Kinetics of N-methylscopolamine interaction with muscarinic receptor from rat cerebral cortex.
Kinetics of binding of tritiated N-methylscopolamine with muscarinic receptor from rat cerebral cortex and kinetics of dissociation of this receptor-ligand complex were studied at 25 degrees C. The plot of the observed association rate constants vs the ligand concentration was hyperbolic, giving evidence of a two-step binding mechanism involving a fast complex formation step followed by slow monomolecular isomerization of this receptor-antagonist complex RA into (RA). The dissociation reaction of N-methylscopolamine from its complex with muscarinic receptor was described by the rate equation consisting of two exponential terms and pointing to the possibility of further isomerization of the complex (RA) into [(RA)] according to the reaction scheme: [Formula: see text] . The latter isomerization step is slow in comparison with the first one. The data are discussed with reference to the kinetic mechanism of the receptor ligand interaction.
Eller
M
M
Laboratory of Enzymology and Laboratory of Bioorganic Chemistry, Tartu State University, 202400 Tartu, Estonian SSR, U.S.S.R.
Järv
J
J