[phenixbb] Stretched Maps

Francois Berenger berenger at riken.jp
Wed Oct 20 19:18:14 PDT 2010

Nathaniel Echols wrote:
> On Wed, Oct 20, 2010 at 11:58 AM, Joel Weadge <joelweadge at hotmail.com> wrote:
>> 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

The picture reminds me the time when I tried to compute a map from a PDB
(I think using FFT from CCP4), but the parameters for the grid were wrong.
The map looked a little like this after (on one axis it looked like it 
was "compressed" by some force).

But, I really know nothing about crystallography so my experience is
probably not relevant.


More information about the phenixbb mailing list