Differential effects of ethanol on membrane-bound and soluble acetylcholinesterase from sarcoplasmic reticulum membranes |
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Authors: | Juan Cabezas-Herrera Francisco J Campoy Cecilio J Vidal |
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Institution: | (1) Departamento de Bioquímica y Biología Molecular. Lab B. 1. Edificío de Veterinaria, Universidad de Murcia, 30071 Murcia, Spain |
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Abstract: | 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. |
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Keywords: | Acetylcholinesterase molecular forms ethanol muscle microsomes |
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