MATERIALS AND METHODS
Cloning, expression, and purification. PAN, covering residues 1 to 256, was
cloned from an avian influenza A virus isolate [A/goose/Guangdong/1/96 (H5N1)],
as described previously (23).
Crystallization and diffraction data collection. Crystals of a form of the influenza
virus PAN containing the N-terminal 256 residues were grown, as described
previously (23). Crystals were soaked for 25 to 30 days at 16°C in a solution
containing either rGMP, rUMP, rAMP, TMP, or rCMP at the concentration of