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Structural requirements at the melatonin receptor
Author(s) -
Sugden David,
Chong Nelson W.S.,
Lewis David F.V.
Publication year - 1995
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1995.tb17184.x
Subject(s) - melatonin , melatonin receptor , binding site , amino acid , receptor , stereochemistry , agonist , chemistry , ligand (biochemistry) , biology , biochemistry , endocrinology
1 High affinity, specific binding sites for the pineal hormone, melatonin (5‐methoxy N ‐acetyltryptamine) can be detected in chick brain membranes by use of the radiolabeled agonist, 2‐[ 125 I]‐iodomelatonin (2‐[ 125 I]‐aMT). 2 The affinity of a number of analogues of melatonin at the 2‐[ 125 I]‐aMT binding site was determined and compared with an analysis of their electronic structure and significant quantitative relationships obtained. 3 The best correlations indicated that binding affinity was correlated with ΔE, the difference between the frontier orbital energies, and Q N H, the electron density in the highest occupied molecular orbital of the side‐chain nitrogen atom. 4 These findings suggest that ligand binding may involve hydrogen bonding between the 5‐methoxy and amide moieties of melatonin and complementary amino acid residues, and charge transfer interactions between the indole ring of melatonin and an aromatic amino acid in the receptor binding site. 5 A molecular model of a putative binding site is proposed based on the predicted amino acid sequence of the cloned Xenopus laevis melanophore melatonin receptor and the quantitative structure‐affinity relationships observed in the present study.