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  • Öğe
    Utilisation of Cu2O/CuO@N, O doped catalysts on activated carbon particles derived from biological wastes for highly active hydrogen production with sodium borohydride methanolysis
    (Elsevier BV, 2025-05) Cafer Saka
    Despite the significant advantages of hydrogen (H2) production via sodium borohydride (SB, NaBH4) methanolysis, it is important to further develop this reaction with more efficient and cost-effective catalysts. Here, in the first stage, pomegranate peels, which are widely consumed in the world and Turkey, were evaluated in the production of activated carbon as biowaste (PPAC). In the second stage, the obtained PPAC was hydrothermally treated with nitric acid for O atom doping on the surface (O-doped PAC). In the third stage, Cu2O/CuO and N atoms particles were doped on the O-doped PPAC by hydrothermal method (Cu2O/CuO@N, O-doped PPAC). These Cu2O/CuO@N, O doped PPAC nanoparticles were used for the first time for effective H2 production from NaBH4 methanolysis(SB/ H2P). The active regions obtained based on Cu2O, CuO, N, and O particles on the carbon support exhibited HGR values of 4775 and 40622 mL/min/gcat for PPAC and Cu2O/CuO@N, O-doped PPAC, respectively. A significant increase of approximately eight times was achieved in the hydrogen generation rate (HGR) value. The XPS, EDS, and FTIR analyses successfully confirmed both CuO particles and O, N atoms doping into the PPAC structure. The activation energy for this reaction was 29.45 kJ/mol.
  • Öğe
    Green-synthesized ZrFeO nanoparticles as efficient cathode materials in PEM fuel cells
    (Elsevier BV, 2025-01) Suna Tarhan; Arzu Ekinci; Orhan Baytar; Abdurrahman Akdag; Ömer Şahin
    This study explores the application of ZrFeO nanoparticles, synthesized from fig leaf extract through a green synthesis method, as cathode materials for PEM fuel cells. The nanoparticles, doped with FeO and varying Zr ratios, were combined with Pt metal and characterized using XRD, SEM, EDX, and TEM to analyze their structural and morphological properties. The particle sizes for FeO and Zr-doped FeO were determined to be 2 nm and 2.5 nm, respectively. The electrochemical active surface areas of the catalysts—Pt-FeO/C and Zr-doped variants (PtFeO/C-1 wt%Zr, PtFeO/C-5 wt%Zr, and PtFeO/C-10 wt%Zr)—were measured as 97, 154, 138, and 119 m2/gPt, respectively, demonstrating a significant enhancement in surface area with the incorporation of Zr at optimal doping levels. Catalyst retention after 250 cycles was 29% for Pt–FeO/C, 60% for 1 wt% Zr-doped Pt–ZrFeO/C, 93% for 5 wt% Zr-doped Pt–ZrFeO, and 71% for 10 wt% Zr-doped Pt–ZrFeO. Performance testing at 70 °C revealed a hierarchy of catalytic activity: Pt–ZrFeO/C > Pt–FeO/C > Pt/C. The findings highlight the potential of green-synthesized ZrFeO nanoparticles as effective support materials for cathode catalysts, offering improved performance in PEM fuel cells while markedly reducing platinum dependency. This innovative approach integrates environmental sustainability with technological progress in fuel cell applications.
  • Öğe
    Predictors of Breastfeeding Success in Postpartum Period: Delivery Type, Postpartum Support, and Postpartum Depression
    (Ataturk Universitesi, 2024-12-23) Ayşegül Kılıçlı; Sidar Gül
    This study aimed to investigate the association between delivery type, postpartum support need and postpartum depression on breastfeeding success in the first postpartum month. Methods: This study, conducted between August 8, 2022 and August 31, 2023, was comparative, prospective and cross‐sectional. Sample consisted of 300 women (150 vaginal, 150 cesarean section). Data were collected using Descriptive Information Form, Postpartum Support Questionnaire, Edinburgh Postpartum Depression Scale, and Bristol Breastfeeding Assessment Tool. Multiple linear regression was used to identify the predictors of breastfeeding success. Results: Those who did not received sufficient support rate was 50.7%, the presence of postpartum depression was 54.0%, and the mean breastfeeding success score was 6.4±0.9 which was moderate. Cesarean delivery (β=‐0.149, p<.01), increased need for postpartum support (β=‐0.203, p<.01) and postpartum depression (β=0.261, p<.01) were significant predictors which were explaining 21.0% of total variance in breastfeeding success. The breastfeeding success of cesarean section mothers who did not have postpartum depression but received inadequate support decreased by 20.3% compared to vaginal birth mothers. Mothers who gave birth by caesarean section, did not receive postpartum support and were at risk of postpartum depression had the lowest breastfeeding success. Conclusion: Cesarean section, postpartum support, and postpartum depression are factors that significantly affect breastfeeding success. Therefore, breastfeeding counselling services for mothers in the postpartum care process should be planned and implemented individually to address mode of delivery, need for postpartum support and postpartum depression.
  • Öğe
    The validity and reliability study of the Turkish version of the Ethical Awareness Scale
    (Informa UK Limited, 2024-12-28) Gülcan Eyüboğlu; Nevin Doğan; Arnel Böke Kiliçli; Zehra Göçmen Baykara; Aimee Milliken
    The heightened focus on patient safety and the quality of nursing care in intensive care units underscores the necessity for reliable tools to evaluate nurses’ ethical awareness. This study was aimed to evaluate the psychometric properties of the Turkish version of the Ethical Awareness Scale in a sample of intensive care nurses. Data were collected from 249 intensive care nurses in Türkiye using the Turkish version of the 18-item Ethical Awareness Scale. The data were then analyzed using Rasch analysis. The Turkish version of the Ethical Awareness Scale demonstrated unidimensionality and an acceptable fit for the Rasch model. The person reliability and item reliability were 0.63 and 0.92, respectively. The Turkish version of the Ethical Awareness Scale was found to be a psychometrically valid and reliable instrument for measuring the ethical awareness levels of intensive care nurses.
  • Öğe
    Utilisation of green nitrogen-doped biomass-based hierarchical porous activated carbon particles for enhancement of electrochemical energy storage performance
    (Elsevier BV, 2025-02) İlyas Genel; Yavuz Yardım; Cafer Saka
    Activated carbon particles were obtained from rosehip wood-based carbon precursor by chemical activation with potassium hydroxide (RHAC). After this pyrolysis process, nitrogen-doped hierarchical porous carbon was prepared by ammonia activation (N-doped RHAC). The prepared carbonaceous materials were designed as an electrode for a supercapacitor. Standard electrochemical analyses were performed. The specific capacitance (Cs) of RHAC/GCE was determined to be 25 F/g at 2.5 mV/s and 23 F/g at 0.2 A/g. In contrast, the N-doped RHAC/GCE demonstrated significantly higher Cs values of 119 F/g at 2.5 mV/s and 121 F/g at 0.2 A/g. According to CV and GCD measurements, the N-doped RHAC material exhibited approximately a fivefold increase in specific capacitance compared to the RHAC-based electrode. A specific capacitance retention rate of 94.6 % was obtained after 1000 cycles at a current density of 1.6 A/g. The surface properties and characteristics of the obtained materials were carried out by SEM, nitrogen adsorption, Raman, FTIR, EDS and XPS analyses. EDS and XPS analyses showed that N atom doping was successful. This study suggests that rosehip tree biomass-based N atom doped carbon material is suitable for supercapacitors as an electrode.
  • Öğe
    HEMOGLOBİN VE NİTRİT BAĞIMLI TİROZİN NİTRASYONU
    (2017) Karageçili, Hasan; Kılınç, Kamer
    Nitric oxide (NO) reacts with oxyhemoglobin or oxymyoglobin resulting in the generation of nitrate and metHb or metMb. Unlike the case of nitrate, nitrite is not an innocuous end product of NO oxidation. Hemoproteins including several peroxidases are shown to cause nitrite oxidation in the presence of H2O2. Reactive nitrogen oxides generated in hemoprotein-catalyzed nitrite oxidation are held responsible for bactericidal and cytotoxic actions of nitrite. In this study with Griess method the oxidation of nitrite to nitrate in the presence of H2O2 by hemoglobin were searched. No nitrite oxidation was observed either in the absence of H2O2 or hemoglobin, showing that the reactive species causing nitrite oxidation is a oxoferryl complex (compound I) formed from the reaction of H2O2 with hemoglobin. In this study, similar to peroxidase enzymes, we found that hemoglobin causes the nitration of tyrosine. Hemoglobin-catalyzed tyrosine nitration was pH-dependent with the optimum pH of 6,0. Hemoglobin and H2O2 were essential components for tyrosine nitration. We have not observed any tyrosine nitration without hemoglobin even at the lowest pH studied. However during hemoglobin-catalyzed nitrite oxidation in the presence of H2O2, nitrating species are produced. We conclude that, by the series of reactions between hemoglobin, H2O2 and nitrite, nitrogen dioxide radical (NO2 - ) and/or peroxynitrite like reactive species are produced, and these species are responsible for tyrosine nitration.
  • Öğe
    Carbonic Anyhdrase Enzyme From The Siirt Mohair Goat Liver :Purification, Characterization and Assessment of Enzyme Kinetics Against Metal Toxicity
    (2017) Yerlikaya, Emrah; Karagecili, Hasan; Demirdag, Ramazan; Kaya, Mustafa Oguzhan
    Because of their physiological and clinical roles, carbonic anhydrases (CAs) are the most studied enzymes. In earlier studies; CA enzymes have been purified and characterized from the tissues and erythrocytes of many organisms such as; dog, swine, sheep, chicken, bee, fish, bovine, bacteria and human. In this study, the CA enzyme has purified from Siirt Mohair Goat liver tissue with 1930.84 EU x mg-1 of specific activity, 57.28% of purification yield and 80.55 of purification folds. The purity of the purified enzyme has confirmed by SDS-PAGE. As the characterization of CA enzyme’s in Siirt Mohair Goat liver has been done; the optimum ionic strength=25 mM, the optimum pH= 8.0, the optimum temperature= 40ºC and the stable pH= 7.0 has been determined. Inhibitory effects of some metal ions have been examined on the purified CA enzyme. IC50 values of inhibiting metal ions were found as 2.24, 2.76, 2.36, 3.20, 2.55, 2.25, 3.28, 2.13, 3.10, 1.75, 2.16 and 3.50 mM for Al3+, Ni2+, Cd2+, Cu2+, Pb2+, Ba2+, Zn2+, B3+, Fe3+, Se2+, Ag+ and Co2+ respectively. As a result, CA enzyme was first purified from the
  • Öğe
    Effects of some heavy metals on the activities of carbonic anhydrase enzymes from tumorous and non-tumorous human stomach
    (2015) Yerlikaya, Emrah; Demirdag, Ramazan; Kufrevioglu, Omer Irfan; Gundogdu, Cemal
    In this study, in vitro effects of certain heavy metals on the human carbonic anhydrase enzyme were examined. Inhibitory effects of metal ions (Pb2+, Cu2+, Fe2+, Cr2+, Al3+, Ni2+, Mn2+, Cd2+, Zn2+, and Mg2+) were observed in tumorous and non-tumorous tissue. IC50 values were calculated for metals. The Cu2+, Zn2+, Ni2+, Cd2+ and Mg2+ IC50 values of tumorous tissue were calculated as 0.034 mM, 0.426 mM, 0.597 mM, 0.878 mM and 2.52 mM, respectively. The Cu2+, Zn2+, Ni2+, Cd2+ and Mg2+ IC50 values of non-tumorous tissue were calculated as 0.067 mM, 0.991 mM, 1.065 mM, 1.724 mM and 6.13 mM, respectively. Carbonic anhydrase activity was measured as described by Wilbur and Anderson. Hydratase activity was used to determine IC50 values. In this study, tumorous and non-tumorous human stomach tissues were selected due to the fact that among the diseases, stomach cancer has one of the highest mortality rates. Stomach cancer, a type of cancer affecting the digestive system, is a fatal disease in living systems. The effects of metals on the CA enzyme were investigated due to the extremely important role that CA enzymes play in living beings.
  • Öğe
    Inhibition Effects of Some Sulfonamides on Carbonic Anhydrase from European seabass (Dicentrachus labrax)
    (2011) Erdem, Deryanur; Yerlikaya, Emrah; Ceyhun, Saltuk Bugrahan; Demirdag, Ramazan; Senturk, Murat; Erdogan, Orhan; Kufrevioglu, Omer Irfan
    Alpha-carbonic anhydrase (EC: 4.2.1.1; CA) was purified from European seabass gill and liver. The purification procedure was composed of preparation of homogenate (or hemolysate) and affinity chromatography on Sepharose 4B-tyrosine-sulfanilamide. Some sulfonamides exhibited in vitro inhibitory effects on the enzyme activity. Ki constants and IC50 values for these drugs were determined by Lineweaver-Burk graphs and plotting activity % vs. [I], respectively. IC50 values of sulfanilamide, mafenide, acetazolamide, 2-amino-1,3,5-tiyadiazol-5 sulfonamide were 980 ??M, 142 ??M, 20 ??M and 34 ??M for gill carbonic anhydrase (GCA), 126 ??M, 23 ??M, 14 ??M and 2.58 ??M for liver carbonic anhydrase (LCA), respectively. Some sulfonamides exhibited much stronger inhibitory activity against GCA and LCA at low micromolar concentrations with the Ki values ranging from 0.21 to 76.0 ??M as compared with other CAs.
  • Öğe
    Purification and Characterization of a-Carbonic Anhydrase II from Sheep Liver and Examining the Inhibition Effect of Kanamycin on Enzyme Activity
    (2012) Comakli, Veysel; Yerlikaya, Emrah; Demirdag, Ramazan; Kufrevioglu, Omer Irfan
    Sheep carbonic anhydrase - II (SCA-II) (E.C: 4.2.1.1) was purified from sheep liver and some characteristic properties were investigated. The enzyme was purified approximate 43.1-fold with a yield of 38.6%, and a specific activity of 4000 EU/mg proteins. For the enzyme, optimum pH, optimum temperature, optimum ionic strength and stable pH were determined to be 7.5, 40 ºC, 10 mM and 8.5, respectively. The molecular weight was found 29 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Kanamycin exhibited in vitro inhibitory effect on the enzyme activity.
  • Öğe
    Purification of CA Isoenzymes from Human Cancerous Colon Tissue and Inhibitory Effects of Some Analgesics on Enzyme Activity
    (2012) Demirdag, Ramazan; Yerlikaya, Emrah; Kufrevioglu, Omer Irfan; Gundogdu, Cemal
    Carbonic Anhydrase (CA) is an enzyme which is responsible for the hydration of carbon dioxide to carbonic acid and it also takes places in many biological processes in the living organisms. In this study, CA isoenzymes (CA II and CA IX) together were purified 78.4 fold with a yield of 54.86 and specific activity of 106.67 by using Sepharose 4B-L-tyrosine sulfanilamide affinity chromatography. In SDS-PAGE molecular weights of CA II and CA IX were calculated as 29 kDa and 56 kDa respectively. Besides inhibitory effects of some analgesics on purified total enzyme was investigated. IC50 values were found as 0.0077, 0.025, 0.011 and 0.04 mM for dexketoprofen, pethidine, phenyramidol and tramadol respectively.
  • Öğe
    Siirt Tiftik Keçisi Böbrek Dokusundan Karbonik Anhidraz Enziminin Saflaştırılması, Karakterizasyonu ve Bazı Biyokimyasal Özelliklerinin Araştırılması
    (2016) Yerlikaya, Emrah; Karagecili, Hasan; Demirdag, Ramazan; Kaya, Mustafa Oguzhan
    Carbonic anhydrase (CA) (E.C:4.2.1.1) is a group of metalloenzyme containing zinc widely distributed from the simplest organisms such as bacteria to the most complex organisms such as plants and animals. CA inhibitors are some of the principal drugs used in the management of canine and feline glaucoma. In earlier studies; CA enzymes successfully have been purified and characterized from many living things such as; sheep, chicken, fish, bovine and human. In this study, the CA enzyme has purified from Siirt Mohair Goat kidney tissue with 902.9 EU x mg-1 of specific activity, 50.19% of purification yield and 83.54 of purification folds by using Sepharose-4B-L-tyrosine-sulfonamide affinity column. The purity of the purified enzyme has confirmed by SDS-PAGE. As the characterization of CA enzyme’s in Siirt Mohair Goat kidney has been done; the optimum ionic strength=25mM, the optimum pH=8.5, the optimum temperature=45ºC and the stable pH=7.0 has been determined. Inhibitory effects of Al3+, Ni2+, Cd2+, Pb2+, Ba2+, Zn2+, B3+, Fe3+, Se2+, Ag+ and Co2+ metal ions have been examined on the purified CA enzyme. Inhibition graphics have been drawn in order to find the IC50 values of metals showing inhibition.
  • Öğe
    INHIBITORY EFFECTS OF SOME PESTICIDES AND METALS ON CARBONIC ANHYDRASE PURIFIED FROM SHABUT FISH BARBUS GRYPUS ) GILL TISSUE
    (2019) Yerlikaya, Emrah
    Carbonic anhydrase enzyme catalyzes the reversible inter-conversion of CO2 and HCO3. The enzyme is crucial for the osmotic balance and acid–base regulation in the fish. It is well-known that gills of fish play the most important role in acid–base relevant ion transfer, the transfer of H+ and/or HCO3, for the maintenance of systemic pH. Many researches have shown that fish are the species that is the most susceptible to environmental toxins. In addition, these toxins firstly encounter the gill tissue in fish. In this study, the carbonic anhydrase enzyme was purified 198.6-folds with 58.8% yield from Shabut Fish (Barbus grypus) gill tissue by Sepharose-4B-L-tyrosine-sulfanilamide affinity column. The specific activity was determined as 2.92 EU/mg protein. The molecular weight determined by sodium dodecyl sulfate–polyacrylamide gel electrophoresis was found to be about 29.9 kDa. Inhibitory effects of some pesticides (Spinosad and Dimethoate) and metal ions (Al3+, Cu2+, Ba2+, Fe2+, Mn2+, Se2+) were examined on the purified carbonic anhydrase enzyme. Inhibition graphics were drawn in order to find the IC50 values of metals and pesticides showing inhibition. The kinetic parameters of this enzyme were determined for its esterase activity, with 4-nitrophenyl acetate as substrate.
  • Öğe
    PURIFICATION, CHARACTERIZATION OF GLUTATHIONE S-TRANSFERASE FROM THE GILL TISSUE OF LAKE VAN FISH AND INHIBITION EFFECTS OF SOME METAL IONS AND PESTICIDES
    (2019) Zaric, Yakup; Yerlikaya, Emrah; Demirdag, Ramazan
    Glutathione-S-Transferases (GSTs) are xenobiotic metabolizing enzymes that protect cells from toxic drugs and environmental electrophiles. Furthermore, these enzymes have effected the regulators of oxidative stress and toxicity [1]. In earlier studies; GST enzymes have been purified and characterized from many living things such as sheep, bird, fish, bacterium, bovine and human. This study proves the purification and characterization of GST enzyme (E.C. 2.5.1.18) from the Gill Tissue of Lake Van Fish by affinity chromatography. Inhibitory effects of some metal ions and pesticides on GST activity were determined with using the CDNB method under in vitro conditions. Purification degree for the purified enzyme was controlled by SDS-PAGE. Optimal pH, optimal ionic strength, optimal temperature and stable pH were determined as 7.3, 120 mM, 35°C, 8.0, respectively. Inhibitory effects of Al3+, Ba2+, B3+ and Se2- metal ions and Oxamyl, Diniconazole, Carbofuran, Tebuconazole and Atrazine pesticides have been examined on the purified GST enzyme. Inhibition graphics have been drawn in order to find the IC50 values of metals and pesticides showing inhibition from Activity % -[Inhibitor] graphs. Consequently, in vitro inhibition rank order was determined as Al3+ > Ba2+ > Se2- > B3+ for metal ions, Carbofuran > Tebuconazole > Oxamyl > Atrazine > Diniconazole for pesticides.
  • Öğe
    Purification of carbonic anhydrase-II from sheep liver and inhibitory effects of some heavy metals on enzyme activity
    (2012) Demirdag, Ramazan; Yerlikaya, Emrah; Kufrevioglu, Omer Irfan
    In this study; sheep carbonic anhydrase-II (SCA-II) (E.C: 4.2.1.1) was purified from sheep liver and in vitro effects of heavy metals on the enzyme was examined. SCA-II isozyme was purified with about 203 purification fold, a specific activity of 2320 EU/mg-protein and a yield of 72 by using Sepharose-4B-L tyrosine-sulfanilamide affinity gel chromatography. Purity of the SCA-II enzyme was verified by SDS-PAGE technique and subunit molecular mass of the enzyme was found as 29 kDa. In addition to this, inhibitory effects of some metal ions on the enzyme were examined. In this study, sheep liver tissue was chosen; because the liver is an organ in which metal wastes of air, water and food are collected and it is easy to obtain the liver tissue. Because of the very important duties of CA enzyme on living beings, the effect of metals on the CA enzyme was investigated.
  • Öğe
    Examination of Changes in Enzyme Activities of Erythrocyte Glucose 6-Phosphate Dehydrogenase and 6-Phosphogluconate Dehydrogenase in Rats Given Naringenin and Lead Acetate
    (2015) Demirdag, Ramazan; Comakli, Veysel; Ozkaya, Ahmet; Sahin, Zafer; Dag, Uzeyir; Yerlikaya, Emrah; Kuzu, Muslum
    In our study, controlled experimental groups were performed by giving substances Lead acetate, Naringenin andNaringenin+Lead acetate to rats in vivo conditions Changes in the glucose 6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD) enzyme activities in erythrocytes of rats in these groups were compared to the Control group. An inhibition significant degree for G6PD enzyme activity was observed in all groups when compared to the Control group (p < 0.001). While inhibition significant degree for 6PGD enzyme activity was observed in Lead acetate groups (p < 0.001), no significant effect was observed in the Naringenin and Naringenin + Lead acetate groups (p > 0.05). In addition, lead levels in the groups of rats were determined using an inductively coupled plasma mass spectrometer (ICP-MS) device. As a result of measurements by the ICP-MS device, lead levels were found as an average of 42.9 ± 2.51, 36.71 ± 1.13, 172.16 ± 9.63, and 95.07 ± 5.87 ppm in the Control, Naringenin, Lead acetate and Naringenin+Lead acetate groups, respectively. Our results were shown thatNaringenin has protective effects on the Lead acetate induced oxidative stress erythrocytes in rat.
  • Öğe
    Expression of hCA IX isoenzyme by using sumo fusion partner and examining the effects of antitumor drugs
    (2015) Yerlikaya, Emrah; Erdogan, Orhan; Demirdag, Ramazan; Senturk, Murat; Kufrevioglu, Omer Irfan
    Objective: In this study, investigating the effects of inhibition of the enzyme activity of some antitumor drugs and the Cancer-Related Human Carbonic Anhydrase IX (hCA IX) isoenzyme expressing as a SUMO fusion protein in an Escherichia coli expression system were aimed. Methods: hCA IX isoenzyme was expressed using SUMO fusion technology. The fusion protein was expressed in a totally soluble form and the expression was verified by SDS-PAGE analysis. Affinity chromatography was used in the purification processes. The effects of certain antitumor drugs on enzyme activity were investigated in vitro conditions by using esterase activity. IC50 values of drugs showing the inhibitory effect were calculated. Inhibition types and Ki values for antitumor drugs, which inhibit the enzyme, were determined by separately plotting Lineweaver- Burk plots. Results: The molecular weight of the fusion protein was approximately 85kDa. The optimal induction concentration of IPTG and the growth temperature were found to be 1.0mM and 30oC. The fusion protein was purified at approximately 3.07-fold with a yield of 92.58%, and a specific activity of 43707EU/mg proteins by nickel nitrilo-triacetic acid resin chromatography.
  • Öğe
    Heavy metal ion inhibition studies of human, sheep and fish ?-carbonic anhydrases
    (2013) Demirdag, Ramazan; Yerlikaya, Emrah; Senturk, Murat; Kufrevioglu, Omer Irfan; Supuran, Cladiu T.
    Carbonic anhydrases (CAs, EC 4.2.1.1) were purified from sheep kidney (sCA IV), from the liver of the teleost fish Dicentrarchus labrax (dCA) and from human erythrocytes (hCA I and hCA II). The purification procedure consisted of a single step affinity chromatography on Sepharose 4B-tyrosine-sulfanilamide. The kinetic parameters of these enzymes were determined for their esterase activity with 4-nitrophenyl acetate as substrate. The following metal ions, Pb2+, Co2+, Hg2+, Cd2+, Zn2+, Se2+, Cu2+, Al3+ and Mn3+ showed inhibitory effects on these enzymes. The tested metal ions inhibited these CAs competitively in the low milimolar/submillimolar range. The susceptibility to various cations inhibitors differs significantly between these vertebrate ?-CAs and is probably due to their binding to His64 or the histidine cluster.
  • Öğe
    Influence of pesticides on the pH regulatory enzyme, carbonic anhydrase, from European Seabass liver and bovine erythrocytes
    (2012) Demirdag, Ramazan; Yerlikaya, Emrah; Aksakal, Ercüment; Kufrevioglu, Omer Irfan; Ekinci, Deniz
    The objective of this study was to assess the inhibitory effects of six commonly used pesticides, cyhalothrin, cypermethrin, dichlorvos, methamidophos, chlorpyrifos and methylparathion, on the pH regulatory enzyme carbonic anhydrase (CA) of Dicentrarchus labrax (European Seabass) liver (dCA) and bovine erythrocytes (bCA). Results of the study showed that the pesticides displayed quite variable inhibition profiles with KI values ranging from 0.376 to 26.164 M against dCA, and from 1.174 to 53.281 M against bCA. Methyl- parathion was the most effective inhibitor for both enzymes. Overall data show that all of the tested pesticides inhibit both dCA and bCA at low concentrations indicating that indiscriminate use of these pesticides might cause disruption of acid base regulation resulting in animal deaths. Our results also point out that susceptibility to these pesticides varies among CAs from different organisms.
  • Öğe
    Purification and characterization of carbonic anhydrase from the teleost fish Dicentrarchus labrax (European seabass) liver and toxicological effects of metals on enzyme activity
    (2011) Ceyhun, Saltuk Bugrahan; Senturk, Murat; Yerlikaya, Emrah; Erdogan, Orhan; Kufrevioglu, Omer Irfan; Ekinci, Deniz
    Carbonic anhydrase (EC 4.2.1.1; CA) was purified and characterized from the liver of the teleost fish Dicentrarchus labrax (European seabass) for the first time. The purification procedure consisted of a single step affinity chromatography on Sepharose 4B-tyrosinesulfanilamide. The enzyme was purified 78.8-fold with a yield of 46%, and a specific activity of 751.72U/mg proteins. It has an optimum pH at 7.5; an optimum temperature at 25 ?C; an optimum ionic strength at 10mM and a stable pH at 8.5. The kinetic parameters of this enzyme were determined for its esterase activity, with 4-nitrophenyl acetate (NPA) as substrate and the purified enzyme had an apparent KM and Vmax values of 0.44mM and 0.249 mol x min-1, respectively. The following metals, Al+3, Cu+2, Pb+2, Co+3, Ag+1, Zn+2 and Hg+2 showed inhibitory effects on the enzyme. Al+3 and Cu+2 exhibited the strongest inhibitory action. Pb+2 was moderate inhibitor, whereas other metals showed weaker actions. All tested metals inhibited the enzyme in a competitive manner. Our findings indicate that these metals inhibit the fish enzyme in a similar manner to other -CAs from mammals investigated earlier, but the susceptibility to various metals differ between the fish and mammalian enzymes. Our results also demonstrate that these metals might be dangerous at low micromolar concentrations for fish CA enzymes.