Structure–activity relationship studies of a bisbenzimidazole-based, Zn2+-dependent inhibitor of HCV NS3 serine protease

A survey of isosteric replacements of the phosphonoalanine side chain coupled with a process of conformational constraint of a bisbenzimidazole-based, Zn2+-dependent inhibitor of hepatitis C virus (HCV) NS3 serine protease resulted in the identification of novel series of active compounds with extended side chains. However, Zn2+-dependent HCV NS3 inhibition was relatively insensitive to the structural variations examined but dependent on the presence of negatively charged functionality. This result was interpreted in the context of an initial electrostatic interaction between protease and inhibitor that is subsequently consolidated by Zn2+, with binding facilitated by the featureless active site and proximal regions of the HCV NS3 protein.