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PubMed1972

Mononuclear phagocytes (Kupffer cells) and endothelial cells. Identification of two functional cell types in rat liver sinusoids by endogenous peroxidase activity.

The fine structural characteristics and phagocytic properties of peroxidase-positive and peroxidase-negative cells in rat hepatic sinusoids were investigated. Cells with a positive peroxidase reaction in the endoplasmic reticulum and the nuclear envelope make up approximately 40% of cells in rat hepatic sinusoids and have abundant cytoplasm containing numerous granules and vacuoles, and occasional tubular, vermiform invaginations. After intravenous injection of colloidal carbon, the luminal plasma membrane of these cells shows continuous sticking of carbon, and there is evidence of avid phagocytosis of colloidal carbon particles. Peroxidase-positive cells are the only cells in hepatic sinusoids which phagocytize large (0.8 micro in diameter) latex particles. In contrast, the peroxidase-negative endothelial cells, which make up 48% of cells, have scanty perinuclear cytoplasm and organelles, and their long cytoplasmic extensions that form the lining of the hepatic sinusoids have fenestrations; these cells ingest small amounts of colloidal carbon, principally by micropinocytosis, exhibit no sticking of carbon particles to their plasma membranes, and do not ingest the larger (latex) particles. The so-called fat-storing cells are peroxidase negative and totally nonphagocytic. The peroxidase reaction thus distinguishes the typical mononuclear phagocytes or Kupffer cells of rat liver from the endothelial-lining cells.

Animals↗
PubMed1987

Leukocyte adhesion receptors are stored in peroxidase-negative granules of human neutrophils.

Previous studies have suggested that the leukocyte adhesion proteins Mac-1 and p150,95 are stored in a latent intracellular pool in neutrophils, and cellular fractionation studies have shown that Mac-1 is localized primarily in the peroxidase-negative specific granules. To determine the subcellular location of leukocyte adhesion receptors (LAR), we used immunocytochemical techniques on frozen thin sections of human blood leukocytes that had been incubated for peroxidase to mark the peroxidase-positive azurophil granules. To enhance the sensitivity of detection, polyclonal antibodies against immunoaffinity-purified p150,95 were raised in rabbits and absorbed with leukocytes from a patient deficient in this protein. The antiserum reacted with p150,95 and two other antigens with the same beta subunit, Mac-1 and lymphocyte function-associated antigen 1 (LFA-1). In neutrophils, we observed immunogold label for LAR predominantly on the membranes of peroxidase-negative granules, and in smaller amounts on the plasma and perinuclear membranes. In double-label experiments, there was colocalization of LAR with lactoferrin in some of the peroxidase-negative granules. We conclude that the latent pool of LAR resides in the membranes of peroxidase-negative granules. A significant increase in label on the plasma membrane of neutrophils stimulated with PMA is consistent with secretion of LAR to the exterior of the cell during degranulation. While LFA-1 appears very early in neutrophil maturation, it is becoming clear that Mac-1 and p150,95 are upregulated from an intracellular storage pool of peroxidase-negative granules that appear during the myelocyte stage of differentiation. Further studies are indicated to determine the significance of these proteins on the plasma membrane of two other granulocytes, eosinophils and basophils.

Antigens, Surface↗
PubMed1985

Selenium repletion and glutathione peroxidase--differential effects on plasma and red blood cell enzyme activity.

We studied three children with chronic gastrointestinal disease who had been on intravenous hyperalimentation for periods of time ranging from 4 to 23 months. Each child was found to have low plasma and red blood cell glutathione peroxidase activity. This was associated, in the two children tested, with a marked deficiency of serum selenium. Their plasma glutathione peroxidase levels ranged between 4 and 24% of normal and their red blood cell levels ranged between 4 and 14% of normal. The intravenous alimentation was then supplemented with sodium selenite (240 micrograms Se/d). Within 4-5 weeks, the plasma glutathione peroxidase activity returned to normal. Red cell glutathione peroxidase activity remained essentially unchanged for 4-6 weeks, after which it increased over the following 3-4 months. Red cells were separated by density on a continuous Percoll-diatrizoate gradient. In normal individuals, the specific activity of glutathione peroxidase did not differ across the gradient despite a 2.5-fold difference in the specific activity of pyruvate kinase. When studied initially, glutathione peroxidase activity from the deficient patients did not change across the gradient. As the red cell enzyme activity increased with selenium repletion, the highest specific activity was initially found at the top of the gradient (youngest cells). After 3-4 months of supplementation, the specific activity became equal across the gradient. Thus, with selenium repletion, there is a rapid increase in plasma glutathione peroxidase activity, a 4-6 week lag prior to an increase in red cell enzyme activity, and the increase in red cell activity is due to newly synthesized red cells made in the presence of selenium.

Erythrocyte Aging↗
PubMed1980

Partial peroxidase deficiency in neutrophils and eosinophils associated with neurologic disease. Histochemical, cytochemical and biochemical studies.

Partial peroxidase deficiency was discovered by means of automated continuous-flow cytochemistry (Hemalog D) in the neutrophils and eosinophils of a patient admitted for evaluation of the gradual onset of intellectual deterioration. Wright's stain and routine benzidine peroxidase reaction on peripheral blood smears showed a normal differential count and peroxidase activity, respectively, but smears stained for peroxidase using 4-chloro-1-naphthol, the reagent used in Hemalog D, showed absence of enzymatic activity in neutrophils and eosinophils. Electron microscopy using the Graham-Karnovsky diamino-benzidine method confirmed these findings, demonstrating a new pattern of peroxidase deficiency in which a decreased number of peroxidase-positive granules were found in all neutrophils and, surprisingly, also in eosinophils. Bio-chemical studies also showed that the apparent deficiency is due to an abnormal proportion of "insoluble" peroxidase. These results and the clinical findings for the patient are consistent with the diagnosis of ceroid lipofuscinosis (Kuf's disease).

Bone Marrow↗
PubMed2004

An N-terminal peptide extension results in efficient expression, but not secretion, of a synthetic horseradish peroxidase gene in transgenic tobacco.

BACKGROUND AND AIMS: Native horseradish (Armoracia rusticana) peroxidase, HRP (EC 1.11.1.7), isoenzyme C is synthesized with N-terminal and C-terminal peptide extensions, believed to be associated with protein targeting. This study aimed to explore the specific functions of these extensions, and to generate transgenic plants with expression patterns suitable for exploring the role of peroxidase in plant development and defence. METHODS: Transgenic Nicotiana tabacum (tobacco) plants expressing different versions of a synthetic horseradish peroxidase, HRP, isoenzyme C gene were constructed. The gene was engineered to include additional sequences coding for either the natural N-terminal or the C-terminal extension or both. These constructs were placed under the control of a constitutive promoter (CaMV-35S) or the tobacco RUBISCO-SSU light inducible promoter (SSU) and introduced into tobacco using Agrobacterium-mediated transformation. To study the effects of the N- and C-terminal extensions, the localization of recombinant peroxidase was determined using biochemical and molecular techniques. KEY RESULTS: Transgenic tobacco plants can exhibit a ten-fold increase in peroxidase activity compared with wild-type tobacco levels, and the majority of this activity is located in the symplast. The N-terminal extension is essential for the production of high levels of recombinant protein, while the C-terminal extension has little effect. Differences in levels of enzyme activity and recombinant protein are reflected in transcript levels. CONCLUSIONS: There is no evidence to support either preferential secretion or vacuolar targeting of recombinant peroxidase in this heterologous expression system. This leads us to question the postulated targeting roles of these peptide extensions. The N-terminal extension is essential for high level expression and appears to influence transcript stability or translational efficiency. Plants have been generated with greatly elevated cytosolic peroxidase activity, and smaller increases in apoplastic activity. These will be valuable for exploring the role of these enzymes in stress amelioration and plant development.

Amino Acid Sequence↗
PubMed1992

Peroxidase-mediated glutathione conjugation of benzo[a]pyrene-7,8-dihydrodiol is enhanced by benzo[a]pyrene phenols in vitro.

We reported previously that glutathione (GSH) is oxidized by peroxidases to a thiyl radical that can react with a number of chemicals, including the penultimate carcinogenic metabolite benzo[a]pyrene-7,8-dihydrodiol (7,8-B[a]PD), to give GSH conjugates. Here, we report that phenolic metabolites of benzo[a]pyrene (B[a]P) enhance the peroxidase-mediated formation of glutathione conjugates of 7,8-B[a]PD. The GSH conjugation of 7,8-B[a]PD in a horseradish peroxidase/peroxide system was increased over control values as follows: 9-OH-B[a]P by 4-fold, 7-OH-B[a]P by 3-fold, 1-OH-B[a]P by 2-fold. In contrast 3-OH-B[a]P was ineffective. A phenolic derivative of another polycyclic aromatic hydrocarbon (PAH), benz[a]anthracene, also enhanced GSH conjugation of 7,8-B[a]PD. The enhancement was dependent upon the presence of the phenol, horseradish peroxidase and peroxide. The phenolic compounds, including 3-OH-B[a]P, were also efficient reducing cofactors for the peroxidase. With the exception of 3-OH-B[a]P, the phenolic metabolites of PAH enhanced peroxidase-mediated formation of thiyl radical as detected by electron spin resonance spectrometry. Since both phenols and dihydrodiols are metabolites of B[a]P catalyzed by the cytochromes P450 system, enhancement of peroxidase-dependent 7,8-B[a]PD-GSH conjugation by phenols suggests a possible interaction between peroxidases and cytochromes P450 systems. This interaction may contribute to the detoxication of the penultimate carcinogenic PAH-dihydrodiols and other chemicals.

Benzo(a)pyrene↗
PubMed1995

Peroxidase activation of tamoxifen and toremifene resulting in DNA damage and covalently bound protein adducts.

When [14C]tamoxifen was incubated with horseradish peroxidase and H2O2, two major metabolites, separated and identified by HPLC, were N-desmethyltamoxifen and tamoxifen N-oxide. Toremifene incubated in a similar system yielded N-desmethyltoremifene and toremifene N-oxide. No 4-hydroxylated metabolites were detected with either drug. When calf thymus DNA was included in peroxidase incubation mixtures, DNA damage, as assessed by 32P-postlabelling, could also be detected. The extent of damage caused by tamoxifen and toremifene was similar. The major adducts formed following incubation of DNA with tamoxifen had similar Rf values to two of the 32P-postlabelled adducts seen following dosing of rats with tamoxifen. Peroxidase was able to activate both drugs to derivatives which covalently bound to bovine serum albumin. The pH optimum for covalent binding and N-demethylation was near to pH 6.0. Results from liquid chromatography-electrospray secondary ion mass spectrometry suggest that tamoxifen and toremifene are metabolized by peroxidase to putative reactive epoxide intermediates responsible for the genotoxic effects. It is proposed that peroxidase oxidizes tamoxifen to a carbon-centred free radical which reacts with oxygen to form peroxy radicals capable of inserting an oxygen atom into tamoxifen. Lactoperoxidase and prostaglandin synthase are also able to catalyse tamoxifen N-demethylation and binding to protein. These data show that peroxidase can activate both tamoxifen and toremifene to an intermediate(s) that can damage DNA and covalently react with protein. Since it is known that women treated with tamoxifen can develop endometrial tumours, it may be relevant to determine whether activation of tamoxifen by peroxidases may contribute to its carcinogenic action at extrahepatic sites.

Animals↗
PubMed2006

Monolignol oxidation by xylem peroxidase isoforms of Norway spruce (Picea abies) and silver birch (Betula pendula).

We partially purified peroxidase isoform fractions from xylem extracts of a gymnosperm, Norway spruce (Picea abies (L.) Karst.), and an angiosperm, silver birch (Betula pendula Roth.), to determine the participation of xylem-localized peroxidases in polymerization of different types of lignin in vivo. Several peroxidase fractions varying in isoelectric point values from acidic to basic were tested for their ability to catalyze the oxidation of the monolignols coniferyl alcohol, sinapyl alcohol and p-coumaryl alcohol in vitro. All of the xylem peroxidases extracted from Norway spruce and most of those from silver birch showed the highest rate of oxidation with coniferyl alcohol in the presence of hydrogen peroxide. The exception was an acidic peroxidase fraction (pI 3.60-3.65) from silver birch that exhibited higher oxidation activity for sinapyl alcohol than for coniferyl alcohol. For the xylem enzyme fractions extracted from silver birch, the ability to oxidize the artificial phenolic substrate syringaldazine coincided with high specific activity for sinapyl alcohol. Therefore, we conclude that the acidic, neutral and basic xylem peroxidases of Norway spruce all function in the synthesis of guaiacyl-type lignin, whereas in silver birch the acidic peroxidases preferentially oxidize sinapyl subunits. The latter provides a mechanism for synthesis of guaiacyl-syringyl lignin typical of tracheid cell walls in angiosperm trees.

Betula↗
PubMed1992

Mechanisms of cytochrome P450 and peroxidase-catalyzed xenobiotic metabolism.

The cytochrome P450 enzyme systems catalyze the metabolism of a wide variety of naturally occurring and foreign compounds by reactions requiring NADPH and O2. Cytochrome P450 also catalyzes peroxide-dependent hydroxylation of substrates in the absence of NADPH and O2. Peroxidases such as chloroperoxidase and horseradish peroxidase catalyze peroxide-dependent reactions similar to those catalyzed by cytochrome P450. The kinetic and chemical mechanisms of the NADPH and O2-supported dealkylation reactions catalyzed by P450 have been investigated and compared with those catalyzed by P450 and peroxidases when the reactions are supported by peroxides. Detailed kinetic studies demonstrated that chloroperoxidase- and horseradish peroxidase-catalyzed N-demethylations proceed by a Ping Pong Bi Bi mechanism whereas P450-catalyzed O-dealkylations proceed by sequential mechanisms. Intramolecular isotope effect studies demonstrated that N-demethylations catalyzed by P450s and peroxidases proceed by different mechanisms. Most hemeproteins investigated catalyzed these reactions via abstraction of an alpha-carbon hydrogen whereas reactions catalyzed by P-450 and chloroperoxidase proceeded via an initial one-electron oxidation followed by alpha-carbon deprotonation. 18O-Labeling studies of the metabolism of NMC also demonstrated differences between the peroxidases and P450s. Because the hemeprotein prosthetic groups of P450, chloroperoxidase, and horseradish peroxidase are identical, the differences in the catalytic mechanisms result from differences in the environments provided by the proteins for the heme active site. It is suggested that the axial heme-iron thiolate moiety in P450 and chloroperoxidase may play a critical role in determining the mechanism of N-demethylation reactions catalyzed by these proteins.

Animals↗
PubMed1993

In situ localization of the secretion of lignin peroxidases in colonies of Phanerochaete chrysosporium using a sandwiched mode of culture.

Protein secretion and growth were investigated in Phanerochaete chrysosporium by using cultures sandwiched between perforated polycarbonate membranes. Labelling of colonies with radioactive N-acetylglucosamine and L-methionine indicated a close correlation between growth and general protein secretion, even in a central area of the colony secreting the idiophase enzymes lignin peroxidase (LiP) and manganese-dependent lignin peroxidase (MnP). Comparison of the sites of release into the medium of newly synthesized proteins and immuno-detected lignin peroxidases suggested that diffusion of the enzymes from the walls was a limiting step in the release of peroxidases into the medium. Microautoradiography of colonies exposed to N-acetyl[3H]glucosamine revealed the apical growth of thin hyphae and branches (4 to 5 microns diameter on average) in the central secreting area. These secondary hyphae showed peroxidase activity and reacted with lignin peroxidase antibodies. Although it was not possible to directly visualize secretion at hyphal tips, the results suggest that peroxidases (LiP and MnP) are initially secreted at the apex of secondary growing hyphae and later slowly released into the surrounding medium.

Fungi↗
PubMed2005

Two glutathione peroxidases in the fungal pathogen Cryptococcus neoformans are expressed in the presence of specific substrates.

Glutathione peroxidases catalyse the reduction of peroxides by reduced glutathione. To determine if these enzymes are important for resistance to oxidative stress and evasion of the innate immune system by the fungal pathogen Cryptococcus neoformans, two glutathione peroxidase homologues, which share 38 % identity, were identified and investigated. In this study, these peroxidases, Gpx1 and Gpx2, their localization, their contribution to total glutathione peroxidase activity, and their importance to the oxidative and nitrosative stress resistance of C. neoformans are described. It is shown that the two glutathione peroxidase genes are differentially expressed in response to stress. While both GPX1 and GPX2 are induced during t-butylhydroperoxide or cumene hydroperoxide stress and repressed during nitric oxide stress, only GPX2 is induced in response to hydrogen peroxide stress. Deletion mutants of each and both of the glutathione peroxidases were generated, and it was found that they are sensitive to various peroxide stresses while showing wild-type resistance to other oxidant stresses, such as superoxide and nitric oxide. While the glutathione peroxidase mutants are slightly sensitive to oxidant killing by macrophages, they exhibit wild-type virulence in a mouse model of cryptococcosis.

Animals↗
PubMed1997

Purification and characterization of a novel class III peroxidase isoenzyme from tea leaves.

A novel, basic (isoelectric point > 10), heme peroxidase isoenzyme (TP; relative molecular weight = 34,660 +/- 10, mean +/- SE) that can account for a significant part of the ascorbate peroxidase activity in tea (Camellia sinensis) leaves has been purified to homogeneity. The ultraviolet/visible absorption spectrum is typical of heme-containing plant peroxidases, with a Soret peak at 406 nm (epsilon = 115 mM-1 cm-1) and an A406/A280 value of 3.4. The enzyme has a high specific activity for ascorbate oxidation (151 mumol min-1 mg-1), with a pH optimum in the range of 4.5 to 5.0. Substrate-specificity studies have revealed significant differences between TP and other class III peroxidases, as well as similarities with class I ascorbate peroxidases. TP, like ascorbate peroxidase, exhibits a preference for ascorbate over guaiacol, whereas other class III isoenzymes are characterized by 2-orders-of-magnitude higher activity for guaiacol than for ascorbate. TP also forms an unstable porphyrin pi cation radical-type compound I, which is converted to compound II within approximately 2 min in the absence of added reductant. Amino acid sequence data show TP to be the first example, to our knowledge, of a class III peroxidase with a high specificity for ascorbate as an electron donor.

Chromatography, Gel↗
PubMed2000

A tomato peroxidase involved in the synthesis of lignin and suberin.

The last step in the synthesis of lignin and suberin has been proposed to be catalyzed by peroxidases, although other proteins may also be involved. To determine which peroxidases are involved in the synthesis of lignin and suberin, five peroxidases from tomato (Lycopersicon esculentum) roots, representing the majority of the peroxidase activity in this organ, have been partially purified and characterized kinetically. The purified peroxidases with isoelectric point (pI) values of 3.6 and 9.6 showed the highest catalytic efficiency when the substrate used was syringaldazine, an analog of lignin monomer. Using a combination of transgenic expression and antibody recognition, we now show that the peroxidase pI 9.6 is probably encoded by TPX1, a tomato peroxidase gene we have previously isolated. In situ RNA hybridization revealed that TPX1 expression is restricted to cells undergoing synthesis of lignin and suberin. Salt stress has been reported to induce the synthesis of lignin and/or suberin. This stress applied to tomato caused changes in the expression pattern of TPX1 and induced the TPX1 protein. We propose that the TPX1 product is involved in the synthesis of lignin and suberin.

Kinetics↗
PubMed1967

Peroxidase associated with higher plant mitochondria.

The presence of peroxidase in mitochondria from etiolated mung bean hypocotyls and skunk cabbage spadices, suggested by carbon monoxide difference spectra and the spectral response to methyl hydroperoxide, was shown to result from contamination of the isolated mitochondria by a denser particle fraction with high peroxidase activity. The mitochondria themselves have no peroxidatic activity. Analysis of the homogenate of mung bean hypocotyls revealed that over 90% of the peroxidase was soluble, as expected. Sonication of the isolated mitochondria, however, did not remove all the peroxidase from the particulate fraction, indicating that some of this enzyme is tightly bound to a membrane. These results suggest that the peroxidase in plant cells is localized in lysosomes or microbodies, most of which are ruptured on tissue homogenization to give soluble peroxidase, but some of which survive and appear as membrane bound peroxidase.

Lysosomes↗
PubMed1988

Production and characterization of monoclonal antibodies to wall-localized peroxidases from corn seedlings.

A library of 22 hybridomas, which make antibodies to soluble wall antigens from the coleoptiles and primary leaves of etiolated corn (Zea mays L.) seedlings, was raised and cloned three times by limit dilution to assure monoclonal growth and stability. Two of these hybridomas made immunoglobulin G antibodies, designated mWP3 and mWP19, which both effectively immunoprecipitated peroxidase activity from crude and partially purified preparations of wall peroxidases. Direct peroxidase-binding assays revealed that both antibodies bound enzymes with peroxidase activity. As judged by immunoblot analyses, mWP3 recognized a Mr 98,000 wall peroxidase with an isoelectric point near 4.2, and mWP19 recognized a Mr 58,000 wall peroxidase. Immunogold localization studies showed both peroxidases are predominately in cell walls.

Antibodies, Monoclonal↗
PubMed1994

Peroxidase-positive round cells and microorganisms in human semen together with antibiotic treatment adversely influence the outcome of in-vitro fertilization and embryo transfer.

Human semen contains not only spermatozoa but also other cells routinely differentiated as being peroxidase-positive (e.g. leucocytes) and peroxidase-negative (e.g. immature germ cells and lymphocytes) cells. Considerable uncertainty exists about their role in male fertility. To assess the clinical value of both parameters, and of microorganisms in semen, 391 treatments with in-vitro fertilization and embryo transfer were analysed retrospectively, and the concentrations of both peroxidase-positive and -negative cells, together with the presence of microorganisms in semen, were compared with both the fertilization and pregnancy rates. The data indicate that the results of treatment were affected only by excessively elevated concentrations of peroxidase-positive cells (> 6 x 10(6)/ml) and only marginally by the presence of microorganisms in the semen. The pregnancy rate after in-vitro fertilization and embryo transfer was not improved by antibiotic treatments preceding gamete recovery by several weeks. The increased presence of peroxidase-negative cells (e.g. germ cells) in semen was not associated with a significant change in the pregnancy rate. However, the concentration of peroxidase-negative cells in semen correlated significantly with sperm numbers (p < 0.01), sperm concentration (p < 0.01), and normal morphology rates (p < 0.01). It is concluded that short-term antibiotic treatment of asymptomatic patients before assisted reproduction should be handled with caution. The widespread view that peroxidase-negative cells in semen are harmful is rejected.

Anti-Bacterial Agents↗
PubMed1975

Free diiodotyrosine effects on protein iodination and thyroid hormone synthesis catalyzed by thyroid peroxidase.

Free diiosotyrosine exerts two opposite effects on the reactions catalyzed by thyroid peroxidase, thyroglobulin iodination and thyroid hormone formation. 1. Inhibition of thyroglobulin iodination catalyzed by thyroid peroxidase was observed when free diiodotyrosine concentration was higher than 5 muM. This inhibition was competitive, suggesting that free diiodotyrosine interacts with the substrate site(s) of thyroid peroxidase. Free diiodotyrosine also competively inhibited iodide peroxidation to I2. 2. Free diiodotyrosine, when incubated with thyroid peroxidase in the absence of iodide was recovered unmodified; in the presence of iodide an exchange reaction was observed between the iodine atoms present in the diiodotyrosine molecule and iodide present in the medium. Using 14C-labelled diiodotyrosine, 14C-labelled non-iodinated products were also observed, showing that deiodination occurred as a minor degradation pathway. However, no monoiodo[14C]tyrosine or E114C]tyrosine were observed. Exchange reaction between free diiototyrosine and iodide is therefore direct and does not imply deiodination-iodination intermediary steps. Thyroglobulin inhibits diiodotyrosine-iodide exchange and vice versa, again suggesting competition for both reactions. These results support, by a different experimental approach, the two-site model for peroxidase previously described by us in this journal. 3. Free diiodotyrosine when present at a very low concentration, 0.05 muM, exerts a stimulatory effect on throid hormones synthesis. The relationship between diiodotyrosine concentration and thyroid hormone synthesis give an S-shaped curve, suggesting that free diiodotyrosine acts as a regulatory ligand for thyroid peroxidase. Evidence is also presented that free diiodotyrosine is not incorporated into thyroid hormones. Therefore, thyroid peroxidase catalyzes only intra-molecular coupling between iodotyrosine hormonogenic residues. 4. Finally, although no direct proof exists that these free diiodotyrosine effects upon thyroglobulin iodination and thyroid hormone synthesis are physiologically significant, such a possibility deserves further investigation.

Animals↗
PubMed1979

The peroxidase activity of rat uterus.

The peroxidase activity in the uterine extract of rats previously given a low dose of oestradiol has been examined. From sexually mature rats, two peroxidases of apparent molecular weights of 92 000 (peroxidase I) and 40 000 (peroxidase II) and of different mobilities in polyacrylamide disc gel electrophoresis were found. The two peroxidases were separated and characterized in terms of their substrate specificities, kinetics, pH optima for activity, inhibitors and stabilities. Both enzymes appeared to be classic haemoprotein peroxidases of very similar properties. Peroxidase II was further purified.

Animals↗