Dear Nazia, you give very little details, so it is difficult to give a specific advice. Here are some comments: -How high is your Rfree? Depending on the resolution of your data, an Rfree in the 25-30% range while not good, may still be acceptable. -Are there problems like ice-rings in your data? -Did you check the complete protein chain with a graphics program (coot) for residues/loops which may need rebuilding? -Did you try other refinement programs? (Buster, Refmac, Phenix). -Try different weights (in Refmac: weight MATRIX keyword). I recently had a case where only with a very specific weight the R and Rfree would go down. Just run the same refinement job several times with different weights.
Good luck! Herman -----Ursprüngliche Nachricht----- Von: CCP4 bulletin board [mailto:[email protected]] Im Auftrag von Nazia Nasir Phd2009,ProteinCrystall.Lab Gesendet: Dienstag, 10. Dezember 2013 07:52 An: [email protected] Betreff: [ccp4bb] Rfree problem Hi, I am facing a problem in refining one of my structures. With every refinement the Rwork is going down. However, the Rfree is stuck and is not going down with refinement. I have already solved the structure without the co-factor bound. This structure is with the co-factor bound. Can anyone suggest the reason for the Rfree getting stuck? Thanks -- Nazia Nasir PhD Scholar Protein Crystallography Lab National Institute of Immunology New Delhi
