title: Phasing protein structures using the group-subgroup relation.
abstract: Diffraction data from two non-isomorphous crystals (forms 1 and 2) of an artificial protein with a four-helix bundle motif, di-Co(II)-DF1-L13A, have been collected using synchrotron radiation. The phase of form 1 has been assigned using the group and minimal non-isomorphic supergroup relation between the space group of the previously determined di-Mn(II)-DF1-L13G structure and the space group of this form. This unconventional method of solving the phase problem has also been tested with form 2 using a reverse relation. The structure of the latter form has been solved using the group and maximal non-isomorphic subgroup relation with the space group of form 2 of the analogous dimanganese protein. This application has shown that this phasing method can be used for solving the protein structures of polymorphic crystals as an alternative to the molecular-replacement method.
authors.affiliation: Centre of Excellence in Biocrystallography, Department of Chemical Sciences, University of Trieste, Via L. Giorgieri 1, 34127 Trieste, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Di Costanzo
authors.forename: Federico
authors.initials: F
authors.lastname: Forneris
authors.forename: Silvano
authors.initials: S
authors.lastname: Geremia
authors.forename: Lucio
authors.initials: L
authors.lastname: Randaccio
mesh_terms: D020816:Amino Acid Motifs; D001665:Binding Sites; D019281:Dimerization; D007091:Image Processing, Computer-Assisted; D008958:Models, Molecular; D011506:Proteins / Q000737:chemistry*; D014961:X-Ray Diffraction / Q000379:methods*
chemical_list: D011506:Proteins