[ccp4bb]: Sulphur sub-structure solution

[Iain Kerr <idk@st-andrews.ac.uk>]

***  For details on how to be removed from this list visit the  ***
***          CCP4 home page http://www.ccp4.ac.uk         ***

Hi all,

I'm in the process of integrating/scaling (Mosflm and SCALA) a dataset
collected @ the ESRF in the hope of solving the sulphur sub-structure of a
12kDa protein. We assume 2mols/asu.

I've read some interesting papers but am wondering what to look for in
terms of the size of anomalous signal and comparison of Ranom  with say
Rfac or Rcum. What should I be looking for in the scaling ?. We also have a
problem with Merohedral twinning (say 2-5% in this data) in P61/P65 and I'm
wondering if it is worth detwinning the data for phase determination or if
this is negligible. I would hope to use Direct Methods in structure
solution prob SnB and I know detwinning data can lead to  loss of the
anomalous signal in the background although I know of at least one MAD
structure that has been solved with a high degree of pseudomerohedral
twinning.

Thanks in advance for any help,

Iain

 

***********************
Iain Kerr,
Biomolecular Sciences building,	
3rd Floor,
North Haugh,
St.Andrews,
Fife KY16 9ST,
Scotland. 
***********************