Dear all, I am trying to phase a large novel structure of 150 kDa with P21 space group. So far I have collected 3.0A datasets from iodinated derivatives in Cu-K alpha. In SAD phasing I got 0.745 figure of merit (FOM) and LLG about 476208.27 (sites in inverse hand gave the same FOM and LLG),by Phenix Phaser-EP. But i am seeing monstrous peak from the substructure solution, it seems that all phases merge into huge fourier peak (like Urenium-atom solution and Fourier truncation ripples; Ref.Bernerd and Rupp) .But it is clear that the iodine has incorporated into the proteins lysine residues where the large electron density has been seen (from partial molecular replacement solution). Would anyone be able to advise me on how it'd be best to improve my phases/density given the limitations of the data? it will be very helpful for me as a learner.
Avisek
