On Monday, September 17, 2012 11:31:53 am Yuri Pompeu wrote: > Dear community, > > The protein model I am refining has 400 amino acids (3320 atoms). > Some real quick calculations tell me that to properly refine it > anisotropically, I would need 119,520 observations. Given my unit-cell > dimension and space-group it is equivalent to about a 1.24 A complete data > set. > However, I have had a couple of cases where anisotropic B-factor refinement > significantly improved R-work and R-free, while maintaining a reasonable gap > for lower resolution models (1.4-1.5 A, around 70,000 reflections). What is > the proper way of modelling the B-factors?
I laid out my thoughts on this topic at last year's CCP4 Study Weekend. The print version of it may be found here: "To B or not to B: a question of resolution?" Acta Cryst. D68, 468-477. http://dx.doi.org/10.1107/S0907444911028320 One lesson is that lower R-work and R-free does not necessarily indicate that anisotropic refinement is justified. In other words, it is not so easy to determine how much improvement is "significant improvement". > Any thoughts and/or opinions from the community are welcome. > Cheers, > -- Ethan A Merritt Biomolecular Structure Center, K-428 Health Sciences Bldg University of Washington, Seattle 98195-7742
