Purification and characterization of catalase from goat (Capra capra) lung

Purification and biochemical characterization of catalase that confers protection against hydrogen peroxide induced by stressful desert environment: the Camelus Dromedarius kidney catalase

Camel is continually exposed to stressful desert environment that enhances generation of reactive oxygen species, including hydrogen peroxide (H₂O₂). Catalase plays an important role in detoxification of H₂O₂. A highly active catalase from camel kidney was purified to homogeneity, with a specific activity of 1,774,392 U/mg protein, using ion exchange and metal chelate affinity chromatography. The molecular weight of the enzyme was 268 kDa consisting of four identical subunits of 63 kDa. The enzyme showed higher optimum temperature (45 °C) and higher activation energy (4.37 kJ mol^-1). The thermodynamic parameters, ΔH, ΔG and ΔS, were determined. The effect of various metal ions and chemicals on enzyme activity was investigated. K_m, V_max, k_cat and k_cat/K_m values for H₂O₂ were found to be 46 mM, 10,715,045 U/mg, 48,265,968 s^-1 and 2,966,562 s^-1mM^-1, respectively. Camel kidney catalase displayed higher affinity efficiency for H₂O₂ and can protect reduced glutathione (GSH) from oxidation by H₂O₂. Sodium azide was found to be a noncompetitive inhibitor of enzyme with K_i and IC₅₀ of 17.88 µM and 20.94 µM, respectively. Camel catalase showed unique biochemical properties. Interestingly, camel catalase can protect molecules (GSH) and organ functions (kidney) from the toxic effects of H₂O₂ induced by stressful desert environment.

Soluble epoxide hydrolase contamination of specific catalase preparations inhibits epoxyeicosatrienoic acid vasodilation of rat renal arterioles

Cytochrome P-450 metabolites of arachidonic acid, the epoxyeicosatrienoic acids (EETs) and hydrogen peroxide (H(2)O(2)), are important signaling molecules in the kidney. In renal arteries, EETs cause vasodilation whereas H(2)O(2) causes vasoconstriction. To determine the physiological contribution of H(2)O(2), catalase is used to inactivate H(2)O(2). However, the consequence of catalase action on EET vascular activity has not been determined. In rat renal afferent arterioles, 14,15-EET caused concentration-related dilations that were inhibited by Sigma bovine liver (SBL) catalase (1,000 U/ml) but not Calbiochem bovine liver (CBL) catalase (1,000 U/ml). SBL catalase inhibition was reversed by the soluble epoxide hydrolase (sEH) inhibitor tAUCB (1 μM). In 14,15-EET incubations, SBL catalase caused a concentration-related increase in a polar metabolite. Using mass spectrometry, the metabolite was identified as 14,15-dihydroxyeicosatrienoic acid (14,15-DHET), the inactive sEH metabolite. 14,15-EET hydrolysis was not altered by the catalase inhibitor 3-amino-1,2,4-triazole (3-ATZ; 10-50 mM), but was abolished by the sEH inhibitor BIRD-0826 (1-10 μM). SBL catalase EET hydrolysis showed a regioisomer preference with greatest hydrolysis of 14,15-EET followed by 11,12-, 8,9- and 5,6-EET (V(max) = 0.54 ± 0.07, 0.23 ± 0.06, 0.18 ± 0.01 and 0.08 ± 0.02 ng DHET·U catalase(-1)·min(-1), respectively). Of five different catalase preparations assayed, EET hydrolysis was observed with two Sigma liver catalases. These preparations had low specific catalase activity and positive sEH expression. Mass spectrometric analysis of the SBL catalase identified peptide fragments matching bovine sEH. Collectively, these data indicate that catalase does not affect EET-mediated dilation of renal arterioles. However, some commercial catalase preparations are contaminated with sEH, and these contaminated preparations diminish the biological activity of H(2)O(2) and EETs.

Aspirin May Exert Its Antipyresis by Inhibiting the N-Methyl-D-aspartate Receptor-Dependent Hydroxyl Radical Pathways in the Hypothalamus

Recent findings have suggested that the N-methyl-D-aspartate (NMDA) receptor-dependent hydroxyl radical pathway in the hypothalamus of rabbit brain may mediate the fever induced by lipopolysaccharide (LPS). The aim of this study was to investigate whether aspirin exerts its antipyresis by suppressing hypothalamic glutamate and hydroxyl radicals in rabbits. The microdialysis probes were stereotaxically and chronically implanted into the preoptic anterior hypothalamus of rabbit brain for determination of both glutamate and hydroxyl radicals in situ. It was found that intravenous (i.v.) injection of LPS, in addition to inducing fever, caused increased levels of both glutamate and hydroxyl radicals in the hypothalamus. Pretreatment with aspirin (10 - 60 mg/kg, i.v.) one hour before an i.v. dose of LPS significantly reduced the febrile response and attenuated the LPS-induced increased levels of both glutamate and hydroxyl radicals in the hypothalamus. The increased levels of prostaglandin E(2) (PGE(2)) in the hypothalamus induced by LPS could be suppressed by aspirin pretreatment. The data indicate that systemic administration of aspirin, in addition to suppressing PGE(2) production, may exert its antipyresis by inhibiting the NMDA receptor-dependent hydroxyl radical pathways in the hypothalamus during LPS fever.

Expression, purification, and sequence analysis of catalase-1 from the soil bacterium Comamonas terrigena N3H

Catalases are essential components of the cellular equipment to cope with oxidative stress. We have purified and characterize herein the most abundant heme-containing catalase-1 from the soil bacterium Comamonas terrigena N3H. This oxidative stress-induced enzyme was isolated from exponential phase cells grown in the presence of peroxyacetic acid. We have used consecutive steps of hydrophobic, molecular sieve, and ion exchange chromatography to achieve a high state of purity for this metalloenzyme. The purified sample of catalase exhibited a specific catalytic activity of 55,900 U/mg, allosteric behavior in peroxidic reaction, a broad pH optimum, and a rather atypical electronic spectrum. The sample of highest purity was subjected to mass spectrometry analysis. The molecular weight of the subunit of this homodimeric protein was determined as 55,417 Da. The Qq-TOF mass analysis method allowed us to sequence short tryptic fragments of this catalase. Five such fragments with a total length of 57 amino acids together with several enzymatic properties allowed the classification of this hydroperoxidase as belonging to clade III of monofunctional catalases. The highest sequence similarity is with the catalase from Vibrio fischeri. The presented results imply the significance of this inducible enzyme in the prevention of toxic effects of oxidative stress for bacterial cells.

Inhibition of oxygen radical formation by methylene blue, aspirin, or alpha-lipoic acid, prevents bacterial-lipopolysaccharide-induced fever

Phagocytic cells contain NADPH oxidase that they use for host defense by catalyzing the production of superoxide. Bacterial lipopolysaccharide (LPS) has been found to stimulate NADPH oxidase in mobile and sessile macrophages and microglia. It also evokes fever in homeothermic animals and men, a reaction mediated by central nervous system (CNS) activities. The purpose of the present study was to determine whether reactive oxygen species are involved in LPS-induced fever. In rabbits we found that plasma hydroperoxide levels increased and catalase activity decreased 15 min after LPS injection and that fever started with a similar latency, while plasma levels of tumor necrosis factor-alpha (TNFalpha) increased 30 min after the injection. Treating rabbits with methylene blue or aspirin did not affect TNFalpha secretion but prevented the LPS-induced rise of hydroperoxides and the inactivation of catalase, abolishing fever. Incubation of human blood with nitroblue tetrazolium and LPS increased the number of formazan-positive neutrophils from 10 +/- 5 to 52 +/- 9%. Adding LPS to blood preincubated with either methylene blue, alpha-lipoic acid, or aspirin respectively decreased the number of formazan-positive neutrophils to 0.9 +/- 0.8, 0.8 +/- 0.9, or 2.0 +/- 0.9%, disclosing the antioxidant capacity of these drugs. Systemic application of 80 mg/kg alpha-lipoic acid elicited heat-loss reactions within 15 min and decreased core temperature by 2.2 +/- 0.3 degrees C within 2 h. Alpha-lipoic acid applied 45 min after LPS induced antipyresis within 15 min, and this antipyresis was associated with a decrease of elevated hydroperoxide levels and restoration of catalase activity. Our results show that fever is prevented when the production of reactive oxygen species is blocked and that an elevated body temperature returns to normal when oxygen radical production decreases. Estimation of plasma dihydrolipoic acid (DHLA) levels following injection of 80 mg/kg alpha-lipoic acid in afebrile and febrile rabbits revealed that this acid is converted into DHLA, which in afebrile rabbits increased the plasma DHLA concentration from 2.22 +/- 0.26 microg/ml to peak values of 8.60 +/- 2.28 microg/ml DHLA within 30 min and which in febrile rabbits increased it from 0.84 +/- 0.22 microg/ml to peak values of 3.90 +/- 0.94 microg/ml within 15 min. Methylene blue, aspirin, and alpha-lipoic acid, which all cross the blood-brain barrier, seem to act not only on peripheral tissues but also on the CNS. Brain structures that have been shown to sense oxidative stress are vicinal thiol groups attached to the NMDA subtype of glutamate receptor. Their reduction by thiol-reducing drugs like dithiothreitol or DHLA has been found to increase glutamate-mediated neuronal excitability, while the opposite effect has been observed after their oxidation. Because we found that systemic application of alpha-lipoic acid in the afebrile state elicits hypothermia and in the febrile state is antipyretic, we think this type of NMDA receptor is involved in thermoregulation and that oxidation of its thiol groups induces fever. It appears that temperature homeostasis can be maintained only if the redox homeostasis of the brain is guaranteed.