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PubMed1997

Multiplicity of antioxidant enzyme catalase in mouse liver cells.

Multiplicity of catalase activity has been observed in crude homogenates from the tissue and cell lines of mouse liver by ethanol/Triton X-100/heat treatment. The five enzymatically active catalase bands were designated as CAT1, CAT2, CAT3, CAT4, and CAT5 with a nondenatured molecular mass of 270kDa, 258kDa, 229kDa, 210kDa, or 197kDa, respectively. Cultured mouse liver cell lines, mouse liver tissue homogenate, and pure mouse liver catalase showed only one catalase band (CAT1) after ethanol/Triton X-100 treatment at 4 degrees C for 72 hr. The same treatment but incubated at 37 degrees C for 72 hr yielded three bands (CAT2, CAT4, CAT5) in normal cell line, only one band (CAT5) in MNNG-transformed and SV40-transformed cells, two bands (CAT1, CAT4) in mouse liver tissue homogenates, and two bands (CAT1, CAT3) in pure mouse liver catalase. These five catalase bands were further biochemically characterized. The CAT1, CAT2, and CAT3 are sensitive to heat (68 degrees C, 1 min), while CAT4 and CAT5 are rather heat resistant. The sensitivity to catalase inhibitors, such as aminotriazole, azide, or cyanide varies among the isoforms. Protease inhibitors could prevent the formation of CAT3 and CAT4, but not CAT5. Treatment with protease, however, removed all forms of catalase except CAT5. We conclude from this study that the appearance of different catalase bands is likely due to epigenetic modification of the protein, particularly proteolysis. The lowered catalase activity in transformed cells might also be attributable to the loss of two catalase isoforms.

Animals↗
PubMed2000

Catalase evaluation in different human diseases associated with oxidative stress.

OBJECTIVE: Catalase is an enzyme present in most of the aerobic cells, it protects them from oxidative stress by catalyzing the rapid decomposition of hydrogen peroxide (H2O2) in two types of reactions depending on its peroxidatic and catalatic activities. The aim of this study was to measure the erythrocytes catalase activity by a reliable method in normal subjects with different age categories, and patients whom suffer from different diseases associated with oxidative stress (inflammatory, tumor, diabetes, cardiovascular diseases, anemia and Wilson's disease). METHODS: Erythrocytes catalase activity was measured, by peroxidatic method (Johansson-Borg method), in 210 apparently healthy subjects, (117 males and 93 females). The range of their ages was from 7 months to 65 years, and in 454 patients their ages ranged from 3 months to 74 years, whom suffer from the above mentioned diseases which resulted in oxidative stress. The comparison had been made between the Johansson-Borg and the UV catalase methods. RESULTS: Strong correlation was found between the two methods, peroxidatic and catalatic (r=0.99, P<0.0001), but the catalase solutions were unstable when the temperature was raised. The normal range of catalase was found to be 2869+1039 u/g Hb. It was found that the catalase activity increased in the studied morbidity groups (eg. 188% in oxidative anemia). An accepted decrease 50% was noted in catalase activity when Vitamin E was administered to anemic patients suffering from oxidative stress. CONCLUSION: There was an increase in catalase activity in all studied patients suffering from oxidative stress (cardiovascular diseases, diabetes, tumor, inflammation, dermatological diseases, anemia and Wilson's disease). The catalase activity was not affected by age, sex or the anticoagulant agent, which was used to collect the blood samples. It was found that the Vitamin E supplement decreased the catalase activity and improved the state of anemic oxidative stress patients.

Adolescent↗
PubMed1995

[The property of tetracyclines to induce methemoglobin formation in erythrocytes and to inactivate catalase when exposed to radiation in the visible range].

When tetracycline and chlortetracycline were incubated an a dark room in the presence of erythrocytes with erythrocytic catalase completely inactivated by sodium azide, the antibiotics induced methemoglobin formation in them. If the catalase was not inactivated, no such phenomenon was observed. This meant that after the penetration into the erythrocytes the tetracyclines induced in them the generation of hydrogen peroxide which was the immediate cause of the methemoglobin formation. The effect of the methemoglobin formation on the erythrocytes was also induced by tetracycline without the catalase blocking when the erythrocytes were exposed to the antibiotic and visible light. The effect was not mediated by the hydrogen peroxide action on hemoglobin in the erythrocytes as it was in the previous case, since even when catalase was added exogenously to the suspension medium it induced no suppression of the methemoglobin formation in the erythrocytes. Additional introduction of exogenous catalase to the erythrocyte hemolysates prior to the exposure did not either influence the methemoglobin formation photoinduced in them by tetracycline. The effect manifestation was not practically influenced by L-histidine, mannitol or ethanol used as traps for the radicals which could form during the antibiotic exposure to visible light in the suspension medium. The calorimetric estimation of the catalase functional properties showed that when exposed to visible light in the presence of the enzyme (a commercial product) tetracycline induced its inactivation. It was indicated that the catalase photoinactivation by tetracycline was due not to a steady decrease of the activity of every molecule of the enzyme but to a dislodge of separate molecules among the active ones, i.e. a one-fold change of the enzyme molecule from the initial active state to the completely inactive one. The catalase photoinactivation by tetracycline was not eliminated by L-histidine or comparatively high concentrations of mannitol but was entirely eliminated by ethanol used in relatively low concentrations. When the erythrocytes were exposed to visible light in the presence of tetracycline, the effect of the catalase photoinactivation by the antibiotic was also observed. In this case the same as in the experiments with isolated catalase, ethanol as well protected the enzyme from the photoinactivation by tetracycline. The tetracycline photoeffects on hemoglobin, catalase and possibly other heme-containing proteins were likely realized in the immediate closeness of their hemes. The photoeffects of the tetracyclines associated with the heme-containing proteins possibly play a certain role in the phototoxicity of the antibiotics.

Animals↗
PubMed1997

Conjugation of catalase to a carrier antibody via a streptavidin-biotin cross-linker.

Targeting of catalase could be useful in antioxidative protection of cells challenged with H2O2. In the present study we conjugated catalase to a carrier model antibody using a biotin-streptavidin (SA) cross-linker and characterized the functional activity of the conjugate. Neither biotinylation nor conjugation with SA decreased the enzymic activity of catalase. Further coupling of radiolabelled biotinylated catalase (b-catalase) to biotinylated antibody (b-Ab) via SA using a two-step conjugation procedure did not change enzymic activity of b-catalase. b-Ab-SA-b-catalase specifically bound to antigen-coated plastic wells, but not to albumin-coated plastic wells. Substitution of b-Ab with control biotinylated IgG (b-IgG) abrogated binding of the catalase to the antigen. H2O2 was degraded in antigen-coated wells preincubated with b-Ab-SA-b-catalase, but not with b-IgG-SA-b-catalase. Thus b-Ab-SA-b-catalase specifically binds to immobilized antigen and degrades H2O2 after binding to the target. The methodology described in the present paper may be useful for the development of a novel strategy for antioxidant therapy.

Animals↗
PubMed1989

Regulation of Catalase Activity in Leaves of Nicotiana sylvestris by High CO(2).

The effect of high CO(2) (1% CO(2)/21% O(2)) on the activity of specific forms of catalase (CAT-1, -2, and -3) (EA Havir, NA McHale [1987] Plant Physiol 84: 450-455) in seedling leaves of tobacco (Nicotiana sylvestris, Nicotlana tabacum) was examined. In high CO(2), total catalase activity decreased by 50% in the first 2 days, followed by a more gradual decline in the next 4 days. The loss of total activity resulted primarily from a decrease in CAT-1 catalase. In contrast, the activity of CAT-3 catalase, a form with enhanced peroxidatic activity, increased 3-fold in high CO(2) relative to air controls after 4 days. Short-term exposure to high CO(2) indicated that the 50% loss of total activity occurs in the first 12 hours. Catalase levels increased to normal within 12 hours after seedlings were returned to air. When seedlings were transferred to air after prolonged exposure to high CO(2) (13 days), the levels of CAT-1 catalase were partially restored while CAT-3 remained at its elevated level. Levels of superoxide dismutase activity and those of several peroxisomal enzymes were not affected by high CO(2). Total catalase levels did not decline when seedlings were exposed to atmospheres of 0.04% CO(2)/5% O(2) or 0.04% CO(2)/1% O(2), indicating that regulation of catalase in high CO(2) is not related directly to suppression of photorespiration. Antibodies prepared against CAT-1 catalase from N. tabacum reacted strongly against CAT-1 catalase from both N. sylvestris and N. tabacum but not against CAT-3 catalase from either species. This observation, along with the rapid changes in CAT-1 and the much slower changes in CAT-3 suggest that one form is not directly derived from the other.

Journal Article↗
PubMed1990

Catalase and superoxide dismutase of root-colonizing saprophytic fluorescent pseudomonads.

Root-colonizing, saprophytic fluorescent pseudomonads of the Pseudomonas putida-P. fluorescens group express similar levels of catalase and superoxide dismutase activities during growth on a sucrose- and amino acid-rich medium. Increased specific activities of catalase but not superoxide dismutase were observed during growth of these bacteria on components washed from root surfaces. The specific activities of both enzymes were also regulated during contact of these bacteria with intact bean roots. Increased superoxide dismutase and decreased catalase activities were observed rapidly, by 10 min upon inoculation of cells onto intact bean roots. Catalase specific activity increased with time to peak at 12 h before declining. By 48 h, the cells displayed this low catalase but maintained high superoxide dismutase specific activities. Catalase with a low specific activity and a high superoxide dismutase activity also were present in extracts of cells obtained from 7-day-old roots colonized from inoculum applied to seed. This specific activity of superoxide dismutase of root-contacted cells was about fourfold-higher in comparison to cells grown on rich medium, whereas the specific activity for catalase was reduced about fivefold. A single catalase isozyme, isozyme A, and one isozyme of superoxide dismutase, isozyme 1, were detected during growth of the bacteria on root surface components and during exposure of cells to intact bean roots for 1 h. An additional catalase, isozyme B, was detected from bacteria after exposure to the intact bean roots for 12 h. Catalase isozyme A and superoxide dismutase isozyme 1 were located in the cytoplasm and catalase band B was located in the membrane of P. putida.

Journal Article↗
PubMed2002

Inhibition of experimental pulmonary metastasis by controlling biodistribution of catalase in mice.

In a previous study, we showed that targeted delivery of bovine liver catalase to hepatocytes by direct galactosylation augmented the inhibitory effect of the enzyme on experimental hepatic metastasis of colon carcinoma cells (unpublished data). Here, we examined the ability of catalase to inhibit tumor metastasis to the lung by controlling its biodistribution. Four types of catalase derivative, Gal-CAT, Man-CAT, Suc-CAT and PEG-CAT, were synthesized. Experimental pulmonary metastasis was induced in mice by i.v. injection of 1 x 10(5) colon 26 tumor cells. An i.v. injection of catalase (35,000 units/kg) partially, but significantly, decreased the number of colonies in the lung 2 weeks after tumor injection, from 93 +/- 29 (saline injection) to 63 +/- 23 (p < 0.01). Suc-CAT, Man-CAT and Gal-CAT showed effects similar to those of catalase on the number of colonies. However, PEG-CAT greatly inhibited pulmonary metastasis to 22 +/- 11 (p < 0.001). Furthermore, s.c. injection of catalase also greatly inhibited metastasis (11 +/- 6, p < 0.001). Neither inactivated catalase nor BSA showed any effects on the number of metastatic colonies, indicating that the enzymatic activity of catalase to detoxify H(2)O(2) is the critical factor inhibiting metastasis. (111)In-PEG-CAT showed a sustained concentration in plasma, whereas s.c.-injected (111)In-catalase was slowly absorbed from the injection site. These results suggest that retention of catalase activity in the circulation is a promising approach to inhibit pulmonary metastasis.

Animals↗
PubMed2007

Downregulation of catalase by reactive oxygen species via PI 3 kinase/Akt signaling in mesangial cells.

Reactive oxygen species (ROS) contribute to many glomerular diseases by targeting mesangial cells. ROS have been shown to regulate expression of many antioxidant enzymes including catalase. The mechanism by which the expression of catalase protein is regulated by ROS is not precisely known. Here we report that increased intracellular ROS level by hydrogen peroxide (H(2)O(2)) reduced the expression of catalase. H(2)O(2) increased phosphorylation of Akt kinase in a dose-dependent and sustained manner with a concomitant increase in the phosphorylation of FoxO1 transcription factor. Further analysis revealed that H(2)O(2) promoted rapid activation of phosphatidylinositol (PI) 3 kinase. The PI 3 kinase inhibitor Ly294002 and expression of tumor suppressor protein PTEN inhibited Akt kinase activity, resulting in the attenuation of FoxO1 phosphorylation and preventing the downregulating effect of H(2)O(2) on catalase protein level. Dominant negative Akt attenuated the inhibitory effect of H(2)O(2) on expression of catalase. Constitutively active FoxO1 increased the expression of catalase. However, dominant negative FoxO1 inhibited catalase protein level. Catalase transcription was reduced by H(2)O(2) treatment. Furthermore, expression of dominant negative Akt and constitutively active FoxO1 increased catalase transcription, respectively. These results demonstrate that ROS downregulate the expression of catalase in mesangial cells by PI 3 kinase/Akt signaling via FoxO1 as a target.

Animals↗
PubMed1994

Interaction of phlorizin, a potent inhibitor of the Na+/D-glucose cotransporter, with the NADPH-binding site of mammalian catalases.

Phlorizin is a reversible inhibitor of the renal and small intestinal Na+/D-glucose cotransporter. In an attempt to purify the Na+/D-glucose cotransporter from a pig kidney brush border membrane fraction, we used an Affi-Gel affinity chromatography column to which 3-aminophlorizin had been coupled. A protein, composed according to crosslinking experiments of at least 3 subunits of molecular weight 60 kDa, was found to bind specifically to the phlorizin column. This protein was subsequently identified as catalase by sequence homology of three of its tryptic fragments to the sequence of several mammalian catalases as well as by its enzymatic activity. Although bovine liver catalase was bound tightly to the affinity matrix, phlorizin had no effect on the ability of the enzyme to degrade H2O2. In contrast, the Aspergillus niger and Neurospora crassa catalases did not bind to the phlorizin column. This difference may be related to the fact that mammalian catalases, but not the fungal catalases, contain an NADPH binding site with a yet unknown function. Interestingly, bovine liver catalase could be eluted with 50 microM NADPH from phlorizin columns. Irradiation in the presence of [3H]4-azidophlorizin allowed photolabeling of bovine liver catalase, which was prevented by the presence of 10 microM NADPH. After digestion of photolabeled catalase with chymotrypsin, a radioactive peptide was detected that was absent in catalase protected with NADPH. Docking simulations suggested that phlorizin can bind to the NADPH binding site with high affinity.

Amino Acid Sequence↗
PubMed1995

Inactivation of an animal and a fungal catalase by hydrogen peroxide.

We have quantitatively compared the rates of peroxide-dependent inactivation of bovine liver catalase and Aspergillus niger catalase as class representatives of catalases that contain tightly bound NADPH and those that do not. Inactivation of these catalases in the presence of ethanol has also been quantitated in an effort to assess the importance of compound II, an inactive form of bovine liver catalase, in the inactivation reaction. The values of k2, the second-order rate constant for inactivation calculated for the bovine enzyme, in the absence and presence of ethanol, respectively, were 8.9 +/- 0.26 and 8.5 +/- 0.27 M-1 min-1. In contrast, the values for the A. niger enzyme were 0.51 +/- 0.069 and 10.5 +/- 0.32 M-1 min-1. The A. niger enzyme is more stable toward hydrogen peroxide-induced inactivation than the liver enzyme. The A. niger enzyme is markedly destabilized by 20 mM ethanol, whereas the inactivation of the liver enzyme is unaffected by ethanol. Reaction of bovine liver catalase with ethyl hydroperoxide produced the characteristic absorption spectrum of compound I and in the absence of ethanol the spectrum associated with compound II. In contrast, the fungal enzyme developed compound I spectrum but spectral changes that might be ascribed to compound II were barely detected in the Soret region. Spectral changes for A. niger catalase in the visible region were modified by the presence of ethanol but could not be clearly correlated with the bovine catalase compound II spectra either in the presence or absence of ethanol. The stability of the fungal and bovine catalases in the presence of hydrogen peroxide is quantitatively documented. The enzymes are also shown to be different in their response to ethanol and in the formation of compound II-like species with ethyl hydroperoxide. It appears unlikely that compound II is an intermediate in the hydrogen peroxide-mediated inactivation reaction of either catalase under catalatic assay conditions.

Animals↗
PubMedDate not supplied

Cloning, characterization and phenotypic expression in Escherichia coli of catF, which encodes the catalytic subunit of catalase isozyme CatF of Pseudomonas syringae.

The phytophathogenic, gram-negative bacterium Pseudomonas syringae pv. syringae 61 contains three isozymes of catalase (EC 1.11.1.6), which have been proposed to play a role in the bacterium's responses to various environmental stresses. To study the role of individual isozymes, the gene coding for the catalytic subunit of one catalase isozyme was cloned from a cosmid library hosted in Escherichia coli DH5 alpha by using a designed catalase-specific DNA probe for the screening. One out of four clones with a catalase-positive genotype was subcloned and a pUC19-based 2.7 x 10(3)-base (2.7-kb) insert subclone, pMK3E5, was used to transform catalase-deficient E. coli strain UM255 (HPI-, HPII-). The transformants contained a single isozyme of catalase that had electrophoretic and enzymic properties similar to catalase isozyme CatF from P. syringae pv. syringae 61. Analysis of the sequenced 2.7-kb insert DNA revealed six putative open-reading frames (ORF). The 1542-base-pair DNA sequence of ORF2, called catF, encodes a peptide of 513 amino acid residues with a calculated molecular mass of 66.6 kDa. The amino acid sequence deduced from catF had homology to the primary structure of true catalases from mammals, plants, yeasts and bacteria. The activity of the recombinant catalase was inhibited by 3-amino-1,2,4-triazole and azide and stimulated by chloramphenicol. The N terminus contained a signal sequence of 26 amino acids necessary for secretion into the periplasm, a so-far unique property of Pseudomonas catalases.

Amino Acid Sequence↗
PubMed1984

On the topology of the catalase biosynthesis and -degradation in the guinea pig liver. A cytochemical study.

The biosynthesis, transport and degradation of catalase have been studied in the guinea pig liver parenchymal cell using 2-allyl-2-isopropylacetamide (AIA) as an inhibitor of de novo formation of catalase. Total catalase activity was assayed biochemically; cytoplasmic catalase was measured microspectrophotometrically after quantitative diaminobenzidine staining of the liver. By morphometry, number and size of peroxisomes in catalase stained sections were determined. From our data we conclude that (1) the final step in the catalase formation takes place inside peroxisomes, (2) catalase is transported from the peroxisomes into the cytoplasm, (3) in the cytoplasm catalase is degraded. These conclusions in part confirm the topological model on the intracellular catalase biosynthesis pathway of Lazarow and de Duve (1973) except for the presence of cytoplasmic catalase which is released from the peroxisomes as proposed earlier by Jones and Masters (1975).

Allylisopropylacetamide↗
PubMed2006

Catalase expression in pancreatic alpha cells of diabetic and non-diabetic mice.

The pancreatic islet beta cells are very sensitive to oxidative stress, probably due to the extremely low level of anti-oxidant enzymes, particularly catalase. In contrast to beta cells, pancreatic alpha cells are significantly more resistant to diabetogenic toxins. However, whether alpha cells express a different level of catalase is not known. The aim of this study was to evaluate catalase expression in alpha cells of diabetic and non-diabetic mice. Diabetes was induced by a single injection of streptozotocin. After 3 weeks of persistent hyperglycemia, pancreatic tissues were collected. Catalase localization in alpha cells was identified by a dual-immunofluorescence staining with anti-glucagon and anti-catalase antibodies. In intact mice, intensive catalase and glucagon immunostaining was found in the peripheral area of islets. Merged images of glucagon and catalase show their localization in the same cell type, namely, alpha cells. Confocal microscopy indicated that the glucagon and catalase staining was distributed throughout the cytoplasm. Similar co-expression of catalase and glucagon was found in the alpha cells of diabetic animals. The results of this study show the intensive catalase expression in alpha cells of diabetic and non-diabetic mice. This knowledge may be useful to better understand the defense mechanisms of pancreatic alpha cells against oxidative stress.

Animals↗
PubMed2006

Inhibition of adhesion and proliferation of peritoneally disseminated tumor cells by pegylated catalase.

Hydrogen peroxide may aggravate the peritoneal dissemination of tumor cells by activating the expression of a variety of genes. In this study, we used pegylated catalase (PEG-catalase) to examine whether prolonged retention of catalase activity within the peritoneal cavity is effective in inhibiting peritoneal dissemination in mouse models. Murine B16-BL6 cells or colon 26 cells labeled with firefly luciferase gene were inoculated intraperitoneally into syngeneic mice. Compared with unmodified catalase, PEG-catalase was retained in the peritoneal cavity for a long period after intraperitoneal injection. A single injection of PEG-catalase just before tumor inoculation significantly reduced the number of the tumor cells at 1 and 7 days. The changes in the expression of molecules involved in the metastasis were evaluated by real time quantitative PCR analysis. Inoculation of the tumor cells increased the expression of intercellular adhesion molecule (ICAM)-1 in the greater omentum, which was inhibited by PEG-catalase. An injection of PEG-catalase at 3 days after tumor inoculation also reduced the number of the tumor cells, suggesting that processes other than the adhesion of tumor cells to peritoneal organs are also inhibited. Daily doses of PEG-catalase significantly prolonged the survival time of tumor-bearing mice. These results indicate that intraperitoneal injection of PEG-catalase inhibits the multiple processes of peritoneal dissemination of tumor cells by scavenging hydrogen peroxide in the peritoneal cavity.

Abdominal Neoplasms↗
PubMed1991

Dose- and time-dependent effect of an acute 3-amino-1,2,4-triazole injection on rat brain catalase activity.

The results presented in this study demonstrate a progressive inhibition of rat brain catalase activity by AT in vivo. Furthermore, the inhibition of brain catalase by AT demonstrates the presence of hydrogen peroxide in brain, since AT inhibits catalase in the presence of this compound. The rate of inhibition of catalase seems to be dependent upon the rate by which H2O2 is generated. A time course study showed slower onset of the inhibition of brain as compared to liver catalase, possibly reflecting tissue hydrogen peroxide levels or, alternatively, a rate-limiting penetration of AT into brain and into the catalase compartment. The presence of AT in brain was confirmed over the time period of the observed inhibition of brain catalase. Catalase inhibitors are of particular interest in the study of the physiological role of catalase. This study further supports the use of AT in investigations designed to further understand the role of brain catalase.

Amitrole↗
PubMed1995

Catalase and hydrogen peroxide cytotoxicity in cultured cardiac myocytes.

We examined the role of intracellular catalase activity in modulating hydrogen peroxide (H2O2)-induced cytotoxicity in cultured chick embryo cardiac myocytes. Injury was quantitated by release of lactate dehydrogenase (LDH). Application of 1.5 mM H2O2 to myocytes caused LDH release beginning at 2 h. Inactivation or inhibition of catalase with aminotriazole or sodium azide increased LDH release but did not cause earlier release. Free catalase which entered or became associated with myocytes, but not catalase bound to agarose beads, which did not enter or become associated with myocytes, was protective. Separate experiments demonstrated that myocyte catalase activity decreased by 27% between 1 and 4 h of H2O2 exposure. Treatment with aprotinin, a protease inhibitor, prevented the H2O2-induced fall in catalase activity at 4 h but treatment with deferoxamine, an iron chelator, had no effect on catalase activity. Thus, with exposure of cardiac myocytes to H2O2, the magnitude of the cytotoxicity is modulated by endogenous or cell associated exogenous catalase. It is proposed that in addition to excessive accumulation of H2O2, a reduction intracellular catalase activity may be required before substantial cell injury occurs during H2O2 exposure. Activation of proteases may cause the reduction in catalase activity in this setting.

Animals↗
PubMed1987

A study of the catalase monomer produced by lyophilization.

Lyophilization of Dounce and Mourtzikos beef liver catalase (Prep. Biochem. 11 (1981) 501-523) under specified conditions produced conformationally altered but not completely denatured catalase monomer which retained both significant catalatic activity and peroxidatic activity towards ethanol. The same lyophilization procedure used with Sigma Co. catalase produced a mixture of conformationally altered catalase monomer and conformationally altered tetramer which showed still higher catalatic and peroxidatic activities; this was attributed to the presence of the altered tetramer. The catalase monomer obtained by the use of Dounce and Mourtzikos catalase is completely reducible by dithionite, as shown by the two-banded spectrum of the reduced material, but apparently retains enough of its native conformation to show some enzymatic activity, since the fully denatured monomer shows no catalatic or peroxidatic activity towards ethanol. The conformationally altered catalase tetramer, which shows more enzymatic activity than the monomer, evidently retains a higher proportion of its native conformation than the monomer, but still appears to be fully reducible with dithionite. Horseradish peroxidase after reduction with dithionite shows spectral bands at positions close to those of reduced lyophilized catalase, but the relative band heights and contours are different. A possible explanation for the observed differences in lyophilization products depending on the starting material (Sigma Co. catalase versus catalase of Dounce and Mourtzikos) is presented.

Animals↗
PubMed1993

Expression of human catalase in acatalasemic murine SV-B2 cells confers protection from oxidative damage.

Reactive oxygen species have been implicated in aerobic organisms as causative agents in damage to DNA, proteins, and lipids. Catalase is a major enzyme in the defense against such oxidant damage. To determine whether increased catalase expression confers greater resistance to oxidant stress, a eukaryotic expression vector harboring a human catalase cDNA clone was constructed. Acatalasemic murine fibroblasts were then co-transfected with that catalase expression vector and pSV2-neo, and successfully transfected cells were identified by their ability to grow in the presence of geneticin. Clones that contained integrated copies of the catalase expression vector were identified by Polymerase Chain Reaction (PCR) analysis. Stably transfected geneticin-resistant cell lines that overexpressed catalase in potentially positive cell lines were confirmed by catalase enzyme assays. To examine the physiological relevance of catalase overexpression, cells were exposed to oxidant stresses (hydrogen peroxide and hyperoxia), and survival rates were determined. Results demonstrated a significant resistance to oxidative stress in cells overexpressing catalase when compared to controls. These transfected cell lines will provide important models for further evaluation of the role of catalase in protecting cells against the toxic effects of oxygen-derived free radicals and their derivatives.

Acatalasia↗