Thermodynamic analysis of isoproterenol binding to beta-adrenoceptors in rat lung membranes.
The thermodynamic properties of the binding of the beta-adrenoceptor agonist isoproterenol and of the antagonist propranolol to beta-adrenoceptors of rat lung were investigated. We found that in our experimental conditions, the high- and low-affinity binding sites for the agonist displayed different properties: the binding to the high-affinity binding site was entropy-driven with a small increase in enthalpy, while agonist binding to the low-affinity binding site was enthalpy-driven. Binding of isoproterenol in the presence of GTP or its non-hydrolyzable analogue GppNHp, and the binding of propranolol were enthalpy-driven with a small increase in entropy.
Fraeyman
N
N
Heymans Institute of Pharmacology, University of Gent, Medical School, Belgium.
Bazan
A
A
Vanscheeuwijck
P
P
D000818:Animals; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000378:metabolism*; D008168:Lung / Q000187:drug effects*; D008297:Male; D011433:Propranolol / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D013816:Thermodynamics
D011943:Receptors, Adrenergic, beta; D011433:Propranolol; D007545:Isoproterenol