Kinetics of human and horse sera cholinesterases inhibition with solanaceous glycoalkaloids: Study by potentiometric biosensor

The kinetics of inhibition of human and horse sera butyryl cholinesterases by solanaceous glycoalkaloids alpha-solanine, alpha-chaconine and tomatine has been studied by means of a potentiometric biosensor based on pH-sensitive field effect transistors (pH-FETs). Using acetyl-and butyryl choline as substrates, the optimal pH and the apparent kinetic parameters (K-mapp, V-maxapp) of immobilized cholinesterases have been calculated in the absence of inhibitors. All studied glycoalkaloids were reversible inhibitors of both butyryl cholinesterases, and inhibited the horse and human immobilized enzymes in competitive and mixed modes, respectively, The affinity of each enzyme towards alpha-solanine, alpha-chaconine and tomatine has been estimated through calculation of apparent inhibition constants K-iapp and inhibition coefficients I-50. An application of the butyryl cholinesterases studied in the biosensors for glycoalkaloids determination in the concentration range of 10(-7) to 10(-4) M has been discussed. (c) 2006 Elsevier Inc. All rights reserved.