title: X-ray grade crystals of the enzymatic fragment of diphtheria toxin.
abstract: The enzymatic fragment of diphtheria toxin, fragment A (Mr = 21,167), complexed to the dinucleotide adenosine 3',5'-uridine (ApU), has been crystallized at two different values of pH by hanging drop vapor diffusion. Crystals grown at a pH value of 5.0 (from I) belong to the orthorhombic space group P2(1)2(1)2(1), with unit cell parameters a = 71.2 A, b = 73.0 A, c = 139.8 A and four protomers in the asymmetric unit. Crystals grown at a pH value of 8.1 (form II) belong to the monoclinic space group C2, with unit cell parameters a = 65.2 A, b = 85.6 A, c = 34.6 A, beta = 103.0 degrees and one protomer in the asymmetric unit. Both crystal forms diffract to 2.5 A resolution. The molecular structures of fragment A obtained from these two crystal forms may illuminate the pH-dependent transition of diphtheria toxin during membrane translocation.
authors.affiliation: Molecular Biology Institute, University of California, Los Angeles 90024.
authors.forename: K
authors.initials: K
authors.lastname: Kantardjieff
authors.forename: R J
authors.initials: RJ
authors.lastname: Collier
authors.forename: D
authors.initials: D
authors.lastname: Eisenberg
mesh_terms: D003460:Crystallization; D003461:Crystallography; D004167:Diphtheria Toxin; D006863:Hydrogen-Ion Concentration; D010446:Peptide Fragments
chemical_list: D004167:Diphtheria Toxin; D010446:Peptide Fragments; C029795:diphtheria toxin fragment A