Hi all,
I could really use some help with the following situation:
I have electron density maps of my protein in two crystal forms. The
first is the apo form which is in P43212 with a = b = 88.2, c = 159.1.
If I soak a substrate for this protein into these crystals, I get a
second crystal form in P41212 with very similar unit cell dimensions (a
= b = 88.7, c = 158.7). The two forms are virtually identical except
that an apparent conformational change causes reverses the handedness of
the packing.
I'd like to superimpose the maps to in an attempt to find density for a
ligand, but I'm having a hard time trying to get this to work. The
closest I have come is by superimposing the coordinates for the two
forms with lsqkab then using the resulting transformation matrix to skew
one of the maps. When I check out the skewed map in coot, it is not
quite right (off by around 2 angstrom).
Is there another way to do this? I'm guessing some of the tricks used in
multi-crystal averaging would be useful here.
Thanks in advance for your reply,
Andrew Robinson
Macquarie University, Australia
