Premium
Kinetics of the inhibition of acetylcholinesterase from pigeon brain by procaine hydrochloride
Author(s) -
AlJafari Abdulaziz A.,
Duhaiman Ali S.
Publication year - 1994
Publication title -
cell biochemistry and function
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.933
H-Index - 61
eISSN - 1099-0844
pISSN - 0263-6484
DOI - 10.1002/cbf.290120309
Subject(s) - acetylthiocholine , chemistry , procaine hydrochloride , acetylcholinesterase , procaine , aché , hydrochloride , non competitive inhibition , kinetics , michaelis–menten kinetics , nuclear chemistry , iodide , hydrolysis , reaction rate constant , stereochemistry , chromatography , enzyme , medicinal chemistry , enzyme assay , biochemistry , organic chemistry , pharmacology , biology , physics , quantum mechanics
The kinetic parameters of the inhibition of pigeon brain acetylchlolinesterase (AChE) by procaine hydrochloride were investigated. Procaine (0·083–1·67 mM) reversibly inhibited AChE activity (15–83 percent) in a concentration dependent manner, the IC 50 being about 0·38 mM. The Michaelis‐Menten constant ( K m ) for the hydrolysis of acetylthiocholine iodide was found to be 1·53 × 10 −4 M and the V max was 1·06 μmol min −1 mg −1 protein. Dixon as well as Lineweaver‐Burk plots and their secondary replots indicated that the nature of the inhibition is of the linear mixed type which is considered to be a mixture of partial competitive and pure non‐competitive. The values of K i(slope) and K i (intercepts) were estimated as 0·14 mM and 0·22 mM respectively by the primary Dixon and by the secondary replots of the Lineweaver‐Burk plot. The K i ′/ K i ratio shows that procaine has a greater affinity of binding for the peripheral than for the active site.