CRYSTAL STRUCTURE OF INFLUENZA VIRUS NEURAMINIDASE WITH INHIBITOR 3,5-DIGUANIDINO-4-(N-ACETYLAMINO)BENZOIC ACID E. A. Sudbeck,¹ M. J. Jedrzejas,^1,2 S. Singh,³ W. J. Brouillette,³ G. M. Air,² W. G. Laver,⁴ Y. S. Babu,⁵ S. Bantia,⁵ P. Chand,⁵ N. Chu,⁵ J. A. Montgomery,⁵ D. A. Walsh,⁵ M. Luo,^{l,2 1}Center for Macromolecular Crystallography, ²Department of Microbiology, ³Department of Chemistry, University of Alabama, Birmingham, AL, ⁴John Curtin School of Medical Research, Australian National University, Canberra, Australia, ⁵BioCryst Pharmaceuticals, Inc., Birmingham, AL.

We have designed a series of benzoic acid derivatives to fit into the active site of influenza virus neuraminidase and inhibit its enzymatic activity. Because the residues in the active site of neuraminidase are conserved for all known strains of influenza virus, these types of inhibitors have a potential to be highly effective drugs against the virus. One such compound, 3,5-diguanidino-4-(N-acetylamino)benzoic acid (1), shows measurable inhibition of neuraminidase in activity assays. We have solved the X-ray crystal structure of B/Lee/40 neuraminidase complexed with 1 at -180deg.C and 2.2Å resolution. The inhibitor interacts with amino acid residues in the active site of neuraminidase through specific hydrogen bonds and hydrophobic interactions. The structure is compared to the complex of neuraminidase with a related inhibitor, 3-guanidino-4-(N-acetyl-amino)benzoic acid (2). Compounds 1 and 2 interact similarly in the active site of neuraminidase except for a displacement of two structural water molecules by the 5-guanidino group of 1.