Hi Tony,

It is not necessary to exclude residues when using the torsion angle NCS restraints, even if they are in different rotamers. The potential used to restrain related torsions automatically shuts off in cases where the related torsions are sufficiently different, such as for different rotameric states.

If you want to firmly exclude them, you can define all your NCS groups such as:

refinement {
  ncs {
    torsion {
      restraint_group {
        selection = chain A and resseq 1:50
        selection = chain B and resseq 1:49
      }
    }
  }
}

or something similar for your specific case. If you do define your groups, you have to make sure you define enough groups to cover your entire model.

Jeff

On Thu, Jun 21, 2012 at 2:54 AM, Antony Oliver <Antony.Oliver@sussex.ac.uk> wrote:

How do I specifically exclude particular amino acids from torsion-angle ncs?
From the GUI, it is not obvious.

In a couple of my chains, one or two amino acids are in definite crystal contacts, and are therefore in a different rotamer/conformation compared to the other ncs-related copies.  

Unfortunately, I can't seem to find the right option / keyword to stop the refinement job moving these side-chains to agree with the rotamers found in the other molecules of the asymmetric unit. 

Many thanks,

Tony.


---
Dr Antony W Oliver

Senior Research Fellow
CR-UK DNA Repair Enzymes Group
Genome Damage and Stability Centre
Science Park Road
University of Sussex
Falmer, Brighton, BN1 9RQ

tel (office): +44 (0)1273 678349
tel (lab): +44 (0)1273 677512


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