On the inhibition of camel retina acetylcholinesterase activity by cycloheximide in vitro.
The kinetic parameters of inhibition of camel retinal acetylcholinesterase (AChE) activity by cycloheximide (CH) were investigated. For the control system, the Michaelis-Menten constant (K(m)) for the hydrolysis of acetylthiocholine iodide was found to be 0.076 mmol/L and the Vmax was 0.547 mumol/min per mg protein. In contrast, these parameters were decreased in the CH-treated systems. Dixon and Lineweaver-Burk plots, and their secondary replots, indicated that the inhibition was of the linear mixed type, which seems to be a combination of partial competitive and pure noncompetitive inhibition. The values of K'i(slope) and KI(intercept) were estimated to be 3.50 and 5.68 mmol/L, respectively. Ki was greater than K'i, indicating that CH has a greater binding affinity for the peripheral site than the active site.
al-Jafari
A A
AA
Department of Biochemistry, College of Science, King Saud University, Riyadh, Saudi Arabia.
Kamal
M A
MA
Alhomida
A S
AS
D000109:Acetylcholine / Q000378:metabolism; D000110:Acetylcholinesterase / Q000378:metabolism*; D000818:Animals; D002162:Camelus; D002800:Cholinesterase Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D003513:Cycloheximide / Q000737:chemistry / Q000494:pharmacology*; D015394:Molecular Structure; D012160:Retina / Q000201:enzymology*
D002800:Cholinesterase Inhibitors; D003513:Cycloheximide; D000110:Acetylcholinesterase; D000109:Acetylcholine