[phenixbb] Refining f'/f"?
Leigh Allen
c.leigh.allen at gmail.com
Thu May 7 11:53:31 PDT 2009
Hello,
I'm new to the world of x-ray crystallography. I just solved my first SAD
structure and I'm on to the refinement stage. The difference map generated
by phenix.refine has really big positive peaks all around my MET residues.
If I switch the atoms to MSE, then I get large negative peaks. Firstly, I'm
not sure if I'm supposed to represent these residues as MET or MSE because
it's a "native," high resolution (1.85) dataset, but it the protein had MSE
residues. When scaling this data, I did not keep F(+) and F(-) separate.
The protein's phases were generated using SAD data to 2.7A, which using
SHARP led to a remarkably interpretable map that allowed me to build in the
protein by hand. My second question is, how should I handle the issue with
large + MET/large - MSE peaks? Do I need to rescale my data to treat it as
anomalous data or is there something I can do within Phenix to fix my
problem. I tried the phenix.refine GUI and set it up to refine f' and f",
but it appears that nothing really changed.
Thanks!
Leigh Allen
*******
Ph.D Candidate
McCafferty Lab
Department of Chemistry
Duke University
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