Jacob Keller wrote:
Assuming that your 2d crystals are membrane proteins and are truly 2d
(one layer thick), how can there be a screw axis?
I think you can have 2-fold screw axes in the plane of a single-layer membrane-
in fact I understand P2(1)2(1) is fairly common, with rows of alternately up-
and down- facing molecules along the x and y axes.
JPK
On Sat, Nov 27, 2010 at 12:02 PM, Jeffrey D Brodin<jbro...@ucsd.edu> wrote:
Hi all,
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? Thanks in advance for the help,
Jeff Brodin
My ideas, perhaps naive- keep the plane constant and parallel
to the x-y plane (EM grid?), but rotate the assembly of protein,
using pdbset, to sample different projections.
Construct a 3-D cell around the assembly by choosing an
arbitrary-length c-axis perpendicular to a, b; and calculate
structure factors with ccp4's sfall. select the h,k,0 reflections
and these will be the transform of the projection on the x-y plane,
I think.
eab
