Electrochemical Approach in Studying the Inactivation of Immobilized Acetylcholinesterase by Arsenate(III)

An acetylcholinesterase amperometric sensor is used to register the current of oxidation of thiocholine, the product of the acetylcholinesterase catalyzed hydrolysis of acetylthiocholine. The decrease of the value of the signal obtained in presence of arsenate(III) is interpreted as due to the diminution of the quantity of the generated thiocholine because of the inhibition of the immobilized acetylcholinesterase on the surface of a graphite electrode. The experiments were performed varying the concentrations of the inhibitor and of the substrate, as well as pH. The kinetics of the inactivation of the immobilized acetylcholinesterase by arsenate(III) was investigated. Obtained results could be employed for the quantitative determination of AsO33− based on the inhibition of the immobilized acetylcholinesterase on the surface of a graphite electrode, using an electrochemical approach.