Dear ccp4 users,
I have been trying to solve the structure of a protein which has 760
residues. The protein has three domains and there is no homologue
structure for the first domain which is about 300 residues. The top hit
from PDB blast gave an identity of 36%. The resolution was 2.97 A. I
have tried different Molecular Replacement programs with different
models, the best solution, which was a partial solution, was from MrBump
and had only the last two domains in the structure. These two domains
fit in the density well and I have manually built that part a few time,
so I am afraid that there is nothing I could do with these two domains
at this stage. The Rfactor and Rfree are about 31% and 37% now. I have
also tried many tracing and autobuild programs from both ccp4 and
phenix, nothing really helped. Things like phase improvement and solvent
flattening have also been tried. I could definitely see some density map
for the first domain but it is difficult to trace the chain from coot at
this resolution. The statistics are all ok with a P21 space group. I did
check other possibilities of the space group. This crystal was from a
screening and I could not reproduce it at this stage.
So does anyone have any experience in solving this kind of problem?
Actually, I also have another similar case at the moment.
Many thanks in advance.
All the best,
Jason
University College London
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