Some metals inhibit the glutathione S-transferase from Van Lake fish gills

Glutathione S-transferases (GSTs) are the superfamily of multifunctional detoxification isoenzymes and play important role cellular signaling. The present article focuses on the role of Cd²⁺ , Cu²⁺ , Zn²⁺ , and Ag⁺ in vitro inhibition of GST. For this purpose, GST was purified from Van Lake fish (Chalcalburnus tarichii Pallas) gills with 110.664 EU mg^-1 specific activity and 79.6% yield using GSH-agarose affinity chromatographic method. The metal ions were tested at various concentrations on in vitro GST activity. IC₅₀ values were found for Cd⁺² , Cu⁺² , Zn⁺² , Ag⁺ as 450.32, 320.25, 1510.13, and 16.43 μM, respectively. K_i constants were calculated as 197.05 ± 105.23, 333.10 ± 152.76, 1670.21 ± 665.43, and 0.433 ± 0.251 μM, respectively. Ag⁺ showed better inhibitory effect compared with the other metal ions. The inhibition mechanisms of Cd²⁺ and Cu²⁺ were non-competitive, whereas Zn²⁺ and Ag⁺ were competitive. Co²⁺ , Cr²⁺ , Pb²⁺ , and Fe³⁺ had no inhibitory activity on GST.