On Wed, Oct 20, 2010 at 11:58 AM, Joel Weadge
I have just finished doing molecular replacement and an initial round of refinement (with simulated annealing) on a number of different datasets. They have all be straightforward since most of them are either point mutants and/or co-crystal structures. However, two of the structures are giving me some trouble. The data appears to be of good quality and resolution (2.25 and 2.55Å). The MR proceeds as normal with good scores and then in the subsequent round of refinement the maps (2Fo-Fc and Fo-Fc) look strange. The density is stretched or flattened in one direction. Can anyone help me with what I may be overlooking?
Since our list server rejected Joel's Coot screen capture, I've posted it here: http://cci.lbl.gov/~nat/img/stretched.png My semi-informed guess would be either severe anisotropy or systematic incompleteness (i.e. didn't collect enough degrees). -Nat