[sharp-discuss] Is there a parameter that estimates/refines the error in the input experimental phases?

Francis E Reyes Francis.Reyes at Colorado.EDU
Wed Apr 20 17:46:23 CEST 2011


Hi Sharpers,

The current phasing problem consists of a molecular replacement  
solution that is sufficient to locate the position of the anomalous  
scatterers using the anomalous signal alone (mostly anomalous  
difference fourier, not so much in the anom LLG when using the MR  
model as input phases). The issue is that the MR solution is 50%  
incomplete (the fold is very well preserved which I imagine is  
providing most of the phasing power). From the PDB I calculate the  
phases to create PHI/FOM/HLA/HLB/HLC/HLD . Of course these calculated  
phases are heavily biased towards the MR solution. I input these  
phases into SHARP as input experimental phases.  Is there a parameter  
which will refine for the error in the experimental phases (especially  
when it comes from a highly incomplete MR solution) ?

Other options: I could mess with the atomic b-factors / scaling prior  
to conversion of the model to HL's? But still, I wonder if SHARP could  
scale down the MR-biased experimental phases during the ML refinement.



F
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Francis E. Reyes M.Sc.
215 UCB
University of Colorado at Boulder







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