The diffraction from the TEM experiments seems to inidicate that the
unit cell is not the same as in the crystal structure and that there
is only one screw axis. Because of this, I'd like to essentially start
from a single protein molecule and build the unit cell based on
symmetry seen in the diffraction pattern. Is there a feasible way to
do this? Thanks,
Jeff
On Nov 28, 2010, at 1:53 AM, Nicholas M Glykos wrote:
Hi Jeff,
I'm currently working on a project where we are attempting to
compare a
single crystal X-ray structure with 2D crystals we've imaged with
TEM. I
have nice 2D cyrstals and low dose cryo images.
My question is whether there is a program in ccp4 that will let you
input a model and then generate a 2D projection using different plane
groups. We are pretty sure, based on electron diffraction, that the
2D
crystals contain a screw axis, as did the X-ray structure. Also,
after
generating the images, is there another program that will calculate
structure factors and a diffraction pattern?
Since you have an X-ray structure, the easiest (?) way would be to
obtain
structure factors for the X-ray structure, select zone axis
reflections
for the sought projection, Fourier transform them, and then use
maprot to
prepare a map with the projection down the sectioning axis. You can
then
directly compare your projections.
Nicholas
--
Dr Nicholas M. Glykos, Department of Molecular Biology
and Genetics, Democritus University of Thrace, University Campus,
Dragana, 68100 Alexandroupolis, Greece, Tel/Fax (office)
+302551030620,
Ext.77620, Tel (lab) +302551030615, http://utopia.duth.gr/~glykos/
