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PubMed2004

Topographic and age-dependent expression of heme oxygenase-1 and catalase in the human retinal pigment epithelium.

PURPOSE: To investigate the hypothesis that there are topographic and age-related changes in the expression of heme oxygenase (HO)-1 and catalase in the RPE. METHODS: Cryosections of the macula and periphery of human eyes (n = 18; aged 27-87 years) were subjected to a high-sensitivity digoxigenin (DIG)-labeled cRNA in situ hybridization protocol to determine the expression of HO-1 and catalase. The immunoreactivity of HO-1 and catalase were also investigated in the same sample set. Specimens were examined by light microscopy, and images were captured with a digital camera. The total number of RPE cells and HO-1- and catalase-labeled RPE cells was counted in each section, and the ratio of labeled RPE cells to total RPE cells was calculated in both the macular and the peripheral regions of each donor eye. RESULTS: There was a mosaic pattern of mRNA and protein expression of HO-1 and catalase in macular and peripheral RPE. Topographical differences in the expression of HO-1 at the mRNA level and catalase at both the mRNA and protein levels was also observed. The topographical differences between the expression of HO-1 in the macula and periphery protein were not statistically significant but showed similar trends. For HO-1, the only significant age-related decline in expression was observed in the macula and periphery. Expression of HO-1 at the protein level and that of catalase at both the mRNA and protein levels showed no significant decline with age. CONCLUSIONS: There is a possible age-related decline in HO-1 expression, whereas catalase expression remains unchanged with aging. Both exhibit mosaic patterns in the RPE monolayer.

Adult↗
PubMed1992

Regulation of catalase in Neisseria gonorrhoeae. Effects of oxidant stress and exposure to human neutrophils.

We studied the effects of oxidant stress on the catalase activity and hydrogen peroxide sensitivity of Neisseria gonorrhoeae. N. gonorrhoeae is an obligate pathogen of man that evokes a remarkable but ineffective neutrophil response. Gonococci make no superoxide dismutase but express high catalase activity. Gonococcal catalase activity increased threefold when organisms were subjected to 1.0 mM hydrogen peroxide. This increase in catalase activity was marked by a parallel increase in protein concentration recognized by a rabbit polyclonal antibody raised against the purified gonococcal enzyme. Catalase was primarily localized to the gonococcal cytoplasm in the presence or absence of stress; only a single isoenzyme of catalase could be identified. Exposure of gonococci to neutrophil-derived oxidants was accomplished by stimulating neutrophils with phorbol myristate acetate or by using gonococcal Opa variants that interacted with neutrophils with different degrees of efficiency. Gonococci exposed to neutrophils demonstrated a twofold increase in catalase activity in spite of some reduction in viability. Exposure of gonococci to 1.0 mM hydrogen peroxide made the organisms significantly more resistant to higher concentrations of hydrogen peroxide and to neutrophils than control organisms. These results suggest that catalase is an important defense for N. gonorrhoeae during attack by human neutrophils. The rapid response of this enzyme to hydrogen peroxide should be taken into consideration in studies designed to evaluate the interaction between neutrophils and gonococci.

Catalase↗
PubMed2002

Identification of a functional peroxisome proliferator-activated receptor response element in the rat catalase promoter.

Peroxisomal proliferator-activated receptor (PPAR)gamma has been shown to decrease the inflammatory response via transrepression of proinflammatory transcription factors. However, the identity of PPARgamma responsive genes that decrease the inflammatory response has remained elusive. Because generation of the reactive oxygen species hydrogen peroxide (H(2)O(2)) plays a role in the inflammatory process and activation of proinflammatory transcription factors, we wanted to determine whether the antioxidant enzyme catalase might be a PPARgamma target gene. We identified a putative PPAR response element (PPRE) containing the canonical direct repeat 1 motif, AGGTGA-A-AGTTGA, in the rat catalase promoter. In vitro translated PPARgamma and retinoic X receptor-alpha proteins were able to bind to the catalase PPRE. Promoter deletion analysis revealed that the PPRE was functional, and a heterologous promoter construct containing a multimerized catalase PPRE demonstrated that the PPRE was necessary and sufficient for PPARgamma-mediated activation. Treatment of microvascular endothelial cells with PPARgamma ligands led to increases in catalase mRNA and activity. These results demonstrate that PPARgamma can alter catalase expression; this occurs via a PPRE in the rat catalase promoter. Thus, in addition to transrepression of proinflammatory transcription factors, PPARgamma may also be modulating catalase expression, and hence down-regulating the inflammatory response via scavenging of reactive oxygen species.

Animals↗
PubMed2001

Catalase contents in cells determine sensitivity to the apoptosis inducer gallic acid.

Gallic acid (3,4,5-trihydroxybenzoic acid, GA) is known to induce apoptosis in cancer cells at lower IC50 values compared with values for normal cells. Apoptosis is inhibited completely by the addition of conditioned medium from cultured hepatocytes, whereas it is not prevented by conditioned media from tumor cells. We therefore studied the reason for the different response to GA-induced apoposis. GA-induced dRLh-84 cell death was completely abolished by the addition of peroxisome or cytosol as well as conditioned medium from primary cultured rat hepatocyte. As GA-induced cell death is known to be mediated by reactive oxygen species (ROS) and intracellular Ca2+, we determined the type of ROS generated by GA and found that GA generated hydrogen peroxide in culture medium. The addition of hydrogen peroxide generated by GA induced cell death in dRLh-84 cells. These results suggest that GA-induced cell death is mediated by hydrogen peroxide. On the other hand, the inhibitory activity of hepatocyte medium on GA-induced cell death was completely abolished by anti-catalase antibody. When the amount of catalase antigen was determined by Western blotting analysis, conditioned medium and the cytoplasm of hepatocytes contained high concentrations of catalase. Conditioned media from various tumor cell lines did not contain catalase, and the cytoplasm contained only low levels of catalase. These results show that GA-sensitive cells, including various tumor cells, produce only small amounts of catalase and secreted little enzyme into media, suggesting a lack of protective machinery against GA. In contrast, GA-insensitive cells, including hepatocytes, produce large amounts of catalase and release it in medium, resulting in the development of insensitivity to GA. In conclusion, catalase contents in cells determine different sensitivity to GA.

Animals↗
PubMed1996

Construction of catalase deficient Escherichia coli strains for the production of uricase.

To produce catalase-free uricase preparations, we constructed catalase-deficient strains from Escherichai coli MC1000 and MM294 and used them as recombinant host strains. The parent strains and catalase-deficient strains showed no differences in the growth characteristics by shaking culture in Erlenmeyer flasks. The catalase deficient strain derived from MC1000 transformed with the uricase expression plasmid pUT118 (strain SN0037) had growth characteristics and the uricase productivity comparable to those of the parent host strain MC1000 in fed-batch culture in a jar fermentor and no catalase activity was detected in cell-free extracts. However, the katG disrupted strains from MM294 carrying pUT118 had poor growth and their uricase productivities were low compared to those of the parent strain MM294. Using the strain SN0037, a catalase-free uricase preparation was obtained with fewer purification procedures and the final recovery of uricase activity was improved. The catalase-deficient E. coli host strain will be a suitable host for the production of the uricase, free of catalase activity, in high yield.

Acatalasia↗
PubMed2004

Alkali- and halo-tolerant catalase from Halomonas sp. SK1: overexpression in Escherichia coli, purification, characterization, and genetic modification.

A catalase gene, ohktA, from an alkali- and halo-tolerant bacterium, Halomonas sp. SK1, on the pKK223-3, was expressed in the catalase-lacking Escherichia coli strain UM2. Highly purified catalase showing a single band on SDS-PAGE was obtained by two liquid chromatography steps on DEAE-Toyopear1 and Chelating-Sepharose Fast Flow. The enzyme, oHktA, shows high catalase activity with a pH optimum at 10, and the activity was stable in 4 M KC1. This enzyme is thermo-sensitive, showing a significant loss of activity within 5 minutes at 37 degrees C. To modify the stability of the catalase, the addition of domain II of the heat stable Mn catalase from Thermus thermophilus to the C-terminus was made. When coexpressed with a chaperone (PhFKBP29) gene product, peptidyl-prolyl cis-trans isomerase, from a thermophilic bacterium, a chimeric catalase was produced in the soluble fraction. The stability of this catalase in the range of 37 degrees -45 degrees C was improved and it was stable for more than 1 h at 37 degrees C.

Alkalies↗
PubMed2005

Catalase regulates cell growth in HL60 human promyelocytic cells: evidence for growth regulation by H(2)O(2).

Reactive oxygen species (ROS) including hydrogen peroxide (H(2)O(2)) are generated constitutively in mammalian cells. Because of its relatively long life and high permeability across membranes, H(2)O(2) is thought to be an important second messenger. Generation of H(2)O(2) is increased in response to external insults, including radiation. Catalase is located at the peroxisome and scavenges H(2)O(2). In this study, we investigated the role of catalase in cell growth using the H(2)O(2)-resistant variant HP100-1 of human promyelocytic HL60 cells. HP100-1 cells had an almost 10-fold higher activity of catalase than HL60 cells without differences in levels of glutathione peroxidase, manganese superoxide dismutase (MnSOD), and copper-zinc SOD (CuZnSOD). HP100-1 cells had higher proliferative activity than HL60 cells. Treatment with catalase or the introduction of catalase cDNA into HL60 cells stimulated cell growth. Exposure of HP100-1 cells to a catalase inhibitor resulted in suppression of cell growth with concomitant increased levels of intracellular H(2)O(2). Moreover, exogenously added H(2)O(2) or depletion of glutathione suppressed cell growth in HL60 cells. Extracellular signal regulated kinase 1/2 (ERK1/2) was constitutively phosphorylated in HP100-1 cells but not in HL60 cells. Inhibition of the ERK1/2 pathway suppressed the growth of HP100-1 cells, but inhibition of p38 mitogen-activated protein kinase (p38MAPK) did not affect growth. Moreover, inhibition of catalase blocked the phosphorylation of ERK1/2 but not of p38MAPK in HP100-1 cells. Thus our results suggest that catalase activates the growth of HL60 cells through dismutation of H(2)O(2), leading to activation of the ERK1/2 pathway; H(2)O(2) is an important regulator of growth in HL60 cells.

Antioxidants↗
PubMed2000

Catalase activity in equine semen.

OBJECTIVE: To characterize the activity of catalase in equine semen. ANIMALS: 15 stallions of known and unknown reproductive history. PROCEDURE: Seminal plasma was collected from raw equine semen by centrifugation, and samples of seminal plasma were frozen prior to assay for catalase activity. Tissue samples (n = 3 stallions) from the bulbourethral gland, prostate gland, vesicular gland, and testis were homogenized, and cauda epididymal fluid was collected for determination of catalase activity. Catalase activity was determined as an enzyme kinetic assay by the disappearance of H2O2 as measured by ultraviolet spectrophotometry. RESULTS: Catalase activity in equine seminal plasma was 989.3 +/- 1678 U/ml (mean +/- SEM), and the specific activity of catalase in equine seminal plasma was 98.7 +/- 29.2 U/mg of protein. Specific activity of catalase in tissue homogenates was significantly higher in the prostate gland (954 +/- 270 U/mg of protein) than in the ampulla (59 +/- 5 U/mg of protein), bulbourethral gland (54 +/- 11 U/mg of protein), vesicular gland (39 +/- 3 U/mg of protein), cauda epididymal fluid (11 +/- 3 U/mg protein), or testis (54 +/- 6 U/mg of protein). CONCLUSIONS AND CLINICAL RELEVANCE: Equine seminal plasma contains a high activity of catalase that is derived primarily from prostatic secretions. Procedures such as semen cryopreservation that remove most seminal plasma from semen may reduce the ability to scavenge H2O2 and thereby increase the susceptibility of spermatozoa to oxidative stress.

Amitrole↗
PubMed1987

Factor analysis of the activities of superoxide dismutase, catalase and glutathione peroxidase in normal tissues and neoplastic cell lines.

Exploratory factor analysis of reported specific activities of the antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase in normal human tissues, normal mouse tissues, vertebrate red blood cells and neoplastic human cell lines shows that the activities of copper-zinc superoxide dismutase, catalase and glutathione peroxidase in normal tissues are influenced by a single factor. Catalase activity has the highest loading and correlation with this factor, suggesting a catalase- or hydrogen peroxide-related influence. The activity of manganese superoxide dismutase is influenced by a separate factor. The activities of copper-zinc and manganese superoxide dismutases in normal tissues therefore appear to be dichotomously regulated. The activities of superoxide dismutase and glutathione peroxidase in vertebrate red blood cells are influenced by a single factor. The activity of catalase is influenced by a separate factor. The roles of glutathione peroxidase and catalase in hydrogen peroxide catabolism in red blood cells in fact differ. In neoplastic human cell lines, two bipolar factor factors appear to influence the activities of catalase and manganese superoxide dismutase, and glutathione peroxidase and copper-zinc superoxide dismutase, respectively. The factors are, however, mainly catalase and glutathione peroxidase activity factors as the loadings and correlations of manganese superoxide dismutase on the one hand and copper-zinc superoxide dismutase on the other, with the respective factors, are relatively small. Potentially low superoxide production and intrinsically low peroxidizability of tumour cell membranes underlie the peculiar variation of antioxidant enzyme activities in tumour cells. Factor analysis is proposed as a heuristic data reduction and hypothesis-creating technique for the variation of antioxidant and other functionally-linked enzyme activities in normal and pathological cells and tissues.

Analysis of Variance↗
PubMed1997

Effect of high concentration of ascorbate on catalase activity in cultured cells and tissues of guinea pigs.

This study showed that the inhibition of cell growth in 3T6, induced by the supplementation of ascorbate at 0.5 mM in cultured medium, was prevented by the addition of catalase in the range of 25-750 units/mL regardless of the degree of activity. However, cytotoxicity induced by concentrations of more than 2 mM ascorbate could not be prevented even when a high level of catalase (5,000 units/mL) was added to the medium. Catalase activity in medium supplemented with ascorbate decreased with incubation time; the higher the concentration of ascorbate, the greater the decrease in catalase activity. These results indicate that even though catalase is present at a high concentration in the medium, it cannot prevent cytotoxicity by a high concentration of ascorbate because the oxygen radical derived from ascorbate inhibits its activity. We therefore investigated whether the inhibition of catalase activity by ascorbate could be observed in animal tissues. The catalase activity in the tissues of guinea pigs 6h after the administration of ascorbate was lower than that in non-administered animals. When guinea pigs were fed diets containing 5 mg or 100 mg ascorbate/animal over a 90 weeks period, a clear affect on catalase activity in the high-dose ascorbate group as compared to that in the low-dose ascorbate group was not observed.

Animals↗
PubMed1997

Repression of hypoxia-reoxygenation injury in the catalase-overexpressing heart of transgenic mice.

Hypoxia-reoxygenation injury results at least in part from reactive oxygen free radicals. Catalase is a major enzyme involved in detoxification of hydrogen peroxide. The activity of catalase per gram of tissue in the heart is very low, being only about 2% that of liver in rodents and humans, which may be responsible for the high sensitivity of the heart to hypoxia-reoxygenation injury. The present study was undertaken to determine whether elevation of catalase specifically in the heart of transgenic mice could provide protection against hypoxia-reoxygenation injury. Transgenic mice with elevated cardiac catalase 60-fold higher than normal were selected, and the effects of catalase elevation on hypoxia-reoxygenation induced functional and morphological changes in isolated atria were determined. Catalase overexpression ameliorated reductions in contractile force and heart rate caused by hypoxia-reoxygenation, and eliminated reoxygenation-induced arrhythmia. The catalase-overexpressing transgenic atria were also highly resistant to hypoxia-reoxygenation-induced morphological alterations, as examined by electron microscopy. Use of cardiac catalase-overexpressing transgenic mice thus demonstrates that hydrogen peroxide is involved in hypoxia-reoxygenation cardiotoxicity, and that this mouse model provides a useful tool for study of free radical mechanism in the heart damage.

Animals↗
PubMed2005

The nucleotide sequence determination of catalases of three medically important yeasts using newly designed degenerated primers.

We have developed degenerated primers for the isolation of several fungal species catalases, based on the known catalase genes of several yeast species. Using a combination of degenerated primers and the nested polymerase chain reaction (PCR) method, we were able to obtain PCR products from Candida dubliniensis, C. tropicalis, and C. glabrata. The nucleotide sequence of the PCR products amplified showed that those fragments contained sequences homologous with the known Candida catalases, indicating the usefulness of the designed primers. We determined the nucleotide sequences of the open reading frames and respective 5' untranscribed regions of these yeasts and compared each sequence with that of the respective related species. The difference between the deduced amino acid sequence of catalase of C. dubliniensis and C. albicans was 5 in 485 amino acids. The nucleotide sequence of C. glabrata catalase was identical to the sequence results from the genome sequence project which was recently released, whereas that of the catalase of the C. tropicalis clinical isolate was not the same as the strain Pk233, n-alkane-utilizing C. tropicalis. The catalase activities of all the strains tested so far were activated by short-term hydrogen peroxide treatment, suggesting that common mechanisms were involved in the induction of catalase activity, although the nucleotide sequences of the 5' untranscribed region of these yeasts were diversified.

Base Sequence↗
PubMed2006

Catalases of Aspergillus fumigatus and inflammation in aspergillosis.

The article describes various features of aspergillosis and a discussed the role of calatases produced by Aspergillus fumigatus during infection. Since a large body of invasive Aspergillus infection occurs as an opportunistic infection in variously impaired defense mechanisms, there is a wide spectrum of histopathological features of lesions demonstrated at the site of infection. Accordingly, histopathology of the lesions can be understood as a phenotypical representation of interaction between differently impaired functions of neutrophils and macrophages and virulence factors of invading Aspergilli. Consideration of previous pathological knowledge regarding infection and inflammation provides much important information to predict the pathophysiology of a patient. Meanwhile, detoxification of hydrogen peroxide by catalases has been proposed as a way to overcome this host response. A. fumigatus produces three active catalases, one from conidia and two from mycelia. CatAp, a spore specific monofunctional catalase, is resistant to heat and metal ions. In spite of their increased sensitivity to H(2)O(2), killing of catA conidia by alveolar macrophages, virulence in animals was similar to wild type conidia. In contrast to mycelial Cat1p, and CatAp catalases, the mycelial Cat2p is a bifunctional catalase-peroxidase enzyme and is also sensitive to heat, metal ions and detergent. Surprisingly, the mycelium of the double cat1 cat2 mutant with no catalase activity has only a slightly increased sensitivity to H(2)O(2) and was as sensitive to the killing of polymorphonuclear neutrophils as the wild type strain. However, it showed a delayed infection in the rat model of aspergillosis compared to the wild type strain. Consequently, it should be emphasized that conidial catalase is not a virulence factor but that mycelial catalases transiently protect the fungus from the host defence reactions.

Aspergillosis↗
PubMed2000

Effect of gallic acid polydisulfide on activity and stability of catalase in various media.

The effect of the active bioantioxidant polydisulfide of gallic acid (PDSG) on the catalytic activity and operational and thermal stability of catalase was studied in three media: distilled water (pH approximately 5.6), phosphate buffer, pH 7.4, and reversed micelles of Aerosol OT (AOT) in heptane of varied hydration degree w0. PDSG inhibited the catalase-induced decomposition of H2O2 by the mixed or noncompetitive mechanism: in various media the inactivation constant Ki varied in the range of (0.63-2.32).10-5 M. PDSG nearly twofold decreased the rate constant of interaction of the complex I of catalase with H2O2 (k2, M-1.sec-1) in water and reversed micelles of AOT and 3-5 times increased the effective rate constant of catalase thermal inactivation, k*in, sec-1, depending on the reaction medium. PDSG significantly decreased the rate constant of catalase inactivation during the enzymatic reaction, kin, sec-1, and thus increased the enzyme operational stability in water and reversed AOT micelles in heptane. The interaction of PDSG with catalase in water and in phosphate buffer was accompanied by significant changes in CD spectra in the far UV-region that indicated disturbances in the secondary structure of catalase subunits induced by the bioantioxidant; the latter was suggested to initiate the reaction of thiol--disulfide exchange with the enzyme. The problem of the compatibility of catalase with disulfide bioantioxidants is discussed.

Animals↗
PubMedDate not supplied

High catalase content of rabbit semen appears to be inherited.

Reactive oxygen species, as hydrogen peroxide, can be damaging to sperm. Most species have little protective catalase in their semen, but rabbit semen contains substantial amounts of catalase. The objective of the present study was to characterize a substantial number of Dutch rabbits for seminal content of catalase and determine whether differences were inherited. Usually, 4 or more semen samples were analyzed per male. Catalase was measured by a gasometric procedure. In Experiment 1, the correlation between duplicate determinations was r = .99, and between 2 sets of semen samples from 55 males it was r = .95. There was a significant difference (P < .05) among pairs of males from 6 litters. In Experiment 2, semen from each of 11 males collected at an interval of 1 year contained an average of 13 and 12 units of catalase per mL of semen in consecutive years. The correlation between pairs of samples was r = .85. This indicated that the condition was permanent, and possibly genetically controlled. Experiment 3 analyzed the catalase content of semen from 7 sires and 32 sons. The heritability of seminal catalase concentration was 0.48. These studies indicate that rabbit seminal plasma is high in catalase, and that a substantial portion of the differences among males are under genetic control.

Aging↗
PubMed2000

Peroxynitrite formation and decreased catalase activity in autoimmune MRL-lpr/lpr mice.

BACKGROUND: (MRL)-lpr/lpr mice spontaneously develop autoimmune disease characterized by arthritis and glomerulonephritis. Nitric oxide is postulated to play a role in the disease pathogenesis, as mice treated with the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine (NMMA) show markedly reduced manifestations of the disease. The purpose of this study was to examine the role of peroxynitrite in disease development in MRL-lpr/lpr mice. MATERIALS AND METHODS: We examined kidney extracts from control and MRL-lpr/lpr mice for nitrotyrosine by immunoblot with a rabbit polyclonal anti-nitrotyrosine antibody. Catalase activity was determined spectrophotometrically or by activity staining of native polyacrylamide gels. In some experiments, we studied the ability of peroxynitrite and other agents to modify purified catalase in vitro. RESULTS: Kidney extracts from diseased mice had elevated levels of nitrotyrosine, and decreased levels of catalase activity and protein, relative to control mice. MRL-lpr/lpr mice treated with NMMA in vivo had decreased levels of nitrotyrosine, and demonstrated a partial restoration of both catalase activity and protein levels. Treatment of catalase in vitro with peroxynitrite or tetranitromethane at pH 8.0 resulted in protein nitration and a decrease in catalase activity. 1,3-morpholinosydnonimine (SIN-1), a peroxynitrite generator, also decreased the activity of catalase. CONCLUSIONS: These observations suggest that peroxynitrite formation, with an associated decrease in catalase activity and general decrease in antioxidant enzyme activity, may result in increased levels of hydrogen peroxide and other oxidants that can contribute to the pathogenesis of disease in MRL-lpr/lpr mice.

Animals↗
PubMed2001

Catalase-overexpressing thymocytes are resistant to glucocorticoid-induced apoptosis and exhibit increased net tumor growth.

Glucocorticoids are used for the treatment of lymphoid neoplasms, taking advantage of the well-known ability of these compounds to cause apoptosis in lymphoid tissues. Previously, we have shown that dexamethasone, a synthetic glucocorticoid, causes a down-regulation of several antioxidant defense enzymes and proteins, including catalase and thioredoxin, concomitant with the induction of apoptosis in WEHI7.2 mouse thymoma cells. To test whether this down-regulation plays a critical role in the mechanism of steroid-induced apoptosis, WEHI7.2 cells were transfected with rat catalase. Two clones, expressing 1.4-fold and 2.0-fold higher catalase specific activity, respectively, when compared with vectoronly transfectants were selected for further study. An increase to 1.4-fold parental cell catalase activity delayed cell loss after dexamethasone treatment, whereas a 2.0-fold parental catalase activity prevented dexamethasone-induced cell loss for 48 h after treatment. Dexamethasone treatment of the WEHI7.2 cells stimulated a release of cytochrome c into the cytosol. Catalase-overexpressing cells showed a delay or lack of cytochrome c release from the mitochondria, which correlated temporally with the delay or prevention of cell loss in the culture after dexamethasone treatment. A decreased amount of cell death from WEHI7.2 cells overexpressing catalase was also seen in tumor xenografts in severe combined immunodeficient mice when compared with tumors from vector-only transfected cells. Similarly, thioredoxin-overexpressing WEHI7.2 cells, shown previously to be apoptosis resistant, showed decreased cell death in tumor xenografts. This resulted in larger tumors from cells overexpressing these proteins. Cell death in control transfectant tumor xenografts was primarily attributable to apoptosis. In contrast, the cell death we observed in tumors from thioredoxin- or catalase-overexpressing cells had a higher frequency of a nonapoptotic, nonnecrotic type of cell death termed para-apoptosis. These data suggest that: (a) oxidative stress plays a critical role in steroid-induced apoptosis prior to the commitment of the cells to undergo apoptosis; and (b) resistance to oxidative stress can contribute to tumor growth.

Animals↗
PubMed1979

Partial purification and properties of bovine heart catalase.

Catalase was partially purified (about 380-fold purification) from the post-mitochondrial supernatant of bovine heart and compared with catalases from bovine erythrocytes and bovine liver. The electrophoretic mobility in polyacrylamide gel (pH 8.0) of heart catalase was the same as that of erythrocyte catalase and was smaller than that of the liver enzyme. The heart catalase was indistinguishable from erythrocyte catalase in regard to the molecular weights of subunit polypeptides, the inhibition patterns produced by several catalase inhibitors, and specific activity. The pH-activity curve of heart catalase consisted of a characteristic biphasic pattern with a peak at pH 7.5 and a shoulder at pH 10.

Animals↗