Purification of carbonic anhydrase from the gill tissue of rainbow trout (Oncorhynchus mykiss) inhabiting the Harşit Stream (Gümüşhane, Türkiye) and investigation of the inhibitory effects of some heavy metals on enzyme activity

In this study, carbonic anhydrase (carbonate hydro-lyase, EC 4.2.1.1) was purified from the gill tissue of rainbow trout (Oncorhynchus mykiss), and the inhibitory effects of several heavy metals on enzyme activity were investigated. The purification procedure involved preparing a gill homogenate, followed by affinity chromatography and subsequent elution of the enzyme. Carbonic anhydrase (CA) was purified from the gill tissue of Oncorhynchus mykiss with a purification yield of 25.1%. The purity of the enzyme was confirmed by sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE), which revealed a single protein band. The inhibitory effects of several metal ions on CA activity were also evaluated. For this purpose, Al, Sr, Ca, Hg, Mn, Fe, Ba, Mg, Zn, and Cu were used as inhibitors. All tested metal ions exhibited inhibitory effects on carbonic anhydrase activity. The IC₅₀ values of the metal ions were determined from plots of residual enzyme activity (%) versus inhibitor concentration ([I]). The IC₅₀ values for Al, Sr, Ca, Hg, Mn, Fe, Ba, Mg, Zn, and Cu were determined to be 0.0047, 0.015, 0.039, 0.0097, 0.022, 0.012, 0.0085, 0.020, 0.0063, and 0.011 mM, respectively.