[phenixbb] Refinement of perfect twined data of P31/P32

miyatake miyatake at riken.jp
Mon Apr 22 07:45:35 PDT 2013

Hello, Phenix users,

Now I'm triying to refine almost perfect twining data
(mixing of P31 and P32). It has a twining operation of (h, k, l) = (-h, -k, l),
detected by the xtriage program.
The data qualigy seems to be good, deflacting to 1.6A resolution with Rmerge ~ 5%.

When I refined the MR structures with phenix.refine, however, the model geometries have been worse as over the 20% residues fall into disallowed Ramachandran region,
and Rfree stacked around 30%. 
I tried many options such as real space refinement, SA, bad rotamer fixation, NCS restrain,,.., but they seem to be not so effective as usual twininig cases..

One molecule consists of 202 residues, and three molecules are inolved in AU.

Of course, I used the twin option (-h, -k, l) during the refinement.
Manual collection of the models could not improve the model anymore.

Would anyone please advise me how should I refine the twinned data?


    Hideyuki, M.

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