hi I am doing structure at 2.3A resolution. It is a dimer not NCS. I have probelm in tracing last 10 amino acids in the C-terminus in both chains. Both chains come close each other and winds up. So Iam finding difficulty in tracing the chain. I used phenix for rebuilding with all the amino acid included. But autorebuilding is not rebuilding properly, whatever input is given it rebuilds on that. Actually it should be a helix and only at lower cuff off we can observe density for main chain so I tried phenix rebuild to improve it but it's not working. Is there any option to use phenix. I used rebuilding with option automatic and input coordinates and sequence. plz suggest do improve the phases. -- A.S.Ethayathulla Department of BIophysics All India Institute of Medical Sciences Ansai Nagar New Delhi-110029 India