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PubMed1992

Comparison of extracellular peroxidase- and esterase-deficient mutants of Streptomyces viridosporus T7A.

Peroxidase-deficient mutants of the lignin-degrading bacterium Streptomyces viridosporus T7A were screened for their production of acid-precipitable polymeric lignin, extracellular peroxidases and esterases, and immunoreactivities against a polyclonal antibody produced against electrophoretically purified peroxidase isoform P3 of wild-type S. viridosporus. The mutants showed diminished abilities to solubilize lignin and produce acid-precipitable polymeric lignin. Their peroxidase activities were decreased, and their esterase production patterns were altered. Western immunoblots demonstrated that the mutants produced proteins immunologically reactive with the antibody, but with different mobilities from those of wild-type proteins. These findings confirm a direct role for peroxidases in lignin solubilization. They also indicate a possible role for esterases.

Esterases↗
PubMed1993

Ubiquity of lignin-degrading peroxidases among various wood-degrading fungi.

Phanerochaete chrysosporium is rapidly becoming a model system for the study of lignin biodegradation. Numerous studies on the physiology, biochemistry, chemistry, and genetics of this system have been performed. However, P. chrysosporium is not the only fungus to have a lignin-degrading enzyme system. Many other ligninolytic species of fungi, as well as other distantly related organisms which are known to produce lignin peroxidases, are described in this paper. In this study, we demonstrated the presence of the peroxidative enzymes in nine species not previously investigated. The fungi studied produced significant manganese peroxidase activity when they were grown on an oak sawdust substrate supplemented with wheat bran, millet, and sucrose. Many of the fungi also exhibited laccase and/or glyoxal oxidase activity. Inhibitors present in the medium prevented measurement of lignin peroxidase activity. However, Western blots (immunoblots) revealed that several of the fungi produced lignin peroxidase proteins. We concluded from this work that lignin-degrading peroxidases are present in nearly all ligninolytic fungi, but may be expressed differentially in different species. Substantial variability exists in the levels and types of ligninolytic enzymes produced by different white not fungi.

Alcohol Oxidoreductases↗
PubMed1999

Cloning and characterization of a cDNA encoding a novel extracellular peroxidase from Trametes versicolor.

The white rot basidiomycete Trametes versicolor secretes a large number of peroxidases which are believed to be involved in the degradation of polymeric lignin. These peroxidases have been classified previously as lignin peroxidases or manganese peroxidases (MnP). We have isolated a novel extracellular peroxidase-encoding cDNA sequence from T. versicolor CU1, the transcript levels of which are repressed by low concentrations of Mn2+ and induced by nitrogen and carbon but not induced in response to a range of stresses which have been reported to induce MnP expression.

Amino Acid Sequence↗
PubMed2000

Cloning, expression, and characterization of the katG gene, encoding catalase-peroxidase, from the polycyclic aromatic hydrocarbon-degrading bacterium Mycobacterium sp. strain PYR-1.

A 81-kDa protein from Mycobacterium sp. strain PYR-1 was expressed in response to exposure of the strain to the polycyclic aromatic hydrocarbon pyrene and recovered by two-dimensional gel electrophoresis. The N-terminal sequence of the protein indicated that it was similar to catalase-peroxidase. An oligonucleotide probe designed from this sequence was used to screen a genomic library of Mycobacterium sp. strain PYR-1, and a positive clone, containing a part of the gene encoding the 81-kDa protein, was isolated. A gene-walking technique was used to sequence the entire gene, which was identified as katG for catalase-peroxidase. The deduced KatG protein sequence showed significant homology to KatGII of Mycobacterium fortuitum and clustered with catalase-peroxidase proteins from other Mycobacterium species in a phylogenetic tree. The katG gene was expressed in Escherichia coli to produce a protein with catalase-peroxidase activity. Since the induction of this catalase-peroxidase occurred in pyrene-induced cultures and the exposure of these cultures to hydrogen peroxide reduced pyrene metabolism, our data suggest that this enzyme plays a role in polycyclic aromatic hydrocarbon metabolism by strain PYR-1.

Bacterial Proteins↗
PubMed2000

Studies on the production of fungal peroxidases in Aspergillus niger.

To get insight into the limiting factors existing for the efficient production of fungal peroxidase in filamentous fungi, the expression of the Phanerochaete chrysosporium lignin peroxidase H8 (lipA) and manganese peroxidase (MnP) H4 (mnp1) genes in Aspergillus niger has been studied. For this purpose, a protease-deficient A. niger strain and different expression cassettes have been used. Northern blotting experiments indicated high steady-state mRNA levels for the recombinant genes. Manganese peroxidase was secreted into the culture medium as an active protein. The recombinant protein showed specific activity and a spectrum profile similar to those of the native enzyme, was correctly processed at its N terminus, and had a slightly lower mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Recombinant MnP production could be increased up to 100 mg/liter upon hemoglobin supplementation of the culture medium. Lignin peroxidase was also secreted into the extracellular medium, although the protein was not active, presumably due to incorrect processing of the secreted enzyme. Expression of the lipA and mnp1 genes fused to the A. niger glucoamylase gene did not result in improved production yields.

Aspergillus niger↗
PubMed2002

Calnexin overexpression increases manganese peroxidase production in Aspergillus niger.

Heme-containing peroxidases from white rot basidiomycetes, in contrast to most proteins of fungal origin, are poorly produced in industrial filamentous fungal strains. Factors limiting peroxidase production are believed to operate at the posttranslational level. In particular, insufficient availability of the prosthetic group which is required for peroxidase biosynthesis has been proposed to be an important bottleneck. In this work, we analyzed the role of two components of the secretion pathway, the chaperones calnexin and binding protein (BiP), in the production of a fungal peroxidase. Expression of the Phanerochaete chrysosporium manganese peroxidase (MnP) in Aspergillus niger resulted in an increase in the expression level of the clxA and bipA genes. In a heme-supplemented medium, where MnP was shown to be overproduced to higher levels, induction of clxA and bipA was also higher. Overexpression of these two chaperones in an MnP-producing strain was analyzed for its effect on MnP production. Whereas bipA overexpression seriously reduced MnP production, overexpression of calnexin resulted in a four- to fivefold increase in the extracellular MnP levels. However, when additional heme was provided in the culture medium, calnexin overexpression had no synergistic effect on MnP production. The possible function of these two chaperones in MnP maturation and production is discussed.

Aspergillus niger↗
PubMed1993

Purification of a catalase-peroxidase from Halobacterium halobium: characterization of some unique properties of the halophilic enzyme.

A hydroperoxidase purified from the halophilic archaeon Halobacterium halobium exhibited both catalase and peroxidase activities, which were greatly diminished in a low-salt environment. Therefore, the purification was carried out in 2 M NaCl. Purified protein exhibited catalase activity over the narrow pH range of 6.0 to 7.5 and exhibited peroxidase activity between pH 6.5 and 8.0. Peroxidase activity was maximal at NaCl concentrations above 1 M, although catalase activity required 2 M NaCl for optimal function. Catalase activity was greatest at 50 degrees C; at 90 degrees C, the enzymatic activity was 20% greater than at 25 degrees C. Peroxidase activity decreased rapidly above its maximum at 40 degrees C. An activation energy of 2.5 kcal (ca. 10 kJ)/mol was calculated for catalase, and an activation energy of 4.0 kcal (ca. 17 kJ)/mol was calculated for peroxidase. Catalase activity was not inhibited by 3-amino-1,2,4-triazole but was inhibited by KCN and NaN3 (apparent Ki [KiApp] of 50 and 67.5 microM, respectively). Peroxidative activity was inhibited equally by KCN and NaN3 (KiApp for both, approximately 30 microM). The absorption spectrum showed a Soret peak at 404 nm, and there was no apparent reduction by dithionite. A heme content of 1.43 per tetramer was determined. The protein has a pI of 3.8 and an M(r) of 240,000 and consists of four subunits of 60,300 each.

Catalase↗
PubMed2006

Regulation of cytochrome C peroxidase activity by nitric oxide and laser irradiation.

Apoptosis can be induced by activation of so-called "death receptors" (extrinsic pathway) or multiple apoptotic factors (intrinsic pathway), which leads to release of cytochrome c from mitochondria. This event is considered to be a point of no return in apoptosis. One of the most important events in the development of apoptosis is the enhancement of cytochrome c peroxidase activity upon its interaction with cardiolipin, which modifies the active center of cytochrome c. In the present work, we have investigated the effects of nitric oxide on the cytochrome c peroxidase activity when cytochrome c is bound to cardiolipin or sodium dodecyl sulfate. We have observed that cytochrome c peroxidase activity, distinctly increased due to the presence of anionic lipids, is completely suppressed by nitric oxide. At the same time, nitrosyl complexes of cytochrome c, produced in the interaction with nitric oxide, demonstrated sensitivity to laser irradiation (441 nm) and were photolyzed during irradiation. This decomposition led to partial restoration of cytochrome c peroxidase activity. Finally, we conclude that nitric oxide and laser irradiation may serve as effective instruments for regulating the peroxidase activity of cytochrome c, and, probably, apoptosis.

Animals↗
PubMed1980

Characterization of leptospiral catalase and peroxidase.

Peroxidase from Leptospira biflexa strain B-16 ad catalase from Leptospira interrogans canicola Hond Utrecht were characterized and compared and both appeared to be heme enzymes as judged by their inhibition profiles and rapid inactivation during catalysis. Neither enzyme exhibited monovalent or divalent cation requirements. Dialysis of cell-free extracts resulted in loss of peroxidase activity but catalase was unaffected by this procedure. Peroxidase had a Km for H2O2 of 12.5 microM while catalase had a Km of 70 mM for H2O2. Catalase and peroxidase were physically separated by sedimentation in linear sucrose gradients. The specific activities of each enzyme seemed to be a function of the state of growth at which the cells were harvested and both enzymes were found associated with membranes, peroxidase by hydrophobic and catalase by ionic interactions. Speculative deductions are presented concerning the phylogenetic interrelationships of both enzymes as well as their significance in the biology and pathogenicity of leptospires.

Catalase↗
PubMed1983

Estrogen-androgen interaction: selective inhibition of estrogen-induced uterine peroxidase by testosterone and 5 alpha-dihydrotestosterone.

The effect of testosterone (T) and dihydrotestosterone (DHT) on the induction of peroxidase and glucose-6-phosphate dehydrogenase (G6PDH) in the immature rat uterus by estradiol (E2) was investigated. T (0.5-12.5 mg/rat) given on 3 successive days produced a large increase in uterine weight but, in contrast to E2, did not induce peroxidase or significantly augment uterine G6PDH. However, this androgen, even at a very low dose (50 micrograms/rat three times), inhibited the induction of peroxidase without a corresponding effect on G6PDH when given concurrently with E2 and was more effective than DHT. Inhibition by androgen was also observed when diethylstilbestrol was used to stimulate uterine growth. Combined treatment with E2 (3 micrograms/rat) and T (3 mg/rat) produced a cytosolic and nuclear estrogen receptor pattern in the uterus similar to that observed with E2 alone after various time intervals. The results speak against a direct inhibitory action or T on E2-induced uterine peroxidase via the estrogen receptor and confirm the lack of aromatization of T to E2 in the immature rat. Possible mechanisms for modifying the action of estrogens by androgens are discussed, particularly in the light of E2-induced eosinophilia. It is proposed that steroid hormones can interact in several ways and that uterine peroxidase provides a useful indicator to study steroid hormone action.

Animals↗
PubMed1999

Influence of glutathione peroxidase on coronary artery responses to alterations in PO2 and H2O2.

Our previous work suggests that relaxation of endothelium-removed bovine coronary arteries (BCA) to posthypoxic reoxygenation is mediated by NADH oxidase-dependent superoxide anion-derived H2O2 and cGMP. The purpose of this study was to investigate if altering BCA GSH peroxidase activity by enhancing its activity with a GSH peroxidase-mimetic (0.1 mM Ebselen) or by inhibiting its activity with an inhibitor of GSH peroxidase [10 mM mercaptosuccinic acid (MS)] causes a selective modulation of responses to exogenously (1 microM-1 mM H2O2) and endogenously generated (reoxygenation and 1-10 mM lactate) H2O2. Ebselen inhibited and MS enhanced all of the responses that are thought to be mediated by H2O2, without having significant effects on relaxation to hypoxia or a nitric oxide donor [1 nM-10 microM S-nitroso-N-acetylpenicillamine (SNAP)]. Thus enhancement of BCA GSH peroxidase activity with Ebselen inhibits relaxation to reoxygenation, lactate, and H2O2, whereas inhibition of GSH peroxidase with MS causes potentiation of responses thought to be mediated by H2O2 in BCA. Inactivation of catalase by pretreatment of BCA with 3-amino-1,2,4-triazole (50 mM, 30 min) inhibited relaxation to H2O2 and the potentiation by MS. Whereas the actions of these probes are not consistent with a role for oxidation of GSH in the relaxation to H2O2, their effects are potentially a result of modulating the metabolism of H2O2 by endogenous catalase, which is thought to mediate the stimulation of the cytosolic or soluble form of guanylate cyclase.

Animals↗
PubMed1992

Expression of peroxidase activity in rat tracheal epithelial cells associated with Mycoplasma pulmonis.

Endogenous peroxidase activity has not been localized in the tracheal mucosal epithelial cells of specific pathogen-free (SPF) rats. After natural infection with Mycoplasma pulmonis in SPF rats, peroxidase activity became localized to the endoplasmic reticulum, nuclear envelope, and Golgi apparatus of tracheal ciliated or mucous secretory cells. Some secretory cells occasionally had peroxidase-positive secretory granules. At 1 wk M. pulmonis was found to attach to these epithelial cells, which then showed positive peroxidase activity at 2 wk. Serum antibody titers against M. pulmonis were positive at 5 wk. These results suggest that virulent mycoplasma infection and interaction with the tracheal epithelial cells trigger the de novo expression of peroxidase activity, which seems to play a role in mucosal anti-microbial defense mechanisms.

Animals↗
PubMedDate not supplied

Effect of oral contraceptives on lacrimal fluid peroxidase activity in women.

Lacrimal fluid peroxidase has been supposed to be involved in the protection against oxidative damage to the ocular surface. Our recent findings showed the existence of significant cyclic variations in lacrimal fluid peroxidase activity that were positively correlated with those of 17beta-estradiol plasma levels throughout the menstrual cycle of fertile women. In the present study lacrimal fluid peroxidase activity of 8 healthy normocyclic women using low-dose oral contraceptives during the monthly cycle was determined. Data showed that low-dose oral contraceptives caused a decrease in lacrimal fluid peroxidase activity and a lack of its cyclic pattern with respect to the enzyme activity of 8 untreated age-matched women. Moreover, this result suggests that lacrimal fluid peroxidase activity could be regulated by estrogen.

Adult↗
PubMed2002

Peroxidase-mediated mechanisms are involved in the melanocytotoxic and melanogenesis-inhibiting effects of chemical agents.

Melanogenesis is based on the enzymatic conversion of the amino acid tyrosine, through a series of intermediates, to melanin pigments. The nature of the enzymes involved in the different steps of melanogenesis has been intensely debated. However, it is now believed that tyrosinase is responsible for the conversion of tyrosine to dopa and of dopa to dopaquinone, and that peroxidase accomplishes the oxidative polymerization of the eventually formed indoles to eumelanin pigments. Some very few investigators have also considered a main role for peroxidase in initiating melanogenesis. At present, most different hypotheses are focused on tyrosinase-mediated mechanisms to elucidate the melanocytotoxic and depigmenting activities of chemicals. However, many properties of these agents cannot be explained by such mechanisms. Most of the melanocytotoxic agents (e.g. hydroquinone, catechols, butylated hydroxyanisole) can be converted to cytotoxic species, such as quinones, by the peroxidase-H(2)O(2) system. On the other hand, many of the melanogenesis inhibitors which are not known to inhibit tyrosinase (e.g. glucocorticoids, ascorbic acid, indomethacin) have the capacity to strongly inhibit peroxidase activity. We have proposed that peroxidase-mediated mechanisms, in addition to or in several instances rather than tyrosinase-mediated mechanisms, can explain the melanocytotoxic and depigmenting properties of such agents.

Animals↗
PubMed1995

Paradoxical actions of antioxidants in the oxidation of low density lipoprotein by peroxidases.

Oxidation of LDL by peroxidases has been suggested to be a model for in vivo oxidation. The mechanism might involve the generation of an intermediate radical such as a phenoxy radical. We show that, in contrast to the oxidation of LDL by copper, oxidation by peroxidase system (H2O2/horse radish peroxidase) showed less resistance. This suggested that either the antioxidants were consumed more rapidly or might have actually participated in the oxidation. Accordingly, addition of vitamin E increased the rate of oxidation of LDL. In contrast, probucol inhibited the oxidation even at low concentrations suggesting ineffective formation of probucol radical or the sterically hindered probucol radical was inefficient in catalyzing subsequent oxidation. The oxidation of LDL by horse radish peroxidase was also enhanced in the presence of diphenylphenylenediamine, an antioxidant that does not have a phenolic -OH group. Myeloperoxidase was able to oxidize LDL even in the absence of added tyrosine suggesting that it was able to utilize the LDL-associated vitamin E. Addition of free tyrosine inhibited the formation of conjugated dienes. We suggest that if peroxidases are involved in the initiation of LDL oxidation in vivo, higher concentrations of antioxidants may be indicated to inhibit propagation of oxidation.

Antioxidants↗
PubMed1999

'Pseudohypouricosuria' in alcaptonuria: homogentisic acid interference in the measurement of urinary uric acid with the uricase-peroxidase reaction.

Urinary excretion of uric acid was found to be extremely low in a 58-year-old female patient with alcaptonuria. This was due to interference with the uricase-peroxidase method used, because analysis using high-performance liquid chromatography (HPLC) showed a normal urinary concentration of uric acid. In vitro experiments demonstrated that a high concentration of homogentisic acid in the patient's urine inhibited the peroxidase reaction, possibly due to inhibition of the colour development of 3-methyl-N-ethyl-N-(beta-hydroxyethyl)aniline (MEHA) and 4-aminoantipyrine, via the peroxidase reaction. A homogentisic acid concentration equivalent to that in plasma did not affect the uricase-peroxidase reaction. This result suggests that any assay based on a peroxidase method is affected by a high urinary concentration of homogentisic acid in patients with alcaptonuria.

Alkaptonuria↗
PubMed1999

Cumulative correlations of lysozyme, lactoferrin, peroxidase, S-IgA, amylase, and total protein concentrations with adherence of oral viridans streptococci to microplates coated with human saliva.

Redundancy refers to the observation that many salivary proteins exhibit similar properties in vitro. It is possible that bacterial adherence to salivary pellicle occurs as a cumulative effect of multiple proteins. This study determined the joint and individual contributions of salivary amylase, S-IgA, lysozyme, salivary peroxidase, lactoferrin, and total protein concentrations to adherence by oral viridans streptococci in microplates coated with whole saliva from 123 persons. Strains used were: Streptococcus gordonii Blackburn, 10558, Streptococcus mitis 10712, 903, Streptococcus oralis 10557, 9811, and Streptococcus sanguis 10556, 13379. Rabbit antibody against 13379 was used for the detection of adherence. This antibody cross-reacted with all strains. Absorbance was standardized against saliva pooled from five donors. All saliva samples had been previously assayed for amylase, lactoferrin, lysozyme, secretory IgA, peroxidase, and total protein. Adherence scores for all strains except 13379 were significantly and positively correlated. Salivas binding high or low levels of one strain tended to bind others correspondingly. Multiple regression indicated significant contributions to 10558 adherence from total protein and lactoferrin (positive), and peroxidase and lysozyme (negative). Similar results were obtained for Blackburn and 903. Significant individual correlations were seen for 9811 and total protein (positive), 10557 and peroxidase (negative), and 13379 and lactoferrin (negative). Salivas with high adherence scores contained significantly more protein and lactoferrin, and significantly less peroxidase, than salivas with low adherence scores. These findings support the hypothesis that multiple proteins contribute to the adherence of streptococcal strains in vivo.

Amylases↗
PubMed1976

A new method for the cytochemical demonstration of peroxidase for light, fluorescence and electron microscopy.

A new technique for the cytochemical demonstration of peroxidase is presented. Monomeric homovanillic acid is converted by H2O2 and peroxidase into its dimeric form, which is then precipitated as a complex salt of lead and rhodamine 6G or rhodamine B. The reaction product can be visualized by conversion to lead sulphide or viewed directly under the fluorescence microscope, since it emits a red fluorescence when excited with green light. The reaction is rapid and results in good localization at the cytologic level of peroxidase activity in granulocytes. The technique can be applied for the ultrastructural localization of enzymatic activity, but in its present form it does not match the localization sharpness of the diaminobenzidine method. This fluorescent cytochemical technique will also detect horseradish peroxidase activity and may provide a usefull probe in peroxidase immunohistochemistry. The principle of complexing metal salts with fluorescent dyes may find a more general application in enzyme cytochemistry.

Animals↗