X-ray grade crystals of diphtheria toxin.

Diphtheria toxin, complexed with the endogenous dinucleotide ApUp, has been crystallized under novel conditions involving high concentrations of both polyethylene glycol and salt. Among four crystal forms obtained, one was found suitable for high resolution structural analysis by x-ray diffraction. This form is triclinic (space group P1) with 2 molecules per unit cell; unit cell parameters are a = 70.8 A, b = 70.7 A, c = 65.3 A, alpha = 95.2 degrees, beta = 91.3 degrees, gamma = 99.7 degrees.