Hi All, I am looking for some advices on experimental phasing at low resolution, any advices will be highly appreciated.
I have 3 data sets, with similar but not identical cell parameters, Redundancy of each dataset is larger than 6 for overall and 2.5 for anomalous signal, completeness >95% for overall and >90% for anomalous signal: peak: 72.12, 92.07, 128.05, 90, 95.56, 90, P12(1)1, overall Res: 4.5 A, ano signal 7.13 A (cc>0.15), HA=TaBr, f''=20.99 edge: 72.34, 92.28, 127.47, 90, 95.61, 90, P12(1)1, overall Res: 4.1 A, ano signal 8.31 A (cc>0.15), HA=TaBr , f'=-24.17 high remote: 72.18, 92.43, 128.11, 90, 95.60, 90, P12(1)1, overall Res: 4.2 A, ano signal 12.48 A (cc>0.15), HA=TaBr When I tried phenix autosol, the Hyss search gives out a FOM at around 0.30, which is on the boarder line, however the BayesCC is always between 10-20 (meaning handiness not distinguishable?), the SKEW is some where between 0.01-0.05, when it is 0.05, clear solvent boundary could be seen, but the map is not traceable if it is meaningful at all. As I have no idea of how many TaBr cluster could bind, I have tried everything from 1 to 8, and all I got are similar FOM, SKEW and BAYESCC values, with the FOM at sites=5 or 6 better than the others. I am wondering if anybody have any experience with such kind of data: 1. what is a better software (maybe SHAPR or SHELEX?) to use in such a case? 2. What parameters should I change to make Phenix autosol to work? 3. I also have multiple native datasets and peak datasets (TaBr or Pt) which have quite different cell parameters than these MAD datasets, could these datasets be of any help? 4. What is more, a homolog structure is available, though can not solve the structure through MR, is there anyway to use the homolog structure as a aid for experimental phasing? Thank you very much in advance! Bei
