:hydrogen-peroxide oxidoreductase EC 1.11.1.7) activities between the red cell membrane and the cytosol were studied under various experimental conditions. A small but significant amount of catalase (1.6%) was retained on human red cell membranes prepared by hemolysing washed red cells with 30 volumes of 10 mM Tris buffer, pH 7.4. Membrane -bound catalase had a relatively higher peroxidase activity than the soluble enzyme fraction. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate of the solubilized membranes demonstrated catalase to be a single band with a molecular weight of 60 000. Membranes prepared from adenosine triphosphate-depleted red cells depicted a two to three-fold increase in catalase activity, as well as an increase in 60 000 molecular weight band on polyacrylamide gel electrophoresis. The extra amount of retained catalase was a less efficient peroxidase than found in fresh membranes. The binding of catalase to ATP-depleted red cell membranes was dependent upon both pH and hemolysing ratio. Red cells incubated at pH 7.1 demonstrated a decrease in bound catalase, as did membranes prepared from red cells hemolysed at 1:100 dilution. beta-Mercaptoethanol decreased the catalase activity in the membranes and increased the odianisidine peroxidase activity without any significant effect on the 60 000-dalton band.

Adenosine Triphosphate↗
PubMed1996

Modulation of glutathione peroxidase activity in human vascular endothelial cells by fatty acids and the cytokine interleukin-1 beta.

Objectives of this study were (a) to assess the extent of oxidative stress elicited in human endothelial cells by n-3, n-6 and n-9 mono- and polyunsaturated fatty acids and by interleukin-1 beta and (b) to determine how such stress influenced glutathione peroxidase (GSHPx) activity. Fatty acids were co-incubated with human vascular endothelial cells (HUVEC) for 24 h. Lipid peroxidation, monitored as conjugated diene (CD) formation, increased 3-4-fold with increasing eicosapentaenoic and docosahexaenoic acids: 2-3-fold with linoleic acid; decreased by 50% with arachidonic acid and was unchanged with oleic acid. Changes in glutathione peroxidase activity mirrored conjugated diene formation in the HUVEC incubated with fatty acids. Interleukin-1 beta also increased glutathione peroxidase and conjugated diene formation; the latter increased enzyme activity dose-dependently suggesting a possible role for this oxidation product in the induction of glutathione peroxidase activity. The ability of fish oil fatty acids to induce antioxidant enzymes, particularly those of the glutathione redox system, may be an important mechanism protecting cells and tissues against oxidative and inflammatory cytokine elicited damage.

Arachidonic Acid↗
PubMed1991

Heterologous expression of active manganese peroxidase from Phanerochaete chrysosporium using the baculovirus expression system.

The cDNA encoding Mn peroxidase isozyme H4 from Phanerochaete chrysosporium was recombined into a baculovirus and heterologously expressed in Sf9 cells. The recombinant Mn peroxidase has the same molecular weight as the native enzyme as determined by SDS-PAGE and cross-reacts with a Mn peroxidase-specific antibody. The recombinant enzyme has a slightly lower pI than the native fungal isozyme H4 indicating some differences in post-translational modification. Phenol red, guaiacol, and vanillylacetone, substrates of the native Mn peroxidase, are oxidized by the recombinant enzyme. All of the activities are dependent on both Mn (II) and H2O2.

Baculoviridae↗
PubMed1988

A comparative study of the effects of chronic axotomy, crush lesion and re-anastomosis of the rat sural nerve on horseradish peroxidase labelling of primary sensory neurons.

Chronic axotomy is detrimental to the incorporation of horseradish peroxidase (HRP) by neurons of the central and peripheral nervous system. Using the rat sural nerve as a model, this study aimed to determine the effects of other types of nerve injury on the peroxidase labelling of dorsal root ganglion (DRG) cells. Compared to the decreased labelling occurring shortly after permanent transection of the sural axons at the ankle, crush injury of the nerve had no effect on the number and size distribution of peroxidase-stained cells. Re-anastomosing the sural nerve to its own distal segment or to the tibial nerve delayed the changes in HRP neuronal labelling, which subsequently were less severe in neurons allowed to reinnervate their own nerve. It also sustained the incorporation of HRP by many large DRG neurons, a function which is lost shortly after these cells are chronically axotomized. Nerve re-anastomosis also prevented the retrograde atrophy of myelinated and unmyelinated nerve fibers which is triggered by permanent transection. Based on the preservation of fiber counts in the sural nerves proximal to the site of surgery, with no evidence of degeneration, our observations possibly reflect alterations in the peroxidase metabolism of DRG neurons depending on the type of axonal injury they sustained and the possibility they had upon regeneration to contact endoneurial tubes and ultimately their original end-organs.

Animals↗
PubMed1990

Glial peroxidase activity in the hypothalamic arcuate nucleus: effects of estradiol valerate-induced persistent estrus.

To test the hypothesis that stimulation of glial peroxidase activity by estrogens may play a role in the pathogenesis of the previously reported degenerative changes in the hypothalamic arcuate nucleus that occur in female rats treated with a long-acting estrogen preparation, the cellular localization and number of peroxidase-positive granules in the hypothalamus were determined in adult female rats treated with a single intramuscular injection of 2 mg of estradiol valerate. The persistent estrus state, manifested as persistent vaginal cornification and polycystic ovaries, was induced in 80% of the animals. In comparison with normally cycling controls, the arcuate nuclei of persistent estrus rats exhibited a 3- and 2.8-fold increase in numbers of diaminobenzidine-positive granules and granule clusters, respectively (P less than 0.01 for both comparisons). These peroxidase-positive granules were identified in astrocytes by double-label immunohistochemistry utilizing antiserum to glial fibrillary acidic protein. Diaminobenzidine staining occurred over a pH range of 4-10.5 and was resistant to the catalase inhibitor, aminotriazole, and to tissue pre-heating, indicating that the histochemical reaction was not due to tissue enzyme activity. Rather, these findings indicate that a non-enzymatic, pseudoperoxidation reaction has been induced in these cells by estrogen administration. Possible mediators of this reaction are metallo-porphyrins known to be present in rodent hypothalamus. The mechanisms by which astrocyte peroxidase activity may play a role in estrogen-related neural damage are discussed.

Animals↗
PubMed1989

Synergism between substrate and non-substrate thiols in peroxidase-oxidase reactions.

Cysteamine and reduced glutathione were shown to act synergistically as peroxidase-oxidase substrates as measured by oxygen consumption and Nitro Blue Tetrazolium reduction. Cysteine methyl ester could be substituted for cysteamine and N-acetylcysteine and penicillamine could be substituted for glutathione. The involvement of reduced oxygen species and the effects of pH and chloride were studied. A possible mechanism of peroxidase-oxidase oxidation of cysteamine and glutathione is proposed. These studies show that peroxidase oxidase reactions can occur with close to physiological concentrations of peroxidase and thiols.

Chromatography, High Pressure Liquid↗
PubMed1975

Acid proteinase and peroxidase activity in spielmeyer-Vogt's syndrome (Batten's syndrome-Stengel's syndrome).

The acid proteinase and the peroxidase activity of peripheral leucocytes of respectively 12 and 13 patients suffering from Spielmeyer-Vogt's disease, alias Batten's disease, alias Stengel's disease was studied. Cathepsin D activity was found to be normal in the disease, but the cathepsin B activity was decreased by 24 percent. However, the decrease was insignificant. The peroxidase assay was made using Guajacol as well as p-phenylenediamine as substrate. When the assay was performed with p-phenylenediamine, the enzymic activities were significantly decreased (p less than or equal to 1%) compared to the activity of normal control leucocytes. Assaying peroxidase activity by means of Guajacol revealed a non-significant difference between the two groups. The data obtained indicate the syndrome under study to be due to hampered peroxidase activity. The defect found explains the occurrence of lipofuchsin in the nervous system previously demonstrated.

Adolescent↗
PubMed1989

Stimulated intraphagosomal release of eosinophil peroxidase and acid phosphatase in the rats spontaneously infected with Mycoplasma pulmonis: a cytochemical study.

In this study we performed a cytochemical comparison of peroxidase and acid phosphatase activities in peritoneal eosinophils from specific pathogen-free (SPF) and Mycoplasma pulmonis-infected rats. When eosinophils ingested polystyrene particles for 120 min, peroxidase- and acid phosphatase-positive specific granules, as well as small granules, fused to phagosomes. Unusual peroxidase activity was detected in some particle-containing phagosomes in 6.8% of eosinophils from control SPF rats and 31% of those from infected rats. Intense acid phosphatase activity was also demonstrated in some phagosomes in 4 and 20% of eosinophils from control and infected rats, respectively. The rate of peroxidase-positive and acid phosphatase-positive phagosomes to all ingested phagosomes was 8.1 and 7.3% in control rats and rose to 41.3 and 31.1% in those infected, respectively. The population of eosinophils (18%) in the control peritoneal cells did not change after infection (16.6%). These results suggest that the intraphagosomal release of lysosomal enzymes was significantly stimulated in peritoneal eosinophils of the rats spontaneously infected with M. pulmonis.

Acid Phosphatase↗
PubMed1990

Oxidation of coniferyl alcohol by cell wall peroxidases at the expense of indole-3-acetic acid and O2. A model for the lignification of plant cell walls in the absence of H2O2.

The oxidation of coniferyl alcohol (CA), a lignin precursor, by cell wall peroxidases may take place at the expense of indole-3-acetic acid (IAA) and O2, and in the absence of H2O2. The peroxidase-catalyzed oxidation of CA shows an optimum at an IAA concentration of 0.33 mM, while higher IAA concentrations are inhibitory. The observation that the oxidation of CA by cell wall peroxidase at the expense of IAA and O2 is inhibited by genistein, a putative endogenous inhibitor of lignification in lupin hypocotyls, supports the view that the H2O2-generating system coexists with cell wall peroxidase activities involved in lignification, and that it takes place at the expense of IAA and O2.

Cell Wall↗
PubMed1993

Low pH crystal structure of glycosylated lignin peroxidase from Phanerochaete chrysosporium at 2.5 A resolution.

The heme-containing glycoprotein lignin peroxidase (pI 4.15) has been crystallized at pH 4.0. The structure of the peroxidase from the orthorhombic crystals has been determined by multiple isomorphous replacement. The model comprises all 343 amino acids, one heme molecule, and three sugar residues. It has been refined to an R-factor of 20.3%. The chain fold of residues 15 to 275 is in general similar to those of cytochrome c peroxidase. Despite binding of the heme to the same region and a similar arrangement of the proximal and distal histidine as in cytochrome c peroxidase a significantly larger distance of the iron ion to the proximal histidine is observed. Distinct electron density extending from Asn-257 and at the distal side of the heme indicates ordered sugar residues in the crystal.

Basidiomycota↗
PubMed1985

Increased erythrocyte glutathione peroxidase activity in psoriatics consuming high-selenium drinking water at the Dead-Sea Psoriasis Treatment Center.

Erythrocyte selenium-dependent glutathione peroxidase activity was measured in psoriatic Danes, before and after their four-week balneological therapy at the Ein-Bokek International Psoriasis Treatment Center, on the Dead-Sea shore in Israel. The drinking water in Ein-Bokek was found to be rich in selenium, a trace element with anticarcinogenic properties and of great importance in human nutrition and health. The most reliable biological parameter for increase in selenium bioavailability is the erythrocytes' glutathione-peroxidase activity. As psoriasis is a proliferative skin disease, the activity of this enzyme was assayed in 35 psoriatic Danes and in 25 long-term local hotel workers, as well as in 34 volunteers drinking low-selenium water. The glutathione peroxidase activity in the psoriatic patients increased significantly during their four-week stay in Ein-Bokek. Erythrocyte glutathione peroxidase activity in the hotel workers was 50% higher than that in the healthy volunteers consuming low-selenium water. A possible role of selenium in psoriasis is suggested.

Adult↗
PubMed1994

Superoxide dismutase, catalase, and glutathione peroxidase activities in muscle and lymphoid organs of sedentary and exercise-trained rats.

The effect of swimming-training upon the activities of the enzymes involved in the generation of reducing-equivalents (citrate synthase-mitochondria and glucose-6-phosphate dehydrogenase-cytosol) and of antioxidant enzymes (CuZn- and Mn-SOD, catalase and glutathione peroxidase) in the lymphoid organs (thymus, mesenteric lymph nodes and spleen) was examined. The skeletal muscles (soleus-red and gastrocnemius-white) were also studied. Although our data suggest an apparently random, organ-specific change in enzymatic activity, some interesting trends can be observed. Firstly, the increased citrate synthase and Mn-SOD activities observed in red, but not in white muscle, corroborate the well-known effect of endurance exercise-training on mitochondrial oxidative metabolism. Secondly, there was an inverse relationship between TBARs-monitored lipoperoxidation and glutathione peroxidase activity in all tissues studied, what is in accordance with the previous findings showing that such enzyme exerts the fine control of intracellular lipoperoxide concentration. Except in the case of the spleen, there was a trend for elevated glucose-6-phosphate dehydrogenase activity, coadjuvant of glutathione peroxidase in the antioxidant response to physical exercise in all tissues. Thirdly, Mn-SOD and catalase were conspicuously associated to oxidative stress in the thymus, while glutathione and catalase could be linked to this parameter in the spleen. Fourthly, the lymph nodes seem to be more dependent on the glucose-6-phosphate dehydrogenase/glutathione peroxidase pair for protection against damage promoted by physical exercise. Mn-SOD and catalase activities were lower in the lymph nodes after swimming training.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗