Marek,
Your observation is not unusual. We have seen it for cases with 2
independent molecules in the ASU (Mulichak et al. Proc. Natl. Acad.
Sci. USA 100, 9238-43, 2003.) and a "symmetric" 222 tetramer in the
ASU (Mulichak et al., Biochemistry 41, 15578-89, 2002). Continue
refinement, adding in ligand only where you are see evidence for it,
and then, as Alex said, look for subtle conformational changes or
unique environmental circumstances (e.g., caused by nearest neighbors)
that might explain the result.
Cheers,
Michael
****************************************************************
R. Michael Garavito, Ph.D.
Professor of Biochemistry & Molecular Biology
513 Biochemistry Bldg.
Michigan State University
East Lansing, MI 48824-1319
Office: (517) 355-9724 Lab: (517) 353-9125
FAX: (517) 353-9334 Email: [email protected]
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On Sep 3, 2009, at 8:06 AM, Marek Frischerkase wrote:
Dear all,
I just solved my crystal structure and I was looking for my ligand.
I have 4 molecules in the AU, but I found just in one molecule
density for my ligand. In the other 3 molecules appeared deep red
density when I tried to build something. Is this generally possible?
The binding sites seem to be accessible for all 4 molecules.
Can anyone give some suggestion what happened or what I should do?
Thank you very much,
Marek
