Puri cation and characterization of mitochondrial thioredoxin reductase enzymefrom rainbow trout (Oncorhynchus mykiss) liver and investigation of the in vitroeffects of some metal ions on the enzyme

Abstract

Thioredoxin reductase (E.C 1.6.4.5.; TrxR) is an enzyme belonging to the avoprotein family of pyridinenucleotide-disul de oxidoreductases. In this study, mitochondrial TrxR enzyme was puri ed from rainbow trout mi-tochondria. Thanks to the 2 consecutive procedures (preparation of homogenate and 2',5'-ADP Sepharose 4B affinitychromatography), the enzyme, having the speci c activity of 11.9 EU mg protein-1, was puri ed with a yield of 2.38%and 672-fold. The purity of the enzyme was monitored and the molecular weight of its subunits was calculated as 70kDa by SDS-PAGE. The native molecular mass of the enzyme was found to be approximately 151 kDa by gel ltrationchromatography. Characteristic and kinetic properties of the enzyme were also determined. Furthermore, Se4+, Cu2+,Co2+, Ni2+, Fe3+, and Al3+metal ions' in vitro effects on mitochondrial TrxR puri ed from rainbow trout was investi-gated. While Se4+ion increased the enzyme activity, all of the other metal ions used in this study showed an inhibitoryeffect.