YETI: An interactive molecular mechanics program for small‐molecule protein complexes

YETI, an interactive molecular mechanics program for drug‐design applications on small‐molecule protein complexes, is described. To model short‐range interactions in better agreement with experimental data, its force‐field energy expression includes directional potential functions for H‐bonds, salt linkages, and metal ligand interactions. The program works on an internal coordinate concept and uses a conjugate‐gradient minimizer. YETI is available for distribution through the author. The program has been used to model details of small‐molecule binding to the enzyme human carbonic anhydrase I. The impact of the directional potential functions on the geometry of H‐bonds and metal‐ligand interactions is discussed.