Differential effects of ethanol on membrane-bound and soluble acetylcholinesterase from sarcoplasmic reticulum membranes.
The action of ethanol on the activity of membrane-bound and soluble acetylcholinesterase (AChE) in sarcoplasmic reticulum of skeletal muscle has been studied. Treatment of membranes with 2.5-12.5% v/v ethanol produced a slight stimulation of the AChE activity and inhibition at higher concentration. The enzyme remained associated with the membranes after these treatments. The enzyme solubilized with Triton X-100 was inhibited by ethanol in a time-independent manner. Isolated 16 S (A12), 10.5 S (G4) and 4.5 S (G1) forms of AChE were inhibited by ethanol to a similar extent. Samples were reversibly inhibited by ethanol, up to 12.5% v/v, and irreversibly at higher concentrations. Kinetic studies performed with isolated forms in the presence of 5-12.5% v/v ethanol showed that the solvent behaved as a competitive inhibitor of the asymmetric form but as a mixed inhibitor of the tetrameric and monomeric forms. The results show that the solvent interacts with active and/or regulatory sites of AChE from muscle microsomes.
Cabezas-Herrera
J
J
Departamento de Bioquímica y Biología Molecular, Universidad de Murcia, Spain.
Campoy
F J
FJ
Vidal
C J
CJ
D000110:Acetylcholinesterase / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D000431:Ethanol / Q000494:pharmacology*; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000201:enzymology*
D000431:Ethanol; D000110:Acetylcholinesterase