Accession Number : AD0745227

Title :   Relative Binding Sites of Pharmacologically Active Ligands on Bovine Erythrocyte Acetylcholinesterase,

Corporate Author : BRITISH COLUMBIA UNIV VANCOUVER FACULTY OF PHARMACEUTICAL SCIENCES

Personal Author(s) : Roufogalis,B. D. ; Quist,E. E.

Report Date : 09 AUG 1971

Pagination or Media Count : 9

Abstract : The kinetics of the interaction of partially purified bovine erythrocyte acetylcholinesterase (EC 3.1.1.7) with calcium, tetramethylammonium, tetraethylammonium, decamethonium, gallamine, and d-tubocurarine has been investigated, using acetylcholine as substrate. Antagonism between various combinations of ligands has been studied. Decamethonium binds to the catalytic anionic site (alpha) and to an allosteric site (beta). Calcium (0.2mM) competes with decamethonium but not with acetylcholine, and is considered to act at the beta-anionic site. Neither tetramethylammonium, tetraethylammonium, nor calcium antagonizes the binding of gallamine. This observation, together with that of the partially competitive nature of the inhibition by gallamine, indicates that gallamine cannot bind to the alpha- or beta-anionic sites and hence must bind to a second allosteric site, gamma. The ability of gallamine to antagonize inhibition by decamethonium is attributed to allosteric perturbations of the alpha- and beta-sites induced by the action of gallamine at the gamma-site. (Author)

Descriptors :   (*ACETYLCHOLINESTERASE, CHEMICAL BONDS), (*ENZYMES, PHARMACOLOGY), IONS, CHEMICAL REACTIONS, ERYTHROCYTES, SKELETAL MUSCLE RELAXANTS, MOLECULAR ASSOCIATION

Subject Categories : Pharmacology

Distribution Statement : APPROVED FOR PUBLIC RELEASE