The assessment of cholinesterase from the liver of Anabas testudineus for detection of metal ions

Climbing Perch or its scientific name, Anabas testudineus is classified as one of the freshwater fishes belonging to the family of Anabantidae. It is locally known as „Ikan Puyu‟ and is widely distributed in ponds, swamps and estuaries in Asia. In this study, cholinesterase (ChE) was partially purified from the liver of A. testudineus through ion exchange chromatography. This purification method provided recovery yield of 5.35% with a purification fold of 6.6. The optimum conditions for ChE assay were identified to be 2.5 mM butyrylthiocholine iodide (BTC) with pH 8.0 in 0.1 M Tris-HCl buffer at 40°C. Substrate specificity profile also indicated that ChE favours BTC as substrate because it records the highest catalytic efficiency (Vmax/Km). Metal ion inhibition tests were conducted and mercury (Hg) was found to show the highest inhibition effect (87.30%) whereas lead (Pb) showed the lowest inhibition effect (28.01%). The half maximal inhibitory concentration (IC50) value of mercury for partially purified ChE was 0.071 ppm. Result obtained from protein analysis through Native-PAGE has shown ion exchange chromatography as an effective method in partially purified ChE. All these findings showed that partially purified ChE from the liver of A. testudineus is suitable to be used as a bioindicator to detect the presence of metal ions.

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