Hi Pooja, Are you positive you have the correct space group and there are no other issues like twinning, etc?
If sure, did you define NCS groups in refinement? TLS refinement? Try different refinement programs? How big is the molecule? Was it solved by MR or experimental phasing? You can try superimposing A/B on C/D and refinement with tight NCS then adjust NCS restraints during model adjustments based on local differences or also see if phenix autobuild helps. Best, Debanu -- Debanu Das Accelero Biostructures > On Jan 24, 2017, at 8:42 PM, Pooja Kesari <pkesar...@gmail.com> wrote: > > Dear All, > > I have a 2.6 A resolution structure having four chains in an asymmetric unit. > The chain A and B have density for almost all residues however we don't have > proper residue density in chain C and D.What can be tried to build chain C > and D ? > > > > Many Thanks > Pooja
