Author/Editor		Goličnik, Marko; Stojan, Jure
Title		Transient kinetic approach to the study of acetylcholinesterase reversible inhibition by eseroline
Type		članek
Source		In: Parveen M, Kumar S, editors. Recent trends in the acetylcholinesterase system. Amsterdam: IOS Press,
Publication year		2005
Volume		str. 77-89
Language		eng
Abstract		The kinetic rate constants for interaction of (-)-eseroline- (3aS-cis)-1,2,3,3a,8,8a-hexahydro-1,3a,8-trimethylpyrrolo-(2,3-b) indol-5-o1 with electric eel acetylccholinesterase (EC 3.1.1.7, acetylcholine acetylhydrolase) were measured at a low substrate concentration according to a transient kinetic approach by using a rapid experimental technique. The measurements were carried out on a stopped-flow apparatus where pre-incubated samples of enzyme with various inhibitor concentrations were diluted with a buffer solution containing the substrate. The experimental data in the form of sigmoid curves were analysed by applying an explicit progress curve equation that described the time dependence of product released during the reaction. The kinetic parameters were evaluated by non-linear regression treatment and the values of the corresponding constants showed approximately the equal affinities of esoroline and eserine (Stojan and Zorko 1997) for binding into the active center of the enzyme. On the other hand, the kinetic rates for association and dissociation of eseroline were two grades of magnitude higher than those of eserine. The explanation appears to be a substantially impaired gliding of eserine into the active site gorge by the great mobility of the carbamoyl tail as well as by its numerous possible interactions with the residues lining the gorge. Additionally, a study of the dependence of the transition phase information on the inhibitor concentration was carried out using our experimental data.
Descriptors		ACETYLCHOLINESTERASE CHOLINESTERASE INHIBITORS KINETICS ELECTROPHORUS PHYSOSTIGMINE BINDING SITES ACETYLTHIOCHOLINE HYDROLYSIS