Novel aromatic inhibitors of influenza virus neuraminidase make selective interactions with conserved residues and water molecules in the active site

The active site of type A or B influenza virus neuraminidase is composed of 11 conserved residues that directly interact with the substrate, sialic ac id. An aromatic benzene ring has been used to replace the pyranose of siali c acid in our design of novel neuraminidase inhibitors. A bis(hydroxymethyl )pyrrolidinone ring was constructed in place of the N-acetyl group on the s ialic acid. The hydroxymethyl groups replace two active site water molecule s, which resulted in the high affinity of the nanomolar inhibitors. However , these inhibitors have greater potency for type A influenza virus than for type B influenza virus. To resolve the differences, we determined the X-ra y crystal structure of three benzoic acid substituted inhibitors bound to t he active site of B/Lee/40 neuraminidase. The investigation of a hydrophobi c aliphatic group and a hydrophilic guanidino group on the aromatic inhibit ors shows changes in the interaction with the active site residue Glu275. T he results provide an explanation for the difference in efficacy of these i nhibitors against types A and B viruses, even though the 11 active site res idues of the neuraminidase are conserved. (C) 1999 Academic Press.