Araştırmacılar(5)

• Cil, M.Y.
• Çoban, T. Abdül Kadir
• Kufrevioglu, O.I.
• Nalbantoglu, B.
• Ozdemir, H.

• CorrectionYalnız künye2010/r/ebyu/17728
  Corrigendum to "Sildenafil is a strong activator of mammalian carbonic anhydrase isoforms I-XIV" [Bioorg. Med. Chem. 17 (2009) 5791] (DOI:10.1016/j.bmc.2009.07.019)

  Coban, T. Abdülkadir; Beydemir, Şükrü; Gülcin, Ilhami; Ekinci, Deniz; Innocenti, Alessio; Vullo, Daniela; Supuran, Claudiu T.

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• ArticleYalnız künye2009/r/ebyu/17807
  Sildenafil is a strong activator of mammalian carbonic anhydrase isoforms I-XIV

  Abdülkadir Coban, T.; Beydemir, Şükrü; Gücin, Ilhami; Ekinci, Deniz; Innocenti, Alessio; Vullo, Daniela; Supuran, Claudiu T.

  Sildenafil citrate, a phosphodiesterase-5 (PDE5) inhibitor widely used for the treatment of erectile dysfunction was investigated for its interaction with the zinc-enzyme carbonic anhydrase (CA, EC 4.2.1.1), as it has in its molecule a piperazine moiety also found in some CA activators (CAAs). Sildenafil was a potent, low micromolar activator of several CA isozymes, such as CA I, VA and VI (KAs in the range of 1.08-6.54 μM), and activated slightly less the isoforms CA III, IV and VA (KAs of 13.4-16.8 μM). CA isozymes II, IX, XIII and XIV showed activation constants in the range of 27.5-34.0 μM, whereas the least activated isoforms were CA VII and XII (KAs of 72.9-73.0 μM). Sildenafil citrate was also given orally to Sprague-Dawley rats at 1 mg/kg body weight. Red blood cell CA activity was inhibited in the treated animals at 3-5 h post-administration (in the range of 60-85%), probably due to NO/nitrite formed by PDE5 inhibition or by another, unknown mechanism. Whether CA activation by sildenafil has clinical consequences in humans is beyond the scope of the present work and warrants further studies.

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• ArticleYalnız künye2008/r/ebyu/17725
  The inhibitory effect of dantrolene sodium and propofol on 6-phosphogluconate dehydrogenase from rat erythrocyte

  Gülçin, Ilharni; Beydemir, Şükrü; Abdulkadir Çoban, T.; Ekhici, Deniz

  Dantrolene sodium is an inhibitor of a skeletal muscle subtype of ryanodine receptors that stabilizes intracellular calcium concentrations and exerts neuroprotective effects in neurons submitted to excitotoxic challenges. Propofol is a short-acting intravenous anaesthetic. It has widely been used clinically as an intravenous general anaesthetic and as a sedative for critically ill patients. 6-Phosphogluconate dehydrogenase (6PGD) constitutes the pentose phosphate pathway and produces NADPH. It is also considered as a lipogenic gene since NADPH is a pivotal cofactor for lipogenesis. In this study, in vivo inhibition effects of dantrolene sodium and propofol on 6PGD were studied. The 6PGD activity was inhibited in vivo by both dantrolene sodium and propofol. Dantrolene at pharmacological dosage (10 mg/ kg) inhibited the significantly (p≤0.05) 3 h after dosing. However, the enzyme activity has been raised to the normal level at 5 h. On the other hand, at the pharmacological dosage (5 mg/kg), propofol also inhibited the significantly 1 h (p<0.05) and 3 h (p<0.05) after dosing. However, the enzyme activity has been raised to the normal level at 5 h.

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• ArticleYayıncıda açık erişim2008/r/ebyu/17632
  The effect of ethanol on erythrocyte carbonic anhydrase isoenzymes activity: An in vitro and in vivo study

  Çoban, T. Abdulkadir; Beydemir, Sükrü; Gülc̈in, Ilhami; Ekinci, Deniz

  The ethanol is a widely consumed as sedative-hypnotic drug throughout the world. In this study, the effects of ethanol were investigated on carbonic anhydrase (CA) enzyme activities both in vitro in human erythrocyte and in vivo in Sprague-Dawley rat erythrocyte. For in vitro study, the human carbonic anhydrase-I (HCA-I) and -II (HCA-II) are purified by Sepharose 4B-L-tyrosine-sulphanilamide affinity chromatography. In vivo CA enzyme activity was determined colorimetrically by using CO2-hydration method of Wilbur and Anderson. Rat blood samples were taken from each rat before and after the ethanol administration at different times (1 h, 3 h, and 5 h). Rat erythrocyte CA activity was significantly inhibited by pharmacological dosage of the ethanol (2mL.kg-1) for up to 3 h (p< 0.001) following intraperitoneally administration. The ethanol showed in vitro inhibitory effects on HCA-I and HCA-II hydratase activity, determined by colorimetrically using the CO2-hydratase method. The inhibitor concentrations causing up to 50% inhibition (IC50) were 2.09 M for HCA-I (r2:0.9273) and 1.83 M for HCA-II (r2:9749). In conclusion, it was demonstrated that carbonic anhydrase enzyme in erythrocytes was significantly inhibited by the ethanol both in in vitro and in vivo.

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• ArticleYalnız künye2007/r/ebyu/17778
  Effects of some metal ions on human erythrocyte glutathione reductase: An in vitro study

  Coban, T. Abdulkadir; Senturk, Murat; Ciftci, Mehmet; Kufrevioglu, O. Irfan

  In this study, we investigated inhibitory effects of some metal ions on human erythrocyte glutathione reductase. For this purpose, initially human erythrocyte glutathione reductase was purified 1051-fold in a yield of 41% by using 2′, 5′-ADP Sepharose 4B affinity gel and Sephadex G-200 gel filtration chromatography. SDS polyacrylamide gel electrophoresis was done in order to control the purification of enzyme. SDS polyacrylamide gel electrophoresis showed a single band for enzyme. A constant temperature (4°C) was maintained during the purification process. Enzyme activity was determined with the Beutler method by using a spectrophotometer at 340 nm. Hg2+, Cd2+, Pb2+, Cu2+, Fe 3+ and Al3+ exhibited inhibitory effects on the enzyme in vitro. Ki constants and IC50 values for metal ions were determined by Lineweaver-Burk graphs and plotting activity % vs. [I]. IC 50 values of Pb2+, Hg2+, Cu2+, Cd2+ , Fe3+ and Al3+ were 0.011, 0.020, 0.0252, 0.0373, 0.209 and 0.229 mM, and the Ki constants 0.0254±0.0027, 0.0378±0.0043, 0.0409±0.0048, 0.0558±0.0083, 0.403±0.043 and 1.137±0.2 mM, respectively. While Pb2+, Hg2+, Cd2+ and Fe3+ showed competitive inhibition, others displayed noncompetitive inhibition.

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• ArticleYayıncıda açık erişim2007/r/ebyu/17687
  Morphine inhibits erythrocyte carbonic anhydrase in vitro and in vivo

  Çoban, Taha Abdulkadir; Beydemir, Şükrü; Gülçin, Ilhami; Ekinci, Deniz

  Morphine is implicated in diverse functions, from development to immune modulation in the central and peripheral nervous systems. At the present time, morphine is one of the most effective antinociceptive agents used to manage pain. It has been used extensively in the clinical management of pain due to its potent analgesic effect. In this study, the in vitro and in vivo inhibitory effects of morphine on erythrocyte carbonic anhydrase (CA) were investigated. Human erythrocyte isoenzymes, HCA-I and HCA-II, were purified by Sepharose-4B affinity chromatography column with a yield of 66.95 and 62.82%, a specific activity of 3892.3 and 11663.2 EU/mg proteins with 745.1 and 2232.6-fold purification of each isoenzyme, respectively. To determine enzyme purity, sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) was performed. In vitro inhibition of erythrocyte HCA-I and HCA-II by morphine using the CO2-hydratase enzyme gave IC50 values 4.50×10 -5M (r2: 0.954) and 9.23×10-5M (r 2: 0.996), respectively. CA activity was significantly attenuated in vivo in Spraque-Dawley rats for up to 3 h (p<0.001) following intraperitoneal administration of morphine. In conclusion, morphine inhibited CA activity both in vitro and in vivo.

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• ArticleYalnız künye2002/r/ebyu/17719
  Purification and investigation of some kinetic properties of glucose-6-phosphate dehydrogenase from parsley (Petroselinum hortense) leaves

  Çoban, T. Abdül Kadir; Çifti, Mehmet; Küfrevioglu, O. Irfan

  In this study, glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate: NADP+ oxidoreductase, EC 1.1.1.49; G6PD) was purified from parsley (Petroselinum hortense) leaves, and analysis of the kinetic behavior and some properties of the enzyme were investigated. The purification consisted of three steps: preparation of homogenate, ammonium sulfate fractionation, and DEAE-Sephadex A50 ion exchange chromatography. The enzyme was obtained with a yield of 8.79% and had a specific activity of 2.146 U (mg protein)-1. The overall purification was about 58-fold. Temperature of +4°C was maintained during the purification process. Enzyme activity was spectrophotometrically measured according to the Beutler method, at 340 nm. In order to control the purification of enzyme, SDS-polyacrylamide gel electrophoresis was carried out in 4% and 10% acrylamide for stacking and running gel, respectively. SDS-polyacrylamide gel electrophoresis showed a single band for enzyme. The molecular weight was found to be 77.6 kDa by Sephadex G-150 gel filtration chromatography. A protein band corresponding to a molecular weight of 79.3 kDa was obtained on SDS-polyacrylamide gel electrophoresis. For the enzymes, the stable pH, optimum pH, and optimum temperature were found to be 6.0, 8.0, and 60°C, respectively. Moreover, KM and Vmax values for NADP+ and G6-P at optimum pH and 25°C were determined by means of Line-weaver-Burk graphs. Additionally, effects of streptomycin sulfate and tetracycline antibiotics were investigated for the enzyme activity of glucose-6-phosphate dehydrogenase in vitro.

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• ArticleYalnız künye1998/r/ebyu/17833
  Investigation of the inhibition effects of some antibiotics on human erythrocyte carbonic anhydrase isozymes

  Coban, T.A.; Nalbantoglu, B.; Cil, M.Y.; Ozdemir, H.; Kufrevioglu, O.I.

  In this study, the in vitro effects of some antibiotics on carbonic anhydrase (CA) isozymes have been investigated. Human erythrocyte CA-I and CA-II isozymes were separately purified by affinity chromatography. Inhibition effects of four different antibiotics on CA isozymes were determined by using the CO2-Hydratase method. I50 values of antibiotics were obtained by drawing % Activity [Actibiotic] graphs. The obtained I50 values of cefazolin sodium, cephradine, sulbactan/cefoperazone and chloramphenicol sodium succinate were 9, 16, 19 and 48 mM on CA-I and 6, 10, 15 and 17 mM on CA-II, respectively. Antibiotics dosages should be taken into consideration because of the inhibition effect on CA which pH regulatory enzyme in body.

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