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
