Hello everybody, I think I have a pseudo-centering problem.
I have a 1.6 ang. dataset of a mutant protein that is an homodimer in solution. Data processing gives the following SG: Space group: P 31 2 1 Average unit cell: 111.36 111.36 28.56 90.00 90.00 120.00 Average mosaicity: 0.24 Rmerge Overall 0.07 However with this SG the unit Cell is too small and monomer doesn't fit the in the AU. I reprocessed the data in other possible SG (including P6) and finally I got 2 equivalent SG's in which I can get a correct Molecular Replacement solution: Space group: I 1 2 1 Average unit cell: 57.07 111.11 192.90 90.00 90.07 90.00 and Space group: C 1 2 1 Average unit cell: 201.10 111.11 57.07 90.00 106.42 90.00 Both with Average mosaicity: 0.38 and Rmerge Overall 0.06, but the corresponding MR solutions do not refine, with R-factor stuck to 45-47%. From what I understand, in the I121 SG I have the NC two-fold axis of the dimer at 1/2a and this originates the pseudo centering and the small P3 Cell Largest Patterson peak with length larger than 15 Angstrom: Frac. coord. : 0.500 0.000 0.000 Distance to origin : 28.566 Height relative to origin : 53.830 % I'm really not so good with symmetry, so I'll be grateful for any suggestion/help/solution from you out there. Many thanks, Giorgio
