Abstract
The structure of the complex between cyclophilin and cyclosporin A is predicted by combining X-ray crystallographic and NMR spectroscopic data using molecular modeling. The drug was placed at the receptor site using a directed docking procedure in which an impulse is imparted to a pre-oriented ligand along an established path. Both ligand and receptor atoms are flexible during the procedure. Two conformers of the MeBMT side chain are shown to result in similar ligand-receptor interaction energies. The models for the drug-receptor complex appear consistent with known experimental data and provide a significant opportunity for the design of compounds with enhanced therapeutic value.