INFLUENZA B/LEE/40 NEURAMINIDASE: X-RAY STRUCTURE OF ENZYME COMPLEXED WITH 4-GUANIDINO-Neu5ac2en. N. Y. Chirgadze, J. M. Colacino, K. A. Staschke, K. Briner, W. J. Hornback, J. E. Munroe, R. Loncharich, W. G. Laver^*, Lilly Research Laboratories, Indianapolis, IN. USA, ^*The Australian National University, Canberra, Australia

Neuraminidase from influenza B/Lee/40 was crystallized and complexed with the potent and selective influenza neuraminidase inhibitor, 4-guanidino-Neu5Ac2en¹, by soaking the crystal in a concentrated solution of the inhibitor. Crystals suitable for X-ray have been obtained from PEG. They belong to tetragonal P42₁2 space group containing one subunit per asymmetric unit. The enzyme-inhibitor complex crystal structure was determined by X-ray technique. An experimental data has been collected up to 2.8 Å resolution with an R_merge Of 10.4%. The crystal structure has been refined using a molecular dynamic procedure to yield a current crystallographic R-factor of 16%. The electron density of the inhibitor in the active site is well-defined and interpretation of the electron density distribution reveals an interaction between the C-4 guanidinium moiety of the inhibitor with the glutamic acid at position 117 which lies within a pocket of the active site of the neuraminidase. Similar results have been obtained using influenza A N9 neuraminidase². Computational techniques are being used to analyze the enzyme-inhibitor interaction in terms of H-bond strengths.

[1] von Itzstein M. et al. (1993) Nature 363:418-423.

[2] Varghese et al. (1995) Protein Sci. 4:1081-1087.