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Dear Misbha, Before you throw stones at other peoples' work: - have YOU tried to refine a structure at 3.9A, particularly with older software? - there are many structures in the database that are related to lambda repressor. Have you checked how the structure in question compares to those determined at higher resolution? Is the overall fold the same? Is the sequence register the same? Remember that it is unreasonable to expect that all the side chain rotamers will be correct at 3.9A. - When you looked at the actual electron density, what, exactly, did you see that suggested the structure may not be correct? - The structure factors were deposited, so it should be easy for you to try re-refining it yourself with newer software, and see if it makes much difference to the final model. - If you've gone through all those steps, and are still convinced that this structure is problematic, please do let the community know! ++++++++++++++++++++++++++++++++++++++++++ Phoebe A. Rice Dept. of Biochemistry & Molecular Biology The University of Chicago [log in to unmask]<mailto:[log in to unmask]> ________________________________ From: CCP4 bulletin board [[log in to unmask]] on behalf of Misbah ud Din Ahmad [[log in to unmask]] Sent: Thursday, April 23, 2015 11:03 AM To: [log in to unmask] Subject: [ccp4bb] 3BDN, 16.5% Ramachandran Outliers!!!!! Dear crystallographers, The PDB entry http://www.rcsb.org/pdb/explore.do?structureId=3BDN has 16.5% Ramachandran outliers. When I opened this PDB file in coot and checked for Ramachandran outliers, the results are: In preffered region: 58.04% In allowed regions: 19.78% Outliers: 22.17% !!!!!!!!! With an R-free of 37.4% at 3.9 A resolution, could you please tell me how reliable this structure of Lambda repressor bound to DNA is? Thanks Misbha