Abstract:

A new method which can estimate the binding affinity of an enzyme-ligand complex was applied to studying the inhibitors of thrombin. The three-dimensional structures of thrombininhibitor complexes were modeled from the crystalline structures of template compounds. Program SCORE was then used to predict the binding affinities of the complexes. Altogether 34 inhibitors of three series were analyzed. The calculated dissociation constants correlated well with the experimentally determined values. This result is much better than the ones given by standard molecular mechanics. By comparing the structures and the binding affinities of two inhibitors, it was demonstrated that this method could measure the contribution of each part of a ligand quantitatively and in turn give explicit structrue-activity relationships.

Key words: Thrombin inhibitor, Binding affinity, Structure-based quantitative structure-activity relationship, Drug design