Acetylcholinesterase from desert Cobra (Walterinnesia aegyptia) venom: Optimization and kinetics study |
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Authors: | Abdulaziz A. AlJafari M. A. Kamal Ali S. Duhaiman A. S. Alhomida |
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Affiliation: | (1) Department of Biochemistry, College of Science, King Saud University, P.O.Box 2455, 11451 Riyadh, Saudi Arabia |
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Abstract: | Acetylcholinesterase (AChE) was investigated inWalterinnesia aegyptia venom and characterized with respect to its kinetic properties. It was found that 4.0 ug of crude venom protein and an incubation time of 4.0 min were suitable conditions for linearity of AChE activity at 25°C. The optimum strength of the sodium phosphate buffer was 0.05 M, and the optimum pH was 7.75. The optimum temperature was 30°C. The activation energy and the heat of activation were observed to be 6510 and 5922 cal/mole. The AChE was specific for acetylthiocholine but it did not hydrolyse butyrylthiocholine. The optimum substrate concentration was 3.0 mM but at higher substrate concentrations, the AChE activity declined. The ASCh concentration ranges for different orders of the reactions were determined and kinetic parameters (Km, Vmax, kcat, and ksp) were established at each order of the reaction.Abbreviations AChE acetylcholinesterase - ASCh acetylthiocholine - Km Michaelis-Menten constant - Vmax the limiting maximal velocity - AChEa acylated enzyme - kcat turnover number - ksp specificity constant |
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Keywords: | acetylcholinesterase optimization kinetics venom turnover number |
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