Hi Alexandra,

You will have to run the last steps in data processing over and obtain anomalous data in order to calculate that anomalous difference map. Once you have that data you can also refine the occupancy of your Mo atom, however at 0.97 A the anomalous scattering from Mo is not strong (f" is 1.2 electrons).

All the best,

Tom T

From: [email protected] [[email protected]] on behalf of Alexandra Marques [[email protected]]
Sent: Wednesday, June 17, 2015 7:04 AM
To: [email protected]
Subject: [phenixbb] anomalous difference map calculation

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