Elsevier

Biochemical Pharmacology

Volume 18, Issue 9, September 1969, Pages 2153-2161
Biochemical Pharmacology

Apparent dissociation constants for several inhibitors of acetylcholinesterase in the intact electroplax of the electric EEL

https://doi.org/10.1016/0006-2952(69)90320-7Get rights and content

Abstract

Apparent dissociation constants were determined for d-tubocurarine, benzoquinonium, ambenonium, WIN 3286, and WIN 7789 as inhibitors of acetylcholinesterase (AChE) in the intact electroplax of Electrophorus electricus. These five compounds showed nearly the same order of potency for inhibiting AChE in intact electroplax cells as had been determined earlier using AChE purified from the electric organ of the electric eel. However, the constants were 140–510 times higher for cellular AChE than for purified AChE. The order of effectiveness of these five compounds as inhibitors of cellular AChE was completely different from the order previously determined for inhibition of the acetylcholine receptor of the intact electroplax of the electric eel. The ratio of the apparent dissociation constants determined for cellular AChE compared to the constants for the acetylcholine receptor varied from 0.16 to 3500. It is concluded that the active site of AChE is different from that of the acetylcholine receptor.

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    This work was supported by U.S.P.H.S. Grant NBO7265.

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