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Fusion of complementary cell lines from patients with diseases of peroxisome biogenesis leads to peroxisome assembly in the heterokaryons and to uptake of cytosolic catalase by the newly assembled peroxisomes. Here we show that catalase import is inhibited by prior binding to catalase of the inhibitor 3-amino-1,2,4-triazole, which appears to retard unfolding of the protein.
The methylotrophic yeast, Hansenula polymorpha, harbours a unique catalase (EC 1.11.1.6), which is essential for growth on methanol as a carbon source and is located in peroxisomes. Its corresponding gene has been cloned and the nucleotide sequence determined. The deduced amino acid sequence displayed the tripeptide serine-lysine-isoleucine at the extreme C-terminus, which is similar to sequences of other peroxisomal targeting signals. Exchange of the ultimate amino acid, isoleucine, of catalase for serine revealed a cytosolic enzyme activity and a concomitant loss of peroxisome function. We concluded that the tripeptide is essential for targeting of catalase in H. polymorpha.
Catalase-bound NADPH both prevents and reverses the accumulation of inactive bovine liver catalase peroxide compound II generated by 'endogenous' donors under conditions of steady H2O2 formation without reacting rapidly with either compound I or compound II. It thus differs both from classical 2-electron donors of the ethanol type, and from 1-electron donors of the ferrocyanide/phenol type. NADPH also inhibits compound II formation induced by the exogenous one-electron donor ferrocyanide. A catalase reaction scheme is proposed in which the initial formation of compound II from compound I involves production of a neighbouring radical species. NADPH blocks the final formation of stable compound II by reacting as a 2-electron donor to compound II and to this free radical. The proposed behaviour resembles that of labile free radicals formed in cytochrome c peroxidase and myoglobin. Such radical migration patterns within haem enzymes are increasingly common motifs.
It was demonstrated that salicylic acid (SA) not only binds to catalase from differentiated higher plants and plant cell suspension cultures but also to those of fungi and animals. SA bound specifically to iron-containing enzymes, such as catalase, aconitase, lipoxidase and peroxidase, while not to iron-free plant enzymes. On the grounds of these experiments, the claim is further challenged that SA is a signalling compound and second messenger in plants that activates plant defense-related genes through elevated H2O2 levels by specifically inhibiting catalase activity. SA may just function as a phytoalexin.
The three-dimensional structure analysis of crystalline fungal catalase from Penicillium vitale has been extended to 2.0 A resolution. The crystals belong to space group P3(1)21, with the unit cell parameters of a = b = 144.4 A and c = 133.8 A. The asymmetric unit contains half a tetrameric molecule of 222 symmetry. Each subunit is a single polypeptide chain of approximately 670 amino acid residues and binds one heme group. The amino acid sequence has been tentatively determined by computer graphics model building (using the FRODO system) and comparison with the known sequence of beef liver catalase. The atomic model has been refined by the Hendrickson & Konnert (1981) restrained least-squares program against 68,000 reflections between 5 A and 2 A resolution. The final R-factor is 0.31 after 24 refinement cycles. The secondary and tertiary structure of the catalase has been analyzed.
Our previous studies have demonstrated a decreased glutathione feroxidase (GSH-Px) activity of erythrocytes and leucocytes from multiple sclerosis (MS) patients. In the present communication these activities were compared with the activities of associated enzymes (glutathione reductase (GSSG-RD), glucose-6-phosphate dehydrogenase (G-6-PD) and catalase). All enzymic activities were compared between MS patients, other neurologic patients (ON patients) and normal control individuals. Compared to data of ON patients and normal controls, in MS the ratio of GSHPx/GSSGRD in lympho- and granulocytes was significantly decreased (2 alpha less than or equal to 0.05) by 35% and 51%, respectively. The significant correlation between GSSG-RD and the GSH-Px activity (2 alpha less than or equal to 0.05, r = 0.501) found in control lymphocytes was not present in MS lymphocytes. However, the lymphocyte GSH-Px activities of controls as well as of MS correlated with the corresponding serum selenium levels (2 alpha less than or equal to 0.05, r = 0.594 and 2 alpha less than or equal to 0.01, r = 0.967, respectively). The G-6-PD activity was insignificantly increased by 41% in MS lymphocytes compared to normal control. Catalase activity was unchanged in lymphocytes but decreased 50% in MS granulocytes compared to normal control. No significant differences were found between MS and the ON group. The catalase activity of MS erythrocytes was increased by 63% (2 alpha less than or equal to 0.05) in comparison with both the normal control and ON data.
The activity and a few properties of catalase have been compared in the developing human placenta and fetal liver. The presence of the enzyme in both the tissues is discernible as early as in the 6th wk of gestation and the activity increases gradually with the advancement of pregnancy. Maximum enzyme activity in both placenta and fetal liver is found to be associated with the soluble supernatant fraction obtained by centrifuging the tissue homogenates at 105000 X g. Kinetic studies reveal the enzymatic decomposition of H2O2 to follow first-order kinetics at lower substrate concentrations, and then to deviate from the original linearity, demonstrating mixed-order kinetics. Thermostability of placental catalase increases with prenatal development, while the enzyme from fetal liver remains moderately heat-stable throughout the gestation. Treatment of the homogenates with Triton X-100 is found to be most effective in increasing catalase activity in each of these tissues.
The effects of the catalase inhibitor, 3-amino-1,2,4-triazole (AT), on maintenance of voluntary consumption of ethanol was tested in male Long-Evans rats. AT produced a dose-dependent reduction in ethanol intake but did not affect total fluid consumption. AT also produced a dose-dependent inhibition of brain catalase lasting throughout the drinking period. These results suggest a role for brain catalase in determining the level of ethanol intake in rats.
Hydrogen peroxide in contact with the oral mucosa induces vesicle formation and ulceration. This study assesses the protective effect of catalase against the hydrogen peroxide insult in the rat tongue mucosa. In addition, we report a detailed histologic characterization of the mucosal injury. Four repetitive applications of 30% hydrogen peroxide at 15 minute intervals produced a vast edema of the submucosal tissue including the tongue muscles that was seen immediately after the last application. Histomorphometric measurements indicated a substantial regression of the edema 1 day later with the appearance of a very large ulceration lined by a pyogenic membrane. Animals examined 7 days after the hydrogen peroxide administration revealed almost complete healing in terms of absence of edema and renewal of intact epithelial lining. Catalase applied to the tongue before the hydrogen peroxide fully prevented the pathologic tissue reaction. Thus testing of the clinical feasibility of catalase in protecting the oral mucosa against hydrogen peroxide-induced injury is strongly indicated.
Crithidia fasciculata, which contains high levels of a cytosolic catalase, is sensitive to inhibition by at least two nitroheterocyclic drugs, Nifurtimox and MK 436, both of which are also active against Trypanosoma cruzi. Drug sensitivity is not enhanced in organisms containing reduced levels of catalase. The ultrastructural lesions in T. cruzi produced by nitroheterocycles, especially the swelling and gross vacuolation of the mitochondria, are seen also in C. fasciculata. These results are not consistent with the hypothesis that the action of drugs such as Nifurtimox on T. cruzi involve hydrogen peroxide accumulation as a result of the absence of catalase.
Glutathione peroxidase (GPX), superoxide dismutase (SOD) and catalase are the most important enzymes of the cell antioxidant defense system. However, these molecules are themselves susceptible to oxidation. The aim of this work was to estimate to what extent this system could be inactivated by its own substrates. We tested the effect of hydrogen peroxide, cumene hydroperoxide, t-butyl hydroperoxide and hydroxyl and superoxide radicals on GPX, SOD and catalase. For GPX, a 50% inactivation was observed at 10(-1) M (30 min, 37 degrees C) for hydrogen peroxide, 3 x 10(-4) M (15 min, 37 degrees C) for cumene hydroperoxide and 5 x 10(-5) M (11 min, 37 degrees C) for t-butyl hydroperoxide. Unlike the hydroxyl radicals, superoxide anions did not inactivate this enzyme. Catalase was inactivated by hydroxyl radicals and by superoxide anions but organic peroxides had no effect. SOD was inactivated by 50% by hydrogen peroxide at 4 x 10(-4) M (20 min, 37 degrees C), but organic peroxides and hydroxyl radicals were ineffective on this enzyme. Since the three enzymes of the antioxidant system are susceptible to at least one of the oxidative reactive molecules, in the case of high oxidative stresses such an inhibition could take place, leading to an irreversible autocatalytical process in which the production rate of the oxidants will continuously increase, leading to cell death.
Calorimetric studies of the effect of superoxide dismutase and/or catalase on the reduction of dioxygen into water by dithionite in oxyhemoglobin have been carried out and the results compared with those in red cell hemolysates. In the absence of the enzymes the stoichiometry (moles dithionite/mole dioxygen) is less than the value of 2:1 which was found previously in red cell hemolysates [Forlani et al., J. Inorg. Biochem. 20, 147-155 (1984)]. In the presence of either superoxide dismutase or catalase alone the stoichiometry increases but is still less than 2:1. In the presence of both enzymes the stoichiometry and the shape of the thermogram is that previously observed for hemolysates, suggesting the presence of a hemoglobin-catalase-superoxide dismutase integrated system. The absence of a calorimetric signal for hydrogen peroxide in the reduction of oxyhemoglobin in the presence of superoxide dismutase suggests a wider biological role of superoxide dismutase than previously thought.
Catalase activity and cytochrome content were measured in kidneys of Fisher 344 rats injected with aurothioglucose (ATG) either daily for 3 days or 5 days a week for up to 8 wk. Catalase activity was decreased 39%, 59%, and 48% (all p less than 0.001) after 3 days, 2 wk, and 8 wk, respectively. Microsomal cytochrome P-450 levels decreased 71%, 86%, and 80% (all p less than 0.001) after 3 days, 2 wk, and 8 wk, respectively. In contrast, cytochrome b5 was significantly increased at 3 days and 2 wk, but not at 8 wk. Microsomal heme contents decreased 44% (p less than 0.001), 34% (p less than 0.001), and 22% (p greater than 0.05) at 3 days, 2 wk, and 8 wk, respectively. The content of mitochondrial cytochromes aa3, b, c1, and c were not affected after 8 wk of ATG treatment. In vitro inhibition of the heme-containing enzyme delta-aminolevulinic acid dehydratase by ATG was reversible in the presence of physiological concentrations of small thiols. Although the activity of this enzyme in kidneys of ATG-treated rats was not measured, its significant inhibition in vivo by ATG appears unlikely. This study demonstrates that there were differential effects of gold on the various cytochromes and that changes in catalase activity paralleled changes in cytochrome P-450 and heme contents in the kidneys of ATG-treated rats. The findings are relevant to nephrotoxicity during chrysotherapy.
The magnetic circular dichroism (MCD) spectra of three horse heart metmyoglobin compounds, the cyanide, azide and hydroxide forms, have been measured in the visible and near infrared spectral regions at temperatures down to 1.5 K. The three compounds are all virtually completely low-spin at low temperatures with ground g factors of decreasing rhombicity in the order CN- greater than N3- greater than OH-. The MCD magnetization curves have been constructed at selected wavelengths throughout the visible and near infrared regions. The curves are independent of wavelength, showing that all the bands studied are x,y polarized and can, moreover, be satisfactorily fitted to the g factors determined by EPR spectroscopy with theoretical expressions (Thomson, A.J. and Johnson, M.K. (1980) Biochem. J. 191, 411-420). This confirms the assignment and polarizations of the near infrared region low-spin ferric haem charge-transfer bands. The energies of these transitions are markedly dependent upon the added axial ligand, ranging from 1595 to 1295, and 1050 nm for the compounds CN-, N3- and OH-. The MCD spectra of bovine liver catalase and its cyanide adduct have been recorded in the Soret, visible and near infrared regions. Catalase is know to have phenolate anion as the proximal ligand of the haem group. The forms of the spectra make an interesting comparison with those of the analogous metmyoglobin derivatives, in which histidine is the proximal ligand. The MCD spectra of catalase at 4.2 K is an example of a fully high-spin haemoprotein. The cyanide compound is completely low-spin at 4.2 K. The near infrared charge-transfer band is at 1300 nm, showing the effect on the energy of this band of changing from imidazole to phenolate ion as the proximal ligand to haem.
Bovine liver catalase (hydrogen-peroxide:hydrogen peroxide oxidoreductase, EC 1.11.1.6) was derivatized by 9"(10")-[4'-(2-(4,6-dichloro-1,3,5-triazinyl) oxy)butoxy] stearic acid and the fatty acyl-coated enzyme was separated from native catalase and excess reagent by hydroxyapatite chromatography. The derivatization of catalase resulted in coupling the long-chain fatty acyl residues to lysine, histidine and arginine, while other amino acids remained essentially unaffected. The fatty acyl-coated enzyme was water soluble at pH greater than 7.0 but became octanol and ether soluble at pH less than 6.5. The derivatized enzyme retained 50-80% of the catalatic- and peroxidative-specific activities. The free carboxyl function of the coupled long-chain fattyl acyl residues could serve as substrate for ATP-dependent CoA-thioesterification catalyzed by the rat liver microsomal long-chain fatty acyl-CoA synthase.
The effect of vasoactive intestinal peptide (VIP) on the activities of superoxide dismutase and catalase was investigated in renal tissues of rats exposed to 30% hemorrhage followed by reperfusion. In addition to enzyme activities, renal tissues were also histologically evaluated. Thirty percent hemorrhage had no significant effect on the activity of either enzyme. Reperfusion altered the activity of renal catalase but not of superoxide dismutase. On the other hand, administration of VIP (25 ng.kg-1) together with shed blood retransfusion protected the renal tissue from hemorrhagic ischemia-reperfusion injury without increasing superoxide dismutase and catalase activity. These results seem to be related either to the inhibitory effect of VIP on production or quenching activity of some reactive oxygen species. In conclusion, VIP may be a novel promising therapeutic approach toward defenses against hemorrhagic ischemia-reperfusion injury as an antioxidant.
The effects of scald injury and scald injury with pretreatment on plasma and water content were studied in the superfused hamster cheek pouch. Catalase (30,000 Units/kg), indomethacin (2.5 mg/kg) and FPL 55712 (2 mg/kg) were administered prior to 10 second scald with 100 degrees C normal saline. Plasma content was measured with 125 I serum albumin and water content was calculated by loss on drying. Significant (P less than 0.05) decreases in plasma content compared to scald alone were observed following pretreatment with catalase (29%) indomethacin (31%) or FPL 55712 (52%). Water content in scalded pouches was significantly reduced by catalase (29%) and FPL 55712 (42%). Pretreatment when combined also resulted in significant reduction of plasma content but not water content. Results suggest that free-radicals, prostaglandins and leukotrienes are involved in vascular response by scald injury.
Ochratoxin A (OTA) is a mycotoxin produced by Aspergillus ochraceus as well as other molds. It is a natural contaminant of mouldy food and feed. OTA has a number of toxic effects, the most prominent being nephrotoxicity. Furthermore, OTA is immunosuppressive, genotoxic, teratogenic and carcinogenic. OTA inhibits protein synthesis by competition with phenylalanine in the phenylalanine-tRNA aminoacylation reaction. Recently, lipid peroxidation induced by OTA has been reported, indicating that the lesions induced by this mycotoxin could be also related to oxidative pathways. It was then interesting to study effects of the superoxide dismutase (SOD) and catalase on the nephrotoxicity induced by OTA in rats. The two enzymes (20 mg/kg body weight each) were given to rats by subcutaneous injection, every 48 h, 1 h before gavage by OTA (289 micrograms/kg b.w. every 48 h), for 3 weeks. SOD and catalase prevented most of the nephrotoxic effects induced by ochratoxin A, observed as enzymuria, proteinuria, creatinemia and increased urinary excretion of OTA. Altogether these results indicate (i) that superoxide radicals and hydrogen peroxide are likely to be involved in the damaging processes of OTA in vivo, (ii) that SOD and catalase might be used for prevention of renal lesions in cases of ochratoxicosis.