4-AMINOPHENYL ACETATE AS A SUBSTRATE FOR AMPEROMETRIC ESTERASE SENSORS

4-Aminophenyl acetate (PAPA) was applied as a new substrate for esterase activities. Acetylcholinesterase from electric eel (EC 3.1.1.7) was determined using PAPA as an improved substrate. Acetylcholinesterase was covalently bound to a nylon filter mesh using glutaraldehyde and bovine serum albumin as cross-linkers. The modified membrane was subsequently attached to the surface of a glassy carbon electrode. 4-Aminophenol generated by the enzymatic reaction was detected by cyclic voltammetry and amperometry at an activated glassy carbon electrode. A linear current response, proportional to the PAPA concentration, over the range 0.1 muM-0.5 mM was obtained. Optimization of various kinetic parameters of the biosensor is discussed. Acetylcholinesterase was determined in whole human blood using PAPA as substrate.