Crystals of a fragment of influenza haemagglutinin in the low pH induced conformation.

Fusion of the influenza viral membrane with the membrane of the host cell is preceded by a low pH induced conformation change in the viral haemagglutinin. A fragment, consisting of much of the stem domain of influenza haemagglutinin in the low pH induced conformation, has been crystallized by the vapour diffusion method. Several crystal forms have been obtained and the molecular packing in these crystals is discussed. Crystals suitable for the recording of high angle X-ray diffraction data grow in space group C222(1). Diffraction data have been recorded from crystals cooled to -170 degrees C in a cryoprotectant buffer.