I think any decision depends on the resolution of your two data sets. If they are very different I would choose the higher resolution one.
If that is the Anom data then I would use the anom signal at least in the first cycles to improve the phases.. Eleanor On Thu, 3 Jan 2019 at 14:59, Piotr Wilk <[email protected]> wrote: > Dear CCP4 experts, > > I'd like to ask your opinion about using anomalous signal in refinement of > crystal structures in addition to using high resolution native data. > I am working on a series of structures for which I have collected two data > sets (from the same crystal): > 1 - native with higher resolution > 2 - anomalous at MN absorption edge peak. > The structures were solved with MR and preliminary refinement using the > native data only yields decent statistics, but I also use anomalous data to > verify presence and position of manganese ions. For this I used ANODE which > lists four strong peaks (~30 sigma) as expected for manganese ions and > around 45 weaker peaks (~9-5 sigma) for sulfur atoms in Cys and Met. I am > happy to use this information in model building but I was also wondering if > (and how) beneficial would it be to use both high resolution structure > factors and somehow lower resolution yet highly specific anomalous signal > in the same round of refinement? > In Refmac5 I can use either refinement with "no prior phase information" > taking FP and SIGFP or "SAD data directly" with SIGFP F(+) SIGF(+) F(-) > SIGF(-), but I didn't find any "MAD" option to use both. > I have the following columns in my mtz files: > for native data: H K L FP SIGFP FreeRflag > for anomalous data : H K L FP SIGFP F(+) SIGF(+) F(-) SIGF(-) FreeRflag > or : H K L FP SIGFP DANO SIGDANO ISYM FreeRflag > > I could use CAD to merge the interesting columns into a single mtz file > containing: > H K L FP SIGFP FreeRflag F(+) SIGF(+) F(-) SIGF(-) DANO SIGDANO > > I'd appreciate any comments or advise how to use both sources of > information in the refinement. > > I wish you all a Happy New Year. > Kind regards, > Piotrek > > > > ------------------------------ > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 > ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1
