Abstract
We studied the stereoselective interaction between aryloxypropanolamines and the human 5-hydroxytryptamine1A(5-HT1A) receptor. R- andS-enantiomers of propranolol, penbutolol, and alprenolol were investigated for their ability to bind to human 5-HT1Awild-type and Asn386Val mutant receptors. Asn386 seemed to act as a chiral discriminator. Although both aryloxypropanol enantiomers displayed lower affinity for the mutant receptors, the affinities for the S-enantiomers were more affected. Receptor affinities of other structurally unrelated 5-HT1A ligands were not decreased by the mutation of Asn386 to valine. In addition, a series of analogues of propranolol with structural variation in the oxypropanolamine moiety was synthesized, and affinities for wild-type and Asn386Val mutant 5-HT1A receptors were determined. Both the hydroxyl and the ether oxygen atoms of the oxypropanol moiety seem to be required for binding at wild-type 5-HT1A receptors. The hydroxyl group of propranolol probably directly interacts with Asn386. The ether oxygen atom may be important for steric reasons but can also be involved in a direct interaction with Asn386. These findings are in agreement with the interactions of aryloxypropanolamines with Asn386 in rat 5-HT1A receptors that we previously proposed. The loss of affinity for propranolol by the Asn386Val mutation could be regained by replacement of the hydroxyl group of the ligand by a methoxy group. This modification of the propranolol structure has no effect on the affinity of both enantiomers for the wild-type 5-HT1A receptor, which provides an alternative hypothesis for the interaction of Asn386 with the oxypropanol oxygen atoms. According to this novel hypothesis, the oxypropanol oxygen atoms may both act as hydrogen bond acceptors from the NH2 group of Asn386.
Footnotes
- Received November 4, 1996.
- Accepted January 28, 1997.
-
Send reprint requests to: Dr. W. Kuipers, Department of Medicinal Chemistry, Solvay Pharmaceuticals Research Laboratories, P.O. Box 900, 1380 DA Weesp, The Netherlands. E-mail:kuipers-solvay{at}e-mail.com
-
The research of R. Leurs has been made possible by a fellowship of the Royal Netherlands Academy of Arts and Sciences.
- The American Society for Pharmacology and Experimental Therapeutics
MolPharm articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|