Hi Bingfa, first suggestion would be to process your data with the anomalous flag turned on - just in case you happen to have some metal bound coincidentally and you happen to have collected at a decent wavelength to pickup some anomalous scattering. ~30% of proteins in the PDB have a metal bound just FYI and not all of them were soaked in on purpose.
In case you should be that lucky, then you should be able to use the HA phases + your MR model to help building. Jürgen ...................... Jürgen Bosch Johns Hopkins University Bloomberg School of Public Health Department of Biochemistry & Molecular Biology Johns Hopkins Malaria Research Institute 615 North Wolfe Street, W8708 Baltimore, MD 21205 Office: +1-410-614-4742<tel:%2B1-410-614-4742> Lab: +1-410-614-4894<tel:%2B1-410-614-4894> Fax: +1-410-955-2926<tel:%2B1-410-955-2926> http://lupo.jhsph.edu On Feb 13, 2014, at 4:53 PM, Sun Bingfa <sunbin...@gmail.com<mailto:sunbin...@gmail.com>> wrote: Dear Crystallographers, I'm working on a ~90KDa membrane protein, with big extracellular part, probably function as dimer. Now we have dataset to ~4.2 Angstrom and using extracellular homolog structure we can find a solution for this part(~45% of the whole molecule MW) through molecular replacement, and the molecules are packed as layers, and the other part are presumably between these layers. However, we are having trouble to fit the rest of the protein even though there're some density between the solved part. Rfree is at 40% now. We're trying to do heavy atom soaking, such as TaBr. We collected data for MIR but it's not helping so far. (Can I combine these MIR data with the native dataset because the MIR set is only at ~6.5 Angstrom)? Other information: this protein is expressed in Sf9 cells (so very hard to do Se-Met derivatives). The crystals is nice and big and cubic. Any suggestions or examples? Thanks a lot. Bingfa
