An easier explanation of the regions in omit map
Hi Nat,
So I have quite a few regions build by the SA_omit map of phenix. But How do
I go about looking at these maps. What am I looking for here. Should I look
at the regions where the occupancy was set zero in all these outputs and
find if I could build some thing from one of the maps? I guess I am asking,
How do I use this information to move forward in refinement? There are 24
regions map and .pdb output in the /OMIT directory.
Thanks,
Ivan
On Fri, May 14, 2010 at 5:52 PM, Nathaniel Echols
On Fri, May 14, 2010 at 5:40 PM, xaravich ivan
wrote: Again this is pretty novice and I would apologize in advance. I ran Simulated annealing omit map in PHENIX and it gave me a bunch of files. I started with a partially built model ( I would say most of it was built) and it gave me an edited pdb that I can open in coot but I the composite omit mtz file is not opening in coot. In fact I cannot open any mtz file from the phenix output /OMIT directory and cannot see any map. I am pretty clueless.
Some clarification:
1. Which version of Phenix, and which platform? 2. GUI or command-line? 3. If you're really making a composite omit map (as opposed to a simple omit map, e.g. for a ligand), ignore the PDB file output by AutoBuild and stick to the original.
One common problem is that on Mac, if you try to open the MTZ file in Coot (using the "Open MTZ", not auto-open), it will open a window to choose column labels in the file, but it opens *behind* the main window, which you need to move to the side temporarily.
-Nat
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On Mon, May 17, 2010 at 10:53 AM, xaravich ivan
So I have quite a few regions build by the SA_omit map of phenix. But How do I go about looking at these maps. What am I looking for here. Should I look at the regions where the occupancy was set zero in all these outputs and find if I could build some thing from one of the maps? I guess I am asking, How do I use this information to move forward in refinement? There are 24 regions map and .pdb output in the /OMIT directory.
Ignore these - only the final map is useful. If you are generating a composite omit map, you want to make sure that what you've built still matches the density reasonably well. Obvious things to look at: - flexible or missing loops - ligands - anywhere the mFo-DFc map shows large blobs at +/- 3sigma - any outliers flagged by validation (both geometry and real-space correlation) I don't usually find it productive to go through the structure residue-by-residue, but this may depend on the data and model quality. What is your resolution and current R-free? (If you are just omitting part of the structure, then you only need to look at the map around those atoms - the rest won't be much different.) -Nat
participants (2)
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Nathaniel Echols
-
xaravich ivan