Crystallization and preliminary X-ray analysis of an anti-insect toxin BmK 16 from Buthus martensii Karsch scorpion

An excitatory anti-insect toxin from BmK scorpion, named BmK 16, has been purified and crystallized recently. Two crystal forms have been obtained by using ammonium sulfate as precipitant at different pH, one of which is single crystal. Diffraction data have been collected for the single crystal on a Mar Research 345 Image Plate. The analyses of the data show that the crystal can diffract to 0.28 nm resolution and belongs to the space group C2 with unit cell parameters a = 4.65 nm, b = 8.52 nm, c= 3.26 nm, α= γ= 90oooooooo, β= 110.5°. There are 2 molecules per asymmetric unit according to its unit cell volume and molecular weight.