Vol. 54, Issue 1, 129-138, July 1998

Ligand Specificity of the Genetic Variants of Human ₁-Acid Glycoprotein: Generation of a Three-Dimensional Quantitative Structure-Activity Relationship Model for Drug Binding to the A Variant

Françoise Hervé, Giulia Caron, Jean-Claude Duché, Patrick Gaillard, Noorsaadah Abd. Rahman,¹ Anna Tsantili-Kakoulidou, Pierre-Alain Carrupt, Philippe d'Athis, Jean-Paul Tillement, and Bernard Testa

Service Hospitalo-Universitaire de Pharmacologie de Paris XII, Centre Hospitalier Intercommunal de Créteil, F-94010 Créteil Cedex, France (F.H., J.-C.D., J.-P.T.), Institut de Chimie Thérapeutique Section de Pharmacie, Université de Lausanne, CH-1015 Lausanne-Dorigny, Switzerland (G.C., P.G., N.A.R., A.T.-K., P.-A.C., B.T.), and Laboratoire d'Informatique Médicale, Faculté de Médecine de Dijon, F-21033 Dijon Cedex, France (P.d'A.)

Human ₁-acid glycoprotein (AAG) is a mixture of at least two genetic variants: the A variant and the F1 and/or S variant or variants, which are encoded by two different genes. In a continuation of previous studies indicating specific drug transport roles for each AAG variant according to its separate genetic origin, this work was designed to (1) determine the affinities of the two main gene products of AAG (i.e., the A variant and a mixture of the F1 and S variants) for 35 chemically diverse drugs and (2) to obtain meaningful 3D-QSARs for each binding site. Affinities were obtained by displacement experiments, leading to qualitative indications about binding site characteristics. In particular, drugs binding selectively to the A variant displayed some common structural features, but this was not seen for the F1*S variants. Three-dimensional QSAR analyses using the CoMFA method yielded a steric model for binding to the A variant, from which a simplified haptophoric model was derived. In contrast, no statistically sound model was found for the F1*S variants, possibly due (among other reasons) to an insufficient number of high affinity ligands in the set.