title: Crystallization of tuna ferricytochrome c at low ionic strength.
abstract: Previous crystallographic studies of tuna ferricytochrome c have employed crystals grown from solutions of ammonium sulfate, corresponding to an ionic strength of 9.5 M (Takano, T., and Dickerson, R. E. (1981) J. Mol. Biol. 153, 95-115). To obtain a structure at a lower ionic strength, the ferric tuna protein was crystallized at neutral pH with polyethylene glycol at an ionic strength of 45 mM, These crystals (space group P2(1), a = 37.11 A, b = 107.66 A, c = 55.75 A, beta = 105.3 degrees) contain four molecules/asymmetric unit and grow to dimensions of 0.2 X 0.4 X 1.0 mm in 2-4 weeks. They diffract to beyond 1.8 A and are stable in the x-ray beam. We have recorded 28,198 unique Bragg reflections (83% of those possible) to a resolution of 1.89 A from a native crystal. We are undertaking a solution of this structure by the molecular replacement method.
authors.affiliation: Department of Biochemistry, Northwestern University, Evanston, Illinois 60208.
authors.forename: M H
authors.initials: MH
authors.lastname: Walter
authors.forename: E M
authors.initials: EM
authors.lastname: Westbrook
authors.forename: S
authors.initials: S
authors.lastname: Tykodi
authors.forename: A M
authors.initials: AM
authors.lastname: Uhm
authors.forename: E
authors.initials: E
authors.lastname: Margoliash
mesh_terms: D000818:Animals; D003460:Crystallization; D003574:Cytochrome c Group; D005399:Fishes / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D009994:Osmolar Concentration; D011092:Polyethylene Glycols; D014413:Tuna / Q000378:metabolism*; D014961:X-Ray Diffraction
chemical_list: D003574:Cytochrome c Group; D011092:Polyethylene Glycols