Hello,

I tried to use AutoSol to solve a SAD date set. The space group is P212121, with two proteins per ASU each containing one SeMet. However, the Hyss would always find 4~5 extra sites per ASU besides the two SeMet residues.

So my questions are:

a. Is this normal to have so many more sites identified? Or what might be the problem?

b. Could I remove those extra Se sites during refinement if the occupancy is low or doesn't make sense biologically?

Here are some details:

1. Most of the extra sites are around 20% occupancy and not within the range as alternate SeMet side-chain positions. One of them even overlapped with the position where should be a ligand phosphate.

2. The 2Fo-Fc map and AutoBuild solution looked fine, but the Fo-Fc map is kinda noisy with positive peaks showing up within the main-chain density which causes troubles for refinement.

3. No twining was detected for the dataset. Several space groups have been tried (including no screw axis) and all of the solutions contained more sites than there should be.