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PubMed2002

Regulation of catalase enzyme activity by cell signaling molecules.

Mitogenic cell proliferation requires a rapid and transient H2O2 generation, which is blocked by catalase or PKA activators. Previously, we observed that anemic HIV(+) individuals expressed acidic pIs of catalase in RBC with significantly high activities [Mol Cell Biochem 165: 77-81, 1996]. These findings led us to hypothesize that cell signaling molecules regulate catalase to control cell mitogenesis. To test the hypothesis, we determined (i) whether RBC counts correlate with their catalase activities, (ii) whether protein kinases and phosphatases alter catalase activity in vitro, and (iii) whether protein kinase activators increase catalase activity to suppress proliferation of cultured cells. The results indicated that RBC counts inversely correlated with RBC catalase activities in both HIV(+) (r: -0.6769, r2: 0.4582, n: 69 male, p < 0.0001) and HIV(-) (r: -0.3827, r2: 0.1464, n: 177 male, p < 0.0001) populations. Catalytic PKA, PKC and Casein Kinase II, but none of PKG, Ca2+/calmodulin kinase II and p34cdc/cyclinB, rapidly elevated catalase activity in vitro by up to 2-fold. Whereas a major CAT subunit (60 kDa) showed immunoreactive phosphoserine and phosphothreonine, the kinases- and gamma-32P-ATP-dependent phosphorylation occurred with a minor component (110 kDa). Among PKC isozymes examined, PKCzeta was the most effective modulator followed by PKCgamma, and protein phosphatase 1gamma and 2A decreased the catalase activity. PKA and PKCzeta activators of forskolin and okadaic acid increased catalase activity and 110 kDa expression in NIH3T3 cells up to 2.4-fold and suppressed the cell growth, showing an inverse correlation of the indices (r: -0.9286, r2: 0.8622, n: 18, p < 0.0001). Taken together, these results suggest for the first time that catalase is under the regulation of cell signaling molecules and capable of modulating mitogenic cell proliferation.

3T3 Cells↗
PubMed2001

Identification of two highly divergent catalase genes in the fungal tomato pathogen, Cladosporium fulvum.

Catalases of pathogenic micro-organisms have attracted attention as potential virulence factors. Homology-based screens were performed to identify catalase genes in the fungal tomato pathogen Cladosporium fulvum. Two highly divergent genes, Cat1 and Cat2, were isolated and characterized. Cat1 codes for a putative 566-amino-acid catalase subunit and belongs to the gene family that also encodes the mainly peroxisome-localized catalases of animal and yeast species. Cat2 codes for a putative catalase subunit of 745 amino acids and belongs to a different gene family coding for the large-subunit catalases similar to ones found in bacteria and filamentous fungi. Neither catalase had an obvious secretory signal sequence. A search for an extracellular catalase was unproductive. The Cat1 and Cat2 genes showed differential expression, with the Cat1 mRNA preferentially accumulating in spores and the Cat2 mRNA preferentially accumulating in response to external H(2)O(2). With Cat2-deleted strains, activity of the Cat2 gene product (CAT2) was identified among four proteins with catalase activity separated on non-denaturing gels. The CAT2 activity represented a minor fraction of the catalase activity in spores and H(2)O(2)-stressed mycelium, and no phenotype was observed for Cat2-deleted strains, which showed a normal response to H(2)O(2) treatment. These results indicate the existence of a complex catalase system in C. fulvum, with regard to both the structure and regulation of the genes involved. In addition, efficient C. fulvum gene-replacement technology has been established.

Amino Acid Sequence↗
PubMed2004

Correlation between the catalase level in tumor cells and their sensitivity to N-beta-alanyl-5-S-glutathionyl-3,4-dihydroxyphenylalanine (5-S-GAD).

N-beta-Alanyl-5-S-glutathionyl-3,4-dihydroxyphenylalanine (5-S-GAD) exhibits selective cytotoxicity toward certain human tumor cell lines. 5-S-GAD has been shown to release hydrogen peroxide autonomously. Hydrogen peroxide is converted to water and oxygen by catalase. The purpose of this study is to determine whether or not 5-S-GAD exhibits selective cytotoxicity toward tumor cells with low catalase levels, but not toward ones with high catalase levels. We transfected MDA-MB-435S cells, which are sensitive to 5-S-GAD, with catalase cDNA to establish high catalase producer cells, and then examined their 5-S-GAD sensitivity. Similarly, we repressed catalase expression in T47D cells, which are insensitive to 5-S-GAD, by catalase RNA interference to create low catalase producer cells, and then examined their 5-S-GAD sensitivity. We show that the overexpression of catalase made MDA-MB-435S cells insensitive to 5-S-GAD, whereas the suppression of catalase made T47D cells sensitive to 5-S-GAD. The cellular catalase level was found to be crucial for cell sensitivity to 5-S-GAD.

Base Sequence↗
PubMed1993

Protection of human endothelial cells from oxidant injury by adenovirus-mediated transfer of the human catalase cDNA.

In a variety of disorders, endothelial cells are exposed to high levels of oxidants, generated within the cells and/or consequent to local inflammation. In the context of the sensitivity of endothelial cells to oxidant stress, particularly related to H2O2, we have designed a replication deficient recombinant adenovirus containing the human catalase cDNA (AdCL) to transfer the catalase cDNA to the endothelial cells, in order to augment intracellular anti-H2O2 protection. Human umbilical vein endothelial cells that were not infected or infected with control adenovirus maintained low levels of catalase mRNA. Endothelial cells infected with AdCL expressed AdCL-driven exogenous catalase mRNA, as early as 24 hr and at least for 7 days. Catalase protein levels were increased significantly over controls in cells infected with AdCL, as were catalase activity levels, with catalase activity correlated closely with levels of catalase protein. Importantly, when the endothelial cells were exposed to 500 microM H2O2, all the AdCL infected endothelial cells survived, compared to only 37% of the control cells. Thus, a recombinant adenovirus containing the human catalase cDNA is able to infect human endothelial cells in vitro and express high levels of functional intracellular catalase, protecting the cells against H2O2-mediated oxidant stress. These observations support the feasibility of the transfer of catalase cDNA to human endothelium to protect against oxidant injury.

Adenoviridae↗
PubMed1980

The interactions of thiol compounds with porcine erythrocyte catalase.

The effects of thiol compounds on the conformation of porcine erythrocyte catalase were examined. The thiol compounds showed two types of reactivity with the catalase in terms of changes in absorption spectra. One is characterized by the appearance of a new absorption maximum at 595 nm; this was seen with 2-mercaptoethanol (designated as inactive catalase type I). The other is characterized by new maxima at 535 and 570 nm, and this was seen with reduced glutathione, dithiothreitol, cysteine, and cysteamine (inactive catalase type II). The thiol compounds caused gradual inactivation of catalase, correlating with the enhancement of the absorption maximum at 595 nm or 570 nm. Removal of excess thiol reagents from the reaction mixtures caused partial recovery of activity, which was more marked with inactive catalase type II. Similar reversibility was observed in the absorption, CD and MCD spectra, whereas reversibility was not observed for inactive catalase type I. The MCD spectra suggested conversion of heme groups from a high to a low spin state on incubation with thiols, e.g., reduced glutathione, leading to inactive catalase type II. alpha-Helical conformation of the polypeptide backbone and titratable free SH groups in the catalase molecule were unaffected by all these thiol treatments. It is suggested that "active oxygen" which may be produced on incubation of catalase with thiol compounds, was responsible for the formation of inactive catalase type II.

Animals↗
PubMed1998

Binding of a bovine oviductal fluid catalase to mammalian spermatozoa.

Hydrogen peroxide (H2O2) is a reactive oxygen species that at low concentration is toxic to sperm. H2O2 inhibits not only sperm viability but also the acrosome reaction, sperm-egg binding, and oocyte penetration. Catalase activates the decomposition of H2O2 into water and oxygen, thus removing an initiator of free radical chain reactions leading to lipid peroxidation. Since the oviduct is known to enhance sperm survival, we hypothesized that it might secrete catalase. We found that oviductal fluid, harvested from washed cells collected at the slaughterhouse, possessed catalase-specific activity that varied during the estrous cycle. Catalase activity increased during the cycle and reached its maximal level just before ovulation (Days 18-20). No significant difference in activity was seen between fluid from the isthmus and that from the ampulla. Indirect immuno-staining of spermatozoa incubated in the oviductal fluid revealed the association of catalase in the region of the acrosomal cap. Addition of a commercial antibody directed against bovine liver catalase completely inhibited catalase activities from the oviductal fluid. Catalase activity was also detected in porcine oviductal fluid, human oviductal fluid, and cervical mucus. Western blots of oviductal fluid probed with the anti-catalase antibody revealed two major bands at 60 and 40 kDa. An immunoaffinity column was used to purify oviductal catalase, showing a unique band at about 60 kDa when analyzed by SDS-PAGE. The purified protein was incubated with bovine, boar, and human sperm, and Western blots of these sperm after several washes detected a band at 60 kDa, indicating that the protein was bound to sperm membranes. However, bovine liver catalase did not bind to sperm. Since H2O2 is one of the key reactants in the chain reaction of free radical production, this enzyme may play an important role in sperm survival within the female tract.

Animals↗
PubMed2002

Redundancy, phylogeny and differential expression of Histoplasma capsulatum catalases.

Histoplasma capsulatum produces an extracellular catalase termed M antigen, which is similar to catalase B of Aspergillus and Emericella species. Evidence is presented here for two additional catalase isozymes in H. capsulatum. Catalase A is highly similar to a large-subunit catalase in Aspergillus and Emericella species, while catalase P is a small-subunit catalase protein with greatest similarity to known peroxisomal catalases of animals and Saccharomycotina yeasts. Complete cDNAs for the CATA and CATP genes (encoding catalases A and P, respectively) were isolated. The transcriptional expression of the H. capsulatum CATA, CATB (M antigen) and CATP genes was assessed by Northern blot hybridizations on total RNA. Results at the transcript levels for these genes are shown for three conditions: cell morphology (mycelial versus yeast phase cells), oxidative stress (in response to a challenge with H(2)O(2)) and carbon source (glucose vs glycerol). Collectively, these results demonstrated regulation of CATA by both cell morphology and oxidative stress, but not by carbon source, and regulation of CATB and CATP by carbon source but not cell morphology or oxidative stress. A phylogenetic analysis of presently available catalase sequences and intron residences was done. The results support a model for evolution of eukaryotic monofunctional catalase genes from prokaryotic genes.

Amino Acid Sequence↗
PubMed1999

The expression of the pathogenic yeast Candida albicans catalase gene in response to hydrogen peroxide.

The catalase gene of the pathogenic yeast Candida albicans was cloned and its expression was examined. Activity of the catalase was detected when cells which were in the early logarithmic stage were treated with hydrogen peroxide. Additionally, activity was detected without any treatment to cells in the late logarithmic and stationary phases. When cells were cultured in galactose, glycerol, or ethanol, catalase activity was always observed without the hydrogen peroxide treatment, suggesting that glucose represses the induction of catalase expression. To elucidate the molecular mechanism of catalase expression, the putative gene for catalase and its 5' untranscribed region were cloned. Sequences of the gene and its potential regulatory region revealed several motifs, including a GC box-like element and stress-responsive element (STRE), which could be involved in the transcriptional regulation. Northern analysis showed that hydrogen peroxide and sorbitol activated transcription of the catalase. On the other hand, treatment of glucose strictly repressed the expression of the catalase even when co-treated with hydrogen peroxide. The expression of catalase against treatment with hydrogen peroxide took place very quickly and decreased slowly in the experimental condition adopted here. From these results, we assumed that the expression of the catalase in Candida albicans is regulated by various environmental conditions via motifs for transcriptional activation as in other yeast catalases.

Amino Acid Sequence↗
PubMed1982

Regulation of synthesis of catalases and iso-1-cytochrome c in Saccharomyces cerevisiae by glucose, oxygen and heme.

The regulation of the hemoproteins catalase T, catalase A and iso-1-cytochrome c was studied in the yeast Saccharomyces cerevisiae. Levels of catalase T and catalase A mRNAs are low or undetectable in anaerobic and heme-deficient cells, and in wild type strains grown on high glucose concentrations. Regulatory mutants (cgr4 and cas1), which have previously been shown to have high catalase T activity when grown in the absence of oxygen or on high glucose concentrations, have high levels of catalase T mRNA when grown under glucose repression conditions. Whereas no catalase T mRNA could be detected in a heme-deficient (ole3) single mutant, double mutants (ole3 cgr4) and (ole3 cas1) contain mature catalase T mRNA. Catalase T and A mRNAs are accumulated rapidly during adaptation of anaerobic cells to oxygen. Anaerobic and heme-deficient cells lack or have extremely low levels of iso-1-cytochrome c mRNA, which, like catalase mRNAs, is accumulated rapidly during oxygen adaptation. The results obtained demonstrate that glucose, oxygen and heme regulate the synthesis of the hemoproteins studied by controlling mRNA levels. In addition, posttranscriptional, probably translational control has to be postulated at least in the case of catalases, to explain the results obtained.

Catalase↗
PubMed1988

Detection of a novel catalase in extracts of Mycobacterium avium and Mycobacterium intracellulare.

A novel class of catalase, which differs from the previously described M- and T-catalases of mycobacteria, was detected in strains of Mycobacterium avium and M. intracellulare. Designated A-catalase, this enzyme resisted inactivation at 68 degrees C, was inactivated by 3-amino-1,2,4-triazole (aminotriazole), and exhibited no peroxidase activity. All of these properties distinguished the enzyme from T-catalase. The A-catalase exhibited a Km of 70 mM H2O2, which is between the upper and lower extremes of the ranges reported for T- and M-catalases, respectively. The A-catalase appeared to be more hydrophobic than M-catalase and did not react with antiserum to a representative sample of this class. The banding patterns of T- and M-catalases seen by polyacrylamide gel electrophoresis (PAGE) were essentially unaffected by the incorporation of sodium dodecyl sulfate (SDS) into the PAGE system, whereas the single band of A-catalase seen by PAGE without SDS resolved into as many as five bands in the presence of SDS; these bands were all of slower mobility than the original band. The banding pattern seen with SDS appeared to be related more to counterion charge effects than to molecular size increases that could be attributed to SDS complexed to the protein. It remains to be determined whether the multiple A-catalase bands reflect different proteins or different SDS micellar complexes of a single protein.

Ammonium Sulfate↗
PubMed1995

Biochemical and genetic analyses of a catalase from the anaerobic bacterium Bacteroides fragilis.

A single catalase enzyme was produced by the anaerobic bacterium Bacteroides fragilis when cultures at late log phase were shifted to aerobic conditions. In anaerobic conditions, catalase activity was detected in stationary-phase cultures, indicating that not only oxygen exposure but also starvation may affect the production of this antioxidant enzyme. The purified enzyme showed a peroxidatic activity when pyrogallol was used as an electron donor. It is a hemoprotein containing one heme molecule per holomer and has an estimated molecular weight of 124,000 to 130,000. The catalase gene was cloned by screening a B. fragilis library for complementation of catalase activity in an Escherichia coli catalase mutant (katE katG) strain. The cloned gene, designated katB, encoded a catalase enzyme with electrophoretic mobility identical to that of the purified protein from the B. fragilis parental strain. The nucleotide sequence of katB revealed a 1,461-bp open reading frame for a protein with 486 amino acids and a predicted molecular weight of 55,905. This result was very close to the 60,000 Da determined by denaturing sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified catalase and indicates that the native enzyme is composed of two identical subunits. The N-terminal amino acid sequence of the purified catalase obtained by Edman degradation confirmed that it is a product of katB. The amino acid sequence of KatB showed high similarity to Haemophilus influenzae HktE (71.6% identity, 66% nucleotide identity), as well as to gram-positive bacterial and mammalian catalases. No similarities to bacterial catalase-peroxidase-type enzymes were found. The active-site residues, proximal and distal hemebinding ligands, and NADPH-binding residues of the bovine liver catalase-type enzyme were highly conserved in B. fragilis KatB.

Amino Acid Sequence↗
PubMed1997

Two divergent catalase genes are differentially regulated during Aspergillus nidulans development and oxidative stress.

Catalases are ubiquitous hydrogen peroxide-detoxifying enzymes that are central to the cellular antioxidant response. Of two catalase activities detected in the fungus Aspergillus nidulans, the catA gene encodes the spore-specific catalase A (CatA). Here we characterize a second catalase gene, identified after probing a genomic library with catA, and demonstrate that it encodes catalase B. This gene, designated catB, predicts a 721-amino-acid polypeptide (CatB) showing 78% identity to an Aspergillus fumigatus catalase and 61% identity to Aspergillus niger CatR. Notably, similar levels of identity are found when comparing CatB to Escherichia coli catalase HPII (43%), A. nidulans CatA (40%), and the predicted peptide of a presumed catA homolog from A. fumigatus (38%). In contrast, the last two peptides share a 79% identity. The catalase B activity was barely detectable in asexual spores (conidia), disappeared after germination, and started to accumulate 10 h after spore inoculation, throughout growth and conidiation. The catB mRNA was absent from conidia, and its accumulation correlated with catalase activity, suggesting that catB expression is regulated at the transcription level. In contrast, the high CatA activity found in spores was lost gradually during germination and growth. In addition to its developmental regulation, CatB was induced by H2O2, heat shock, paraquat, or uric acid catabolism but not by osmotic stress. This pattern of regulation and the protective role against H2O2 offered by CatA and CatB, at different stages of the A. nidulans life cycle, suggest that catalase gene redundancy performs the function of satisfying catalase demand at the two different stages of metabolic and genetic regulation represented by growing hyphae versus spores. Alternative H2O2 detoxification pathways in A. nidulans were indicated by the fact that catA/catB double mutants were able to grow in substrates whose catabolism generates H2O2.

Amino Acid Sequence↗
PubMed2001

Multiple catalase genes are differentially regulated in Aspergillus nidulans.

Detoxification of hydrogen peroxide is a fundamental aspect of the cellular antioxidant responses in which catalases play a major role. Two differentially regulated catalase genes, catA and catB, have been studied in Aspergillus nidulans. Here we have characterized a third catalase gene, designated catC, which predicts a 475-amino-acid polypeptide containing a peroxisome-targeting signal. With a molecular mass of 54 kDa, CatC shows high similarity to other small-subunit monofunctional catalases and is most closely related to catalases from other fungi, Archaea, and animals. In contrast, the CatA (approximately 84 kDa) and CatB (approximately 79 kDa) enzymes belong to a family of large-subunit catalases, constituting a unique fungal and bacterial group. The catC gene displayed a relatively constant pattern of expression, not being induced by oxidative or other types of stress. Targeted disruption of catC eliminated a constitutive catalase activity not detected previously in zymogram gels. However, a catalase activity detected in catA catB mutant strains during late stationary phase was still present in catC and catABC null mutants, thus demonstrating the presence of a fourth catalase, here named catalase D (CatD). Neither catC nor catABC triple mutants showed any developmental defect, and both mutants grew as well as wild-type strains in H(2)O(2)-generating substrates, such as fatty acids, and/or purines as the sole carbon and nitrogen sources, respectively. CatD activity was induced during late stationary phase by glucose starvation, high temperature, and, to a lesser extent, H(2)O(2) treatment. The existence of at least four differentially regulated catalases indicates a large and regulated capability for H(2)O(2) detoxification in filamentous fungi.

Amino Acid Sequence↗
PubMed1983

Isolation of the catalase T structural gene of Saccharomyces cerevisiae by functional complementation.

The catalase T structural gene of Saccharomyces cerevisiae was cloned by functional complementation of a mutation causing specific lack of the enzyme (cttl). Catalase T-deficient mutants were obtained by UV mutagenesis of an S. cerevisiae strain bearing the cas1 mutation, which causes insensitivity of catalase T to glucose repression. Since the second catalase protein of S. cerevisiae, catalase A, is completely repressed on 10% glucose, catalase T-deficient mutant colonies could be detected under such conditions. A cttl mutant was transformed with an S. cerevisiae gene library in plasmid YEp13. Among the catalase T-positive clones, four contained overlapping DNA fragments according to restriction analysis. Hybridization selection of yeast mRNA binding specifically to one of the cloned DNAs, translation of this mRNA in cell-free protein synthesis systems, and demonstration of catalase T protein formation by specific immunoadsorption showed that the catalase T structural gene had been cloned. By subcloning, the gene was located within a 3.5-kilobase S. cerevisiae DNA fragment. As in wild-type cells, catalase T synthesis in cttl mutant cells transformed with plasmids containing this fragment is sensitive to glucose repression. By DNA-RNA hybridization, catalase T transcripts were shown to be present in oxygen-adapting cells but absent from heme-deficient cells.

Catalase↗
PubMed1983

Properties of a catalase from a peroxide-resistant mutant of Proteus mirabilis.

A catalase (EC 1.11.1.6) from Proteus mirabilis PR, a mutant with strong resistance to hydrogen peroxide, was purified to homogeneity and compared with catalase from wild-type P. mirabilis. In crude extracts from the mutant, catalase was present as two different entities called A and B, that could be resolved by ion-exchange chromatography. The B form was transformed into A. The pure catalase preparation contained the A form only. This catalase was not found to be different from the wild-type enzyme, considering its molecular weight, subunit composition, isoelectric pH, and reactivity to specific antibodies. Partial proteolytic cleavage of the two bacterial enzymes with four different proteases proceeded at the same rate and produced identical patterns. However, pure catalase from the mutant had a specific activity against H2O2 of 2.7 X 10(7) M-1 X s-1, and its purity index (A406/A280) was 1.12. These values were higher than previously determined for the wild-type enzyme. Furthermore, the mutant catalase was more stable to heat. The results suggest that the purified catalase (A form) differs from the wild-type enzyme and appears to be a more efficient catalase against H2O2. Both enzymes were found to be much more resistant than beef liver catalase to the classically used catalase inhibitor 3-amino-1,2,4-triazole.

Amitrole↗
PubMed1998

Immunotargeting of catalase to ACE or ICAM-1 protects perfused rat lungs against oxidative stress.

The pulmonary endothelium is susceptible to oxidative insults. Catalase conjugated with monoclonal antibodies (MAbs) against endothelial surface antigens, angiotensin-converting enzyme (MAb 9B9) or intercellular adhesion molecule-1 (MAb 1A29), accumulates in the lungs after systemic injection in rats (V. Muzykantov, E. Atochina, H. Ischiropoulos, S. Danilov, and A. Fisher. Proc. Natl. Acad. Sci. USA 93: 5213-5218, 1996). The present study characterizes the augmentation of antioxidant defense by these antibody-catalase conjugates in isolated rat lungs perfused for 1 h with catalase conjugated with either MAb 9B9, MAb 1A29, or control mouse IgG. Approximately 20% of the injected dose of Ab-125I-catalase accumulated in the perfused rat lungs (vs. <5% for IgG-125I-catalase). After elimination of nonbound material, the lungs were perfused further for 1 h with 5 mM hydrogen peroxide (H2O2). H2O2 induced an elevation in tracheal and pulmonary arterial pressures (126 +/- 7 and 132 +/- 5%, respectively, of the control level), lung wet-to-dry weight ratio (7.1 +/- 0.4 vs. 6.0 +/- 0.01 in the control lungs), and ACE release into the perfusate (436 +/- 20 vs. 75 +/- 7 mU in the control perfusates). Both MAb 9B9-catalase and MAb 1A29-catalase significantly attenuated the H2O2-induced elevation in 1) angiotensin-converting enzyme release to the perfusate (215 +/- 14 and 217 +/- 38 mU, respectively), 2) lung wet-to-dry ratio (6.25 +/- 0.1 and 6.3 +/- 0.3, respectively), 3) tracheal pressure (94 +/- 4 and 101 +/- 4%, respectively, of the control level), and 4) pulmonary arterial pressure (103 +/- 3 and 104 +/- 7%, respectively, of the control level). Nonconjugated catalase, nonconjugated antibodies, nonspecific IgG, and IgG-catalase conjugate had no protective effect, thus confirming the specificity of the effect of MAb-catalase. These results support a strategy of catalase immunotargeting for protection against pulmonary oxidative injury.

Animals↗
PubMed1984

Protection against oxygen toxicity by intravenous injection of liposome-entrapped catalase and superoxide dismutase.

Survival of rats exposed to 100% oxygen was increased from 69.5 +/- 1.5 to 118.1 +/- 9.9 h (mean +/- SEM, P less than 0.05) when liposomes containing catalase and superoxide dismutase were injected intravenously before and during exposure. The increased survival time in 100% oxygen was also associated with significantly less fluid in the pleural cavity. Rats injected with catalase- and superoxide dismutase-containing liposomes, which had increased survival in 100% oxygen, had increased lung wet weight upon autopsy compared with saline-injected controls (2.9 +/- 0.2 g/lung vs. 4.8 +/- 0.4 g/lung, mean +/- SE, P less than 0.05). Intravenous injection of control liposomes along with catalase and superoxide dismutase in the suspending buffer decreased the mean pleural effusion volume 89% and had no significant effect on survival time. Lung catalase and superoxide dismutase activities were increased 3.1- and 1.7-fold, respectively, 2 h after a single intravenous injection of liposomes containing catalase or superoxide dismutase. Superoxide dismutase activity was also significantly greater than controls in both air- and 100% oxygen-exposed rat lungs, when enzyme activity was assayed 24 h after cessation of injection of control and oxygen-exposed rats with enzyme-containing liposomes every 12 h for 36 h. Free superoxide dismutase and catalase injected intravenously in the absence of liposomes did not increase corresponding lung enzyme activities, affect pleural effusion volume, lung wet weight, or extend the mean survival time of rats exposed to 100% oxygen. The clearance of liposome-augmented 125I-labeled catalase from lung and plasma obeyed first order kinetics according to a one-compartment model. When clearance of liposome-augmented catalase activity or radioactivity were the parameters used for pharmacokinetic studies, the half-life of augmented lung catalase was 1.9 and 2.6 h, respectively. The half-life of liposome-entrapped catalase and superoxide dismutase activity in the circulation was 2.5 and 4 h, respectively, while intravenously injected catalase and superoxide dismutase had a circulation half-life of 23 and 6 min, respectively.

Animals↗
PubMed1976

Localization of catalase A in vacuoles of Saccharomyces cerevisiae: evidence for the vacuolar nature of isolated "yeast peroxisomes".

The subcellular distribution of catalase A in the yeast Saccharomyces cerevisiae has been investigated. The enzyme was found to be bound to large particles, whereas most of the activity of catalase T was located in a 38 000 X g supernatant. Under various isolation conditions catalase A always showed a distribution among subcellular fractions virtually identical to that of two markers for vacuoles, proteinase B and alpha-mannosidase. More than 80 percent of the catalase A activity of a crude vacuole fraci-onercent of the catalase A activity of a crude vacuole fraction has been detected in purified vacuoles. Malate synthase, isocitrate lyase and glyoxylate reductase (NADP), three peroxisomal markers, showed a subcellular distribution significantly different from that of catalase A. It is concluded from these results that catalase A is specifically associated with the vacuoles of yeast. Like vacuoles, "peroxisomal" fractions isolated from yeast spheroplasts as described by Avers[1] contain only one catalase protein, catalase A. It could be shown by isopycnic and sedimentation velocity separations of crude mitochondrial fractions that catalase A in "peroxisomal" fractions is accompanied by considerable activities of proteinase B and alpha-mannosidase. From all our results it seems that the catalase-active particles isolated under such conditions are not typical peroxisomes but vesicles formed from vacuoles during the isolation procedure.

Animals↗