Puri̇ficati̇on of thi̇oredoxi̇n reductase enzymc from rai̇nbovv trouth gi̇li ti̇ssucs and investi̇gati̇on the effects of some heavy metal i̇ons on the enzyme acti̇vi̇ty

In the present study, Thioredoxin system is formed of thioredoxin reductase (E.C 1.6.4.5.; TrxR), thioredoxin (Trx) and nicotinamide adenine dinucleotide phosphate (NADPH), and participates in cell growth, apoptosis, antioxidant defense, redox signaling, etc. In this study, cytoplasmic TrxR enzyme was purified by using heat denaturation and 2',5'-ADP Sepharose 4B affinity chromatograph techniques from rainbow trout gill tissues. The purity and the monomer molecular weight of the enzyme were determined with SDS-PAGE. KM values for NADPH and 5,5'-Dithiobis (2-nitrobenzoic acid), the substrates of the enzyme were calculated by means of Lineweaver-Burk graphic. Optimal pH and optimal ionic strength values were determined as 7.75 and 300 mM, respectively. Then, in vitro effects of the Ni2+, Cu2+, Pb2+, Cd2+, Sr2+, Zn2+, Mg2+, Cr3+, Fe3+, Al3+ and Ag+ metal ions on the enzyme activity were analyzed. IC50 values were determined for the ones showing inhibition effect and their Ki values were calculated by means of Cheng-Prusoff equation.