One way is to refine the best chain out of four, first and then generate a seperate pdb for that chain only and use molecular replacement to find the rest of the three chains. It does help with improving map to certain extent. Also delete the missing residues one by one and then run refmac to see if get any green density back for them to rebuild them in the right conformation..
On Fri, Mar 17, 2017 at 1:51 PM, Polisetty Satya Dev <pvss...@gmail.com> wrote: > Dear all, > > I solved a structure at 2.0 A resolution with R-work and R-free values > 0.25 and 0.32 respectively and I am stuck at Refmac step where there is no > further reduction in R-factor. > > The above stated values were obtained after several rounds of manual > refinement followed by refmac. There are also areas where electron density > is missing around peptide backbone in one of the monomer in ASU. > > Can anyone please tell me how can I improve the electron density and > R-factor. > > The structure solution was obtained using Phaser MR and here are the data > statistics: > > Average unit cell: 81.95, 100.40, 156.96, 90.00, 90.00, 90.00, > > Space group: P212121, > > Completeness 99.5, > > Multiplicity 6.4, > > Four monomers per ASU. > > Solvent content: 47%. > > > Thank you everyone, > > Satya Dev, > > JNCASR. > > -- Dr. Masooma Rasheed Division of Molecular Biosciences Biochemistry Building Level 5 Imperial College London South Kensington London SW7 2AZ UK
