Carbonic anhydrase activity from the gilthead sea bream (Sparus aurata) liver: the toxicological effects of heavy metals

Purification and biochemical characterization of a novel carbonic anhydrase II from erythrocytes of camel (Camelusdromedarius)

A novel carbonic anhydrase II (CA II) from erythrocytes of camel (Camelus dromedarius) was purified to homogeneity using affinity chromatography and biochemically characterized. Specific activity of 140.88 U/mg was obtained with 745.17-fold purification and 25.37% yield. The enzyme was a monomer with a lower molecular weight (25 kDa) and lower Zn content (0.50 mol of Zn per mol of protein). The enzyme showed higher optimum temperature (70 °C) and pH (pH 9.0), moreover, it was stable at higher temperatures and strongly alkaline pH as judged by thermodynamic parameters (Ea, kd, Ed, t1/2, D-value, Z-value, ΔH, ΔG and ΔS). The enzyme was inhibited by cations (Al3+, Ca2+, Cd2+, Co2+, Cr3+, Cu2+, Fe3+, Ni2+, Mg2+ and Zn2+) as well as by anions (Br‾, CH3COO‾, ClO4‾, CN‾, F‾, HCO3‾, I‾, N3‾, NO3‾ and SCN‾), some anions (C6H5O73-, CO32-, SeO3‾ and SO42-) does not affect enzyme activity. Effect of various chemicals on enzyme activity was also investigated. Km, Vmax, kcat and kcat/Km values for 4-NPA were found to be 1.74 mM, 0.0093 U/mL, 0,0039 s-1 and 0,0023 s-1 mM-1, respectively. With these interesting biochemical properties, camel CA II represents promising candidate for harsh industrial applications, in particular, for a successful biomimetic CO2 sequestration process.

Chemical and biochemical responses to sub-lethal doses of mercury and cadmium in gilthead seabream (Sparus aurata)

Specimens of Sparus aurata were exposed to sub-lethal concentrations of Hg and Cd for 25 days and the levels of both metals were investigated in organs and tissues. Bioaccumulation of Hg decreased as follow: gills > kidney > liver > skin > muscle, while the order of Cd bioaccumulation was: liver > kidney > gills > skin > muscle. Immediately after exposure, both metals showed the highest bioaccumulation in gills and skin indicating that these organs are reliable targets for biomonitoring studies after short term exposure. Metals introduction caused a significant time-dependent concentrations increase in kidney and liver, while in the muscle a significant increase of Hg was recorded only at the end of the experimentation. The effects of exposure were also investigated, at biochemical level, in the liver, which represents the main target of xenobiotics biotransformation and metabolism in fish. Exposed fishes exhibited a reduction of total lipid level, a decrease of polyunsaturated fatty acids (PUFA), together with a MDA increase. This suggests a direct effect of contaminants on oxidative stress induction that, through the MDA increase, altered the membrane fatty acids composition decreasing the PUFA content. As it regards molecular markers related to oxidative stress and lipid metanolism, a significant increase of Nrf2, Hif-1α and Ampk and a decrease of Fas were observed after exposure to both metals, while an Nf-kB increase was recorded in specimens exposed to Hg, docuemnting a correlation with oxidative stress and consequent metabolism adaptation. Finally, these results suggest the possibility to adopt these biomarkers to explore fish metabolic responses to environmental pollution.

Metal accumulation induces oxidative stress and alters carbonic anhydrase activity in corals and symbionts from the largest reef complex in the South Atlantic ocean

We evaluated the influence of metal accumulation on the oxidative status [lipid peroxidation (LPO) and total antioxidant capacity (TAC)] and carbonic anhydrase (CA) activity in host and symbionts of the coral Mussismilia harttii and the hydrocoral Millepora alcicornis collected in Abrolhos Reef Banks (Northeast Brazil), potentially impacted by a major mine dam rupture. Considering metal levels measured in reefs worldwide, Abrolhos corals had higher Fe and Mn levels than expected for preserved offshore reefs. Increasing concentrations of arsenic (As), chromium (Cr) and manganese (Mn) drove inhibition of CA and increased oxidative damage in the hydrocoral M. alcicornis. The impairment of enzymatic activity in the symbiotic algae of M. alcicornis may be related to the oxidative stress condition. The hydrocoral M. alcicornis was more affected by metals than the coral M. harttii, which did not show the expected CA inhibition after metal exposure. Our results suggest that CA activity can be applied as a complementary biomarker to evaluate the physiological impacts of environmental metal contamination in reefs. Also, the metal levels and biochemical biomarkers reported in the present study may provide reference data to monitor the health of reefs impacted by a relevant dam rupture.

Carbonic anhydrase inhibitor induces otic hair cell apoptosis via an intrinsic pathway and ER stress in zebrafish larvae

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CA inhibitor EZA causes lateral line organ death in zebrafish larvae.

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Neuromast hair cells are especially sensitive to EZA during embryo development.

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EZA induces apoptosis in otic hair cells via an intrinsic pathway and ER stress.

Carbonic anhydrase (CA) catalyzes reversible hydration of CO₂ to HCO₃⁻ to mediate pH and ion homeostasis. Some chemical pollutants have been reported to have inhibitory effects on fish CA. In this study, we investigated effects of a CA inhibitor ethoxyzolamide (EZA) on neuromasts development during zebrafish embryogenesis, since embryogenesis in aquatic organisms can be particularly sensitive to water pollution. EZA caused alteration of pH and calcium concentration and production of reactive oxygen species (ROS) in larvae, and induced apoptosis in hair cells especially in the otic neuromast, in which CA2 was distributed on the body surface. mRNA levels of apoptotic genes and caspase activities were increased by EZA, whereas anti-oxidants and apoptotic inhibitors, Bax, NF-κB, and p53 inhibitors significantly relieved the induction of hair cell death. Also, mRNA levels of Bip and CHOP, which are induced in response to ER stress, were upregulated by EZA, suggesting that EZA induces otic hair cell apoptosis via the intrinsic mitochondrial pathway and ER stress. Our results demonstrated an essential role of CA in neuromast development via maintenance of ion transport and pH, and that the CA, which is directly exposed to the ambient water, shows marked sensitivity to EZA.

Inhibition effects of some pesticides and heavy metals on carbonic anhydrase enzyme activity purified from horse mackerel (Trachurus trachurus) gill tissues

The gill tissue is the main site of metabolic enzymes or compensation, with the kidney tissue playing a supporting role. At the gill tissue, carbonic anhydrase enzymes (CAs) catalyze the hydration of CO₂ to HCO₃^- and H⁺ for production to the H₂O. In this work, the CA enzyme was purified from horse mackerel (Trachurus trachurus) gill with a specific activity of 21,381.42 EU/mg, purification fold of 150.61, total activity of 2347.68 EU/mL, and a yield of 16.13% using sepharose 4B-L-tyrosine-sulfanilamide affinity gel chromatography. For recording the enzyme purity, gel electrophoresis was performed, and single band was seen. The molecular weight of this enzyme was found approximately 35 kDa. Also, the inhibitory effects of different pesticides such as thiram, clofentezine, propineb, deltamethrin, azoxystrobin, and thiophanate and heavy metal ions such as Fe²⁺, Cu²⁺, Co²⁺, Pb²⁺ Hg²⁺, and As³⁺ on horse mackerel gill tissue CA enzyme activities were investigated. Our results indicated that these pesticides and metal ions showed inhibitory effects at low nanomolar and millimolar concentrations for fish gill CA enzymes, respectively.

Purification and characterization of the carbonic anhydrase enzyme from horse mackerel (Trachurus trachurus) muscle and the impact of some metal ions and pesticides on enzyme activity

In this paper, the total carbonic anhydrase (CA) enzyme was purified from horse mackerel (Trachurus trachurus) muscle with a specific activity of 23,063.93 EU/mg, purification fold of 551.08, total activity of 1522.22 EU/mL and a yield of 18.50% using sulfanilamide affinity column chromatography. For obtaining the subunit molecular mass and enzyme purity, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for this part was performed and a single band was clearly recorded. The molecular mass of this enzyme was found approximately 35 kDa. The optimum temperature and pH values were obtained from Arrhenius plot. In addition, the inhibitory effects of different heavy metal ions (Fe²⁺, Cu²⁺, Co²⁺, Pb²⁺ Hg²⁺ and As³⁺) and some pesticides (thiram, clofentezine, propineb, deltamethrin, azoxystrobin and thiophanate) on horse mackerel (Trachurus trachurus) muscle tissue CA enzyme activities were investigated by utilizing esterase assay activity. The used metal ions and pesticides had IC₅₀ values in the range of 0.21-13.84 mM and 3.78-70.58 mM, respectively.

Carbonic anhydrase activity as a potential biomarker for acute exposure to copper in corals

Coral reefs are subjected to climate change and are severely impacted by human activities, with copper (Cu) being a relevant physiological stressor for corals at local scale. The ecological relevance of parameters measured at biochemical or cellular level is now considered an extremely important feature in environmental studies, and can be used as early warning signs of environmental degradation. In this context, the effects of acute exposure (96 h) to Cu were assessed on the maximum photochemical efficiency of zooxanthellae (Fv/Fm) and on the activity of key enzymes [carbonic anhydrase (CA) and Ca-ATPase] involved in coral physiology using the scleractinian coral Mussismilia harttii as a biological model. Corals were exposed to different concentrations of dissolved Cu (4.6-19.4 μg/L) using two different experimental approaches: a laboratory closed system and a marine mesocosm system. Fv/Fm values and Ca - ATPase activity were not affect by exposure to Cu in any of the exposure systems. However, a significant reduction in CA activity was observed in corals exposed to 11.9 and 19.4 μg Cu/L in the laboratory and at all concentrations of Cu tested in the mesocosm system (4.6, 6.0 and 8.5 μg/L). Based on the sensitivity of this enzyme to the short period of exposure to sublethal concentrations of Cu in both experimental approaches, the present study suggests the use of CA activity as a potential biomarker to be used in biomarker-based environmental monitoring programs in coral reefs.

Physiological traits of land snails Theba pisana as simple endpoints to assess the exposure to some pollutants

In the current study, the toxicity bioassay of three pollutants abamectin (ABM), thiamethoxam (TMX), and acrylamide (ACR) against land snails Theba pisana was measured. Also, the ecotoxicological effects of dietary exposure to sublethal concentration (1/20 LC₅₀) of these pollutants for 2-week exposure and 1-week recovery on some physiological endpoints evaluated as feeding activity, growth response, and carbonic anhydrase activity as a marker in charge of shell formation and seromucoid level as a marker in charge of mucus synthesis of the snails were studied. The results exhibited that the 48-h LC₅₀ values were 0.91, 313.8, and 45.7 μg/g dry food for ABM, TMX, and ACR, respectively. The sublethal concentrations of these pollutants in the diet after 2-week exposure were found to reduce the food consumption and inhibit growth rate of the snails. Also, the data illustrated that carbonic anhydrase activity was significantly decreased. On the other hand, there was a significant increase in the seromucoid level as a marker responsible for mucus synthesis in ABM- and TMX-exposed snails, while ACR showed significantly decreased level when compared to control. After 1-week recovery, the tested endpoints of treated snails were slightly repaired but still less than that of the untreated animals. The overall outcome of this investigation suggests the utility of this animal as a good bioindicator organism for ABM, TMX, and ACR exposure in pollution monitoring studies.

Inhibitory properties of some heavy metals on carbonic anhydrase I and II isozymes activities purified from Van Lake fish (Chalcalburnus Tarichi) gill

In this study, CA I and II isoenzymes were purified from Van Lake fish gills by using Sepharose-4B-L-tyrosine-sulfanilamide affinity chromatography and to determine the effects of some metals on the enzyme activities. For purified CA I isoenzyme, yield, specific activity, and purification fold were obtained as 42.07%, 4948.12 EU/mg protein, and 116.61 and for CA II isoenzyme, 7%, 1798.56 EU/mg protein, and 42.38 respectively. Activity of CA was determined by measuring "CO₂-hydratase activity". Purity control was checked by SDS-PAGE. In vitro inhibitory effect of Cu²⁺, Ag⁺, Cd²⁺, Ni²⁺ metal ions, and arsenic (V) oxide were also examined for both isozymes activities. Whereas Cu²⁺, Ag⁺, Cd²⁺, and Ni²⁺ ions showed inhibitory effects on both isozymes, arsenic (V) oxide showed activation effect. IC₅₀ values were calculated by drawing activity %-[I] graphs for metal ions exhibiting inhibitory effects. IC₅₀ values were determined as 3.39, 6.38, 13.52, and 206 μM for CA I isozyme and 6.16, 20.29, 46, and 223 μM for CA II isozyme respectively.

Functional Involvement of Carbonic Anhydrase in the Lysosomal Response to Cadmium Exposure in Mytilus galloprovincialis Digestive Gland

Carbonic anhydrase (CA) is a ubiquitous metalloenzyme, whose functions in animals span from respiration to pH homeostasis, electrolyte transport, calcification, and biosynthetic reactions. CA is sensitive to trace metals in a number of species. In mussels, a previous study demonstrated CA activity and protein expression to be enhanced in digestive gland by cadmium exposure. The aim of the present work was to investigate the functional meaning, if any, of this response. To this end the study addressed the possible involvement of CA in the lysosomal system response of digestive gland cells to metal exposure. The in vivo exposure to acetazolamide, specific CA inhibitor, significantly inhibited the acidification of the lysosomal compartment in the digestive gland cells charged with the acidotropic probe LysoSensor Green D-189, demonstrating in vivo the physiological contribution of CA to the acidification of the lysosomes. Under CdCl₂ exposure, CA activity significantly increased in parallel to the increase of the fluorescence of LysoSensor Green charged cells, which is in turn indicative of proliferation and/or increase in size of lysosomes. Acetazolamide exposure was able to completely inhibit the cadmium induced Lysosensor fluorescence increase in digestive gland cells. In conclusion, our results demonstrated the functional role of CA in the lysosomal acidification of Mytilus galloprovincialis digestive gland and its involvement in the lysosomal activation following cadmium exposure. CA induction could physiologically respond to a prolonged increased requirement of H⁺ for supporting lysosomal acidification during lysosomal activation.

Purification and characterization of the carbonic anhydrase enzyme from Black Sea trout (Salmo trutta Labrax Coruhensis) kidney and inhibition effects of some metal ions on enzyme activity

In this study, the carbonic anhydrase (CA) enzyme was purified from Black Sea trout (Salmo trutta Labrax Coruhensis) kidney with a specific activity of 603.77EU/mg and a yield of 35.5% using Sepharose-4B-l-tyrosine- sulphanilamide affinity column chromatography. For determining the enzyme purity and subunit molecular mass, sodiumdodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) was performed and single band was observed. The molecular mass of subunit was found approximately 29.71kDa. The optimum temperature, activation energy (Ea), activation enthalpy (ΔH) and Q10 values were obtained from Arrhenius plot. Km and Vmax values for p-nitrophenyl acetate of the purified enzyme were calculated from Lineweaver-Burk graphs. In addition, the inhibitory effects of different heavy metal ions (Fe(2+), Pb(2+), Co(2+), Ag(+) and Cu(2+)) on Black Sea trout kidney tissue CA enzyme activities were investigated by using esterase method under in vitro conditions. The heavy metal concentrations inhibiting 50% of enzyme activity (IC50) were obtained. Finally Ki values and inhibition types were calculated from Lineweaver-Burk graphs.

In vitro inhibitory effects of palonosetron hydrochloride, bevacizumab and cyclophosphamide on purified paraoxonase-I (hPON1) from human serum

In this study, we investigated the effects of the drugs, palonosetron hydrochloride, bevacizumab and cyclophosphamide, on human serum paraoxonase-I (hPON1) enzyme activity in in vitro conditions. The enzyme was purified ∼231-fold with 34.2% yield by using ammonium sulphate precipitation, DEAE-Sephadex A-50 ion-exchange chromatography and Sephadex G-200 gel-filtration chromatography from human serum. hPON1 exhibited a single protein band on the SDS polyacrylamide gel electrophoresis. The inhibition studies were performed on paraoxonase activity of palonosetron hydrochloride, bevacizumab and cyclophosphamide. Ki constants were found as 0.033±0.001, 0.054±0.003 mM and 3.419±0.518 mM, respectively. Compared to the inhibition rates of the drugs, palonosetron hydrochloride has the maximum inhibition rate. However, inhibition mechanisms of the drugs were determined as noncompetitive by Lineweaver-Burk curves.

The Complex Relationship between Metals and Carbonic Anhydrase: New Insights and Perspectives

Carbonic anhydrase is a ubiquitous metalloenzyme, which catalyzes the reversible hydration of CO₂ to HCO₃⁻ and H⁺. Metals play a key role in the bioactivity of this metalloenzyme, although their relationships with CA have not been completely clarified to date. The aim of this review is to explore the complexity and multi-aspect nature of these relationships, since metals can be cofactors of CA, but also inhibitors of CA activity and modulators of CA expression. Moreover, this work analyzes new insights and perspectives that allow translating new advances in basic science on the interaction between CA and metals to applications in several fields of research, ranging from biotechnology to environmental sciences.

The toxicological impacts of some heavy metals on carbonic anhydrase from gilthead sea bream (Sparus aurata) gills

It is known that heavy metals have toxic effects on fish. Insufficient measures are a serious problem in our country and around the world. This problem can threaten human health in areas where it is common for people to obtain nutrition from local bodies of water. In this study, the toxicological impacts of some heavy metals were investigated on carbonic anhydrase activity in gilthead gills. Carbonic anhydrase (CA) was purified from gilthead sea bream (Sparus aurata) gills with a specific activity of 2872.92 EU mg(-1) and a yield of 32.84% using affinity chromatography. The overall purification was approximately ∼ 84-fold. SDS-polyacrylamide gel electrophoresis showed a single band, and the MW was approximately 30.5 kDa (Soyut et al., 2008, 2012; Soyut and Beydemir, 2008, 2012; Kaya et al., 2013). The kinetic and characteristic properties of CA such as the optimum pH, stable pH, optimum temperature, activation energy (Ea), activation enthalpy (ΔH), Q10, Km and Vmax were determined. Cadmium (Cd(2+)), copper (Cu(2+)), nickel (Ni(2+)) and silver (Ag(+)) inhibited CA activity in in vitro conditions. Ki values were calculated for these metals. Ki values were 31.20mM for cadmium (Cd(2+)), 161.96 mM for copper (Cu(2+)), 10.79 mM for nickel (Ni(2+)) and 0.0082 mM for silver (Ag(+)) based on Lineweaver-Burk plots. Except for cadmium, heavy metals had the same inhibition mechanism. Cadmium was competitive, and the others were noncompetitive.