Thank you very much for your replies.


Here is what I did:

1)I rerun xdsconv again with Friedls law=false in order to get the mtz file with the F(+) and F(-) columns (new.mtz).  

2) I used my pdb file from the last refinement together with the new.mtz file as input for “Calculate maps” in Phenix and selected the option for anomalous map.

Now I obtained the ANOM PHANOM map. I hope this is correct…

In the anomalous map the largest density is in the Mo and Fe atoms. There is no density in the S of SO3 or SO4 groups, so, this will not help me to decide whether there are SO3 groups in the structure (because for the SO4 I have no doubt).

However, while searching the mailling list I foud this post http://www.phenix-online.org/pipermail/phenixbb/2009-September/013799.html which 
worried me. Should I have used from the beginning this “new” mtz file with F+/F- in order to obtain anomalous differences map at each
refinement step? Do you think that I should go back, transfer the R-free flags to my new mtz file and repeat all the refinements?

Best regards,
Alexandra

 


2015-06-17 16:59 GMT+01:00 Pavel Afonine <pafonine@lbl.gov>:
Hi Alexandra,

to get anomalous difference map you do not need to do anything special: phenix.refine calculates this map by default as long as your input data are Fobs(+) and Fobs(-) or Iobs(+) and Iobs(-).

Refining occupancy of Mo may not be a bad idea given it is likely to be partially occupied.

Pavel


On 6/17/15 06:04, Alexandra Marques wrote:

Hi,


I am in the last refinement steps of a MR model and I want to calculate an anomalous difference map essentially to confirm the presence of a sulfite molecule and to locate vanadium (present in soaking solution). I read that it is necessary to have a mtz file with anomalous data (i.e. F+,F- or I+,I-). However, my data was collected at “normal” wavelenght (0.97) and it was processed with XDS considering Friedls law= true and my mtz file contain the following columns: H K L FP SIGFP. So, can I still calculate a anomalous difference map based on my data?


Since I also have a Mo atom in the active site can I try to refine its occupancy by using the option “anomalous groups” in the refinement strategy?


Thank you very much,

Alexandra


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