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    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.
  • [ X ]
    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.