Characterization of glutathione S-transferase enzyme from brown meagre (Sciaena umbra) and inhibitory effects of heavy metals.

Glutathione S-transferase (GST) detoxifies a broad spectrum of xenobiotics, especially in chemotherapeutic drugs, endogenous molecules, and environmental pollutants. Since the enzyme metabolizes toxic compounds, it has been extensively studied in many living things including aquatic organisms. In the current study, the GST enzyme was purified from brown meagre (Sciaena umbra) muscle tissue for the first time. Then, kinetic parameters of the enzyme were determined as optimum ionic strength: 20 mM Tris/HCl, optimum pH: 7.0 (Tris/HCl), and optimum substrate concentration: 3.125 mM. Eventually, inhibitory effects of the heavy metals were evaluated. IC50 values of the tested metal ions were calculated to be 0.1112, 0.6113, 0.727, and 0.7774 mM for Cd2+ , Fe3+ , Ag+ , and Cu2+ , respectively. Our results show that these heavy metals inhibit GST at very low concentrations which could cause dangerous results for aquatic systems.