ISSN:
0899-0042
Keywords:
affinity
;
efficacy
;
dissociation
;
constants
;
steroselectivity
;
entropy
;
enthalpy
;
receptor
;
interaction
;
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
After alkylation of a fraction of the total α-adrenoreceptors by phenoxybenzamine in rat vas deferens, the dissociation constants of (-)- and (+)-epinephrine in functional studies were 7 × 10-7 M and 2 × 10-5 M, respectively. In the adrenoreceptor-containing tissue fraction, when 3H-labeled WB4101 was used as the interacting ligand, for each enantiomer who affinity sites were found. Only the low-affinity dissociation consant for each isomer correlates with the constant obtained from the functional studies. If the change in Gibb's free energy. ΔG°, is calculated from the low-affinity binding constants, the values -8.1 and -6.2 kcal/mol for (-)- and (+)-isomer, respectively, are obained. The small difference in the value between isomers forms a hydrogen bond with the receptor. The interaction of epinephrine with this receptor appears to be driven largely by the entropy of the drug-receptor interaction with only a small nonsteroselective contribution from the enthalpy of ineraction.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/chir.530010106