The structure of the hexagonal crystal form of hen egg-white lysozyme

The three-dimensional structure of hen egg-white lysozyme (HEWL) in a hexagonal crystal form has been determined and refined to 1.46 Å resolution. This hexagonal crystal form crystallizes from a saturated sodium nitrate solution at pH 8.4. The crystals belong to space group P6₁22, with unit-cell parameters a = b = 85.64, c = 67.93 Å. A total of 165 water molecules, 16 nitrate ions and five sodium ions were located in the electron-density map. The hexagonal crystal form exhibits a higher solvent content and a higher degree of disorder than other crystal forms of lysozyme. The flexibility of the protein depends on the crystal packing, although some residue ranges are flexible in all native HEWL crystal forms.