Structural Studies on Intact Clostridium Botulinum Neurotoxins Complexed With Inhibitors Leading to Drug Design

摘要

In this first annual report we present our progress in three of the Statement of Work. In addition we have included our work being done in collaboration with Walter Reed Army - Institute of Research. Structural work with Clostridium botulinum B and a potential inhibitor, SABIM, is reported. Though it was predicted that it would bind to the active site, we have shown that it binds at two sites in BoNT/B, the active site and the substrate-binding site. We speculate that the inhibitory property of this molecule may be because it chelates the active site zinc or because it blocks the substrate binding site or due to both. We also propose that analogs of BABIM might work better. We are continuing with our studies on BoNT/B with other potential inhibitors. A set of potential inhibitors identified by biochemical methods and a few small molecules known to inhibit zinc - endopeptidases like thermolysin and carboxypeptidase have been screened by computational methods before determining the structures of the complexes. Combining the docking calculations with the x-ray diffraction methods offers a powerful rational design of inhibitors. From our studies so far we conclude that small molecules that will stay bound to the toxins will%be the best inhibitors.