I would take a well-ordered helix out of your
allegedly-correctly-placed model (BEFORE doing any refinement other
than rigid body), phase a 2Fo-Fc and an Fo-Fc map with it, and see if
the helix shows up. If it does, there is some reality in your
solution. If it doesn't, start over from scratch.
Actually, at your resolution a few fat side chains might do as a
reality check rather than an entire secondary structure element. In
fact, you might start by looking at lower-resolution maps, since you
almost certainly haven't phased the high-res terms properly.
Phoebe
At 05:26 PM 2/18/2007, Tim Gruene wrote:
Hi,
I dare say with an R-factor of 0.64, your MR solution is simply wrong.
Just into the blue, you could
1) try various MR-programs (phaser, molrep, amore...)
2) try a different search model
3) try your best model but start with subdomains or chop off possibly
flexible parts
4) have a look at the CaspR server
http://www.igs.cnrs-mrs.fr/Caspr2/index.cgi
5) with crystals that give such good data try to get other pahse
information (soaks, co-crystallisation, SAD (SAD at home), etc.)
Good luck, Tim
--
Tim Gruene
Institut fuer anorganische Chemie
Tammannstr. 4
D-37077 Goettingen
GPG Key ID = A46BEE1A
On Fri, 16 Feb 2007, Emmanuel Prata wrote:
Dear all,
I have a data set of a protein soaked with sacarose, and the statistic
data is good until the molecular replacement (Rmerge 0,07 (24%),
I/Sigma 7 (2,7), completness (99,8 (98%)), and resolution 1,98A. After
this step, I can not get the Rfactor (64%) to drop (I believe the
spacegroup is correct).
Could anyone give me suggestions?
Thank you in advance,
Emmanuel Prata
---------------------------------------------------------------------------------------------------------------------------
Phoebe A. Rice
Assoc. Prof., Dept. of Biochemistry & Molecular Biology
The University of Chicago
phone 773 834 1723
fax 773 702 0439
http://bmb.bsd.uchicago.edu/index.html
http://www.nasa.gov/mission_pages/cassini/multimedia/pia06064.html
