Cholera Toxin Crystals Suitable for X-ray Diffraction

Abstract

Large crystals of the cholera toxin were grown; their dimensions, symmetry (P2₁), order, and resistance to radiation make them ideally suited for a high-resolution x-ray structure determination. There is one molecule (approximately 84,000 daltons) per asymmetric unit, and therefore the lattice reveals no molecular symmetry. Two distinct bioassays indicate that the protein from dissolved crystals retains full biological activity.