This study reports on the characterization of a purified AChE from Oreochromis mossambica
brain extract. The purification protocol involved the application of custom-synthesized affinity
chromatography gel (Edrophonium–Sephacryl S-400) and the use of high performance liquid
chromatography system (HPLC). Soluble AChE was partially purified 27.9 fold with a highest
specific activity around 73.1 × 103 U/mg proteins. The partially purified AChE higher capability
to hydrolyse acetylthiocholine (ATC) and shows less degradation against propionylthiocholine
(PTC) and also butyrylthiocholine (BTC). Based on enzyme kinetic analysis, the partially
purified AChE exhibits the apparent Michaelis constants Km, for ATC, PTC and BTC in the
range of 125, 260 and 600 μM and the maximum velocities Vmax were 276, 59 and 36
μmol/min/mg protein, respectively. The apparent inhibition constant (ki) values of eserine,
propidium and carbofuran were 0.24 μM-1min-1, 65 μM-1min-1 and 0.41 μM-1min-1 μM-1min-1,
respectively. The purified enzyme is apparently an AChE since it capable to hydrolyzes ATC at a
higher rate compared to other synthetic substrates, at pH 7.0 and 25ºC, and is inhibited by it
specific inhibitor which is eserine but not by iso-OMPA.