Heidi Schubert wrote:
Hi
I would like to convert a map into SFs to use for molecular replacement.
Read on if you think you can help.
I have a 3.7A MAD data set and a few 30% similar homology models for
crystal in i222 space group. The combination of the two pieces of
information generated solvent flattened phases which reflect unique
information and have a FOM of 0.65. Workable, but certainly any model I
build is inherently poor.
I have new data for the same protein (2 mols in the ASU now) in C2 space
group with data to 2.1A. The poor models (original models and an
attempt at a "better" built model from the 3.7A phases) do not work as
molecular replacement solutions in Phaser or MolRep. It would be better
if I could use the i222-3.7A map for the molecular replacement into the
new space group.
PHASER manual says "This density has been cut out and converted to
structure factors in a large cell"
So, how do I do that?
Randy J. Read wrote:
The procedure of cutting out electron density, putting it into a large
unit cell, and backtransforming to get structure factors can be tricky
(as you've discovered), so we put some instructions on our webpage:
http://www-structmed.cimr.cam.ac.uk/phaser/density_as_model.html
The last time I tried that it worked, but let me know if you run into
any problems with your case.
Randy Read
HTH
Ed
