Purification and characterization of liver catalase in acatalasemic beagle dog: comparison with normal dog liver catalase

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.

Effects of a Diet Supplemented with Exogenous Catalase from Penicillium notatum on Intestinal Development and Microbiota in Weaned Piglets

This study aims to investigate the effects of exogenous catalase (CAT), an antioxidative enzyme from microbial cultures, on intestinal development and microbiota in weaned piglets. Seventy-two weaned piglets were allotted to two groups and fed a basal diet or a basal diet containing 2.0 g/kg exogenous CAT. Results showed that exogenous CAT increased (p < 0.05) jejunal villus height/crypt depth ratio and intestinal factors (diamine oxidase and transforming growth factor-α) concentration. Moreover, dietary CAT supplementation enhanced the antioxidative capacity, and decreased the concentration of pro-inflammatory cytokine in the jejunum mucosa. Exogenous CAT did not affect the concentration of short-chain fatty acids, but decreased the pH value in colonic digesta (p < 0.05). Interestingly, the relative abundance of Bifidobacterium and Dialister were increased (p < 0.05), while Streptococcus and Escherichia-Shigella were decreased (p < 0.05) in colonic digesta by exogenous CAT. Accordingly, decreased (p < 0.05) predicted functions related to aerobic respiration were observed in the piglets fed the CAT diet. Our study suggests a synergic response of intestinal development and microbiota to the exogenous CAT, and provides support for the application of CAT purified from microbial cultures in the feed industry.

Effects of dietary supplementation with exogenous catalase on growth performance, oxidative stress, and hepatic apoptosis in weaned piglets challenged with lipopolysaccharide

Two experiments were conducted to investigate the effects of exogenous catalase (CAT) in the diet of weaned piglets on growth performance, oxidative capacity, and hepatic apoptosis after challenge with lipopolysaccharide (LPS). In experiment 1, 72 weaned piglets [Duroc × Landrace × Yorkshire, 6.90 ± 0.01 kg body weight (BW), 21 d of age] were randomly assigned to be fed either a basal diet (CON group) or a basal diet supplemented with 2,000 mg/kg CAT (CAT group; dietary CAT activity, 120 U/kg) for 35 d. Blood samples were collected on day 21 and day 35. At the end of this experiment, 12 pigs were selected from each of the CON and CAT groups, and six pigs were injected with LPS (50 μg/kg BW), while the remaining six pigs were injected with an equal amount of sterile saline, resulting in a 2 × 2 factorial arrangement of treatments (experiment 2). Blood samples and rectal temperature data were collected 0 and 4 h after challenge, and liver samples were obtained after evisceration. The gain-to-feed ratio was higher (P < 0.05) in piglets in the CAT group than in those in the CON group from day 1 to 35. Catalase and total superoxide dismutase (T-SOD) activities were higher (P < 0.05), whereas malondialdehyde (MDA) concentrations were lower (P < 0.05), in piglets in the CAT group than in those in the CON group at day 35. During challenge, rectal temperature and liver MDA and H2O2 concentrations increased significantly (P < 0.05), whereas plasma CAT and glutathione peroxidase (GSH-Px) activities and liver CAT activity decreased markedly (P < 0.05), in LPS-challenged piglets 4 h post-challenge. Increased CAT activity and decreased MDA concentration were observed in the plasma and liver of piglets in the CAT group 4 h post-challenge (P < 0.05). Dietary CAT supplementation markedly suppressed the LPS-induced decrease in plasma GSH-Px activity and liver CAT activity to levels observed in the CON group (P < 0.05) as well as significantly decreasing the concentration and mRNA expression of caspase-3 and caspase-9 (P < 0.05). LPS-induced liver injury was also attenuated by dietary CAT supplementation, as demonstrated by a decrease in liver caspase-3 mRNA expression (P < 0.05). Overall, dietary supplementation with 2,000 mg/kg exogenous CAT (dietary CAT activity, 120 U/kg) improves growth performance and has a beneficial effect on antioxidant capacity in weaned piglets; alleviates oxidative stress and reduces liver damage by suppressing hepatic apoptosis in LPS-challenged piglets.

Catalase from larvae of the camel tick Hyalomma dromedarii

Catalase plays a major role in protecting cells against toxic reactive oxygen species. Here, Catalase was purified from larvae of the camel tick Hyalomma dromedarii and designated TLCAT. It was purified by ammonium sulfate precipitation and chromatography on DEAE-cellulose, Sephacryl S-300 and CM-cellulose columns. Gel filtration and SDS-PAGE of the purified TLCAT indicated that the protein has a native molecular weight of 120 kDa and is most likely a homodimer with a subunit of approximately 60 kDa. The Km value of TLCAT is 12 mM H2O2 and displayed its optimum activity at pH 7.2. CaCl2, MgCl2, MnCl2 and NiCl2 increased the activity of TLCAT, while FeCl2, CoCl2, CuCl2 and ZnCl2 inhibited the activity of TLCAT. Sodium azide inhibited TLCAT competitively with a Ki value of 0.28 mM. The presence of TLCAT in cells may play a role in protecting H. dromedarii ticks against oxidative damage. This finding will contribute to our understanding of the physiology of these ectoparasites and the development of untraditional methods to control them.

Purification and characterization of catalase from sprouted black gram (Vigna mungo) seeds

Black gram (Vigna mungo) is a legume which belongs to Fabaceae family. It is a rich source of protein. It has been known to have interesting small molecule antioxidant activity. However, its enzymatic antioxidant properties have not been explored much. In the present work we studied catalase, a principal antioxidant enzyme from black gram seeds. Day four sprouted black gram seeds were found to have a significant catalase content approximately of 15,240 U/g seeds. IMAC (Seph 4B-IDA-Zn(II)) was used for purifying this catalase, a purification fold of 106 and a high specific activity of 25,704 U/mg was obtained. The K(m) and V(max) of the purified catalase were found to be 16.2 mM and 2.5 μmol/min. The effect of inhibitors like Sodium azide (NaN(3)) and EDTA and different metal ions on catalase activity were studied. NaN(3), Fe(3+)and Cu(2+) were found to have profound inhibitory effects on the enzyme activity. Other metal ions like Ni(2+), Ca(2+), Mg(2+) and Mn(2+) had both enhancing and inhibitory effects. The enzyme showed optimal activity at a temperature of 40°C and pH 7.0. It was stable over a broad range of pH 6.0-10.0 and had a half life of 7h 30 min at 50°C.

Development of a non-denaturing electrophoresis system for characterization of neutralizing epitopes on HPV virus-like particles

The precise structure of the HPV16 major neutralizing epitope recognized by H16.V5 monoclonal antibody is unknown. This paper describes a novel polyacrylamide gel electrophoresis (PAGE) for separation of HPV virus-like particles (VLPs) using cetyltrimethylammonium chloride (CTAC) as a solubilizing agent. CTAC PAGE employs KOH/CH3CO2H (pH 4-5.4) as a buffer system, K+ as the leading ion and 3-aminopropionic acid as a trailing ion. The unique characteristics of a cationic electrophoresis system allow separation of VLPs without heat denaturation. HPV VLP gel migration patterns were dependent on pre-treatment conditions: (1) thiol-agent reduction alone resulted in a 174 kDa band (interpreted as a L1 trimer), a 53 kDa band (size of the L1 monomer), as well as higher Mr aggregates consistent with a pentamer size; (2) both heat denaturation and thiol-agent reduction resulted in a 53 kDa band. Western blot analysis showed that the 174 kDa L1 trimer was strongly immunoreactive with H16.V5 and HPV16 VLP ELISA positive human sera, whereas no reactivity was seen with the monomeric L1 unit. These data suggest that a structure consistent with the migration pattern of a L1 trimer contains the major neutralizing epitope recognized by the H16.V5 MAb and human sera.

cDNA cloning of mutant catalase in acatalasemic beagle dog: single nucleotide substitution leading to thermal-instability and enhanced proteolysis of mutant enzyme

The mutant catalase purified previously from acatalasemic dog liver was heat-labile but possessed normal activity, suggesting a mutation within the coding region distal from the catalytic site. The nucleotide and deduced amino acid sequences of acatalasemic beagle dog catalase were determined by analysis of cDNA obtained by 5'- and 3'-RACE and reverse transcriptase-polymerase chain reaction (RT-PCR) methods. Comparative analysis of cDNA sequences of normal and acatalasemic dog catalases indicated a single nucleotide difference where alanine(327) (G macro CT) was substituted with threonine (ACT). The mutant catalase, which was overexpressed in COS-1 cells, was heat-labile as previously observed with the purified enzyme from acatalasemic dog liver, indicating that this amino acid substitution can lead to structural instability. No catalase protein and activity were detected by immunoblotting and spectrophotomeric assay in acatalasemic dog reticulocytes although almost the same level of mRNA expression as that in the normal reticulocytes was observed. Pulse-labeling and immunoprecipitation examination indicated that the level of catalase synthesis in the acatalasemic dog reticulocytes was almost the same (approximately 80%) as that in the normal reticulocytes. On the other hand, the synthesized mutant catalase in reticulocytes was rapidly degraded (t(1/2): 1.8 h) compared with the normal catalase (t(1/2): 14.0 h) and this degradation was almost completely inhibited by lactacystin (LC). These results suggested that the proteolytic degradation mediated most likely by proteasome might be involved in disposing of the mutant catalase in acatalasemic erythroid cells.