Chiral recognition study for the inclusion complexes of amino acids with α-cyclodextrin using a fast annealing evolutionary algorithm

Molecular interactions of inclusion complexes of amino acids and alpha -cyclodextrin have been studied by a fast annealing evolutionary algorithm (FAEA) in this paper. Using the consistent force field (CFF91), the non-bonded energies between all pairs of atoms mi different molecules were determined by a Coulomb potential term for electrostatic interactions and a Lennard-Jones potential for van der Waals interactions. The total interaction energies for 14 inclusion complexes with experimental association constants (In K) were optimized by the FAEA method. Linear regression analysis of the observed association constants against the total energies was performed. The result indicated that there is an extremely good correlation between ln K and the total interaction energies. Furthermore, by analyzing each energy term, the van der Waals term is the major contributor to the total energies and the electrostatic force is also important in inclusion complexation. In the 14 inclusion complexes, four pairs of L-/D-amino acids were compared. The interaction energies of alpha -cyclodextrin with the L-amino acids are lower than the energies with the D-enantiomers. It is in agreement with the experimental results. The enantioselectivity can, therefore, be calculated from the complexation energies of L-/D-amino acids. (C) 2001 Elsevier Science B.V. All rights reserved.