Dear James, I had a similar case with an active site loop which could have an open and closed conformation. This loop had extremely high B-factors but good, albeit low electron density. I believe this was because the loop had this (well-defined) conformation only in say 50% of the protein molecules, having another or disordered conformation in the rest of the molecules. The high B-factors are thus a refinement artifact of this conformation having partial occupancy. In the end, it comes down to (SA-omit) maps.
Best regards, Herman -----Original Message----- From: CCP4 bulletin board [mailto:[email protected]] On Behalf Of James Stroud Sent: Wednesday, May 06, 2009 10:45 AM To: [email protected] Subject: [ccp4bb] Bfactor as Measure of Presence Hello, I have a 2.45 A structure with an average b factor of 50.6. A region I am particularly interested in has an average b factor of 87. At what point do I say that the region is "disordered"? Does it come down to maps? If I have reasonable simulated omit maps but the b factor is 87, how much confidence can I have about my interpretation of the maps? James
