[phenixbb] Refining low resolution structure

[Pavel Afonine]

Hi Humberto,

I suggest that you try to use TLS in combination with group isotropic B 
(one B per residue). In my experience this almost always improves the 
model. It is important that you make a thoughtful decision about the TLS 
groups rather than refine the whole molecule as one TLS group (which is 
default).

Pavel.


On 4/29/2008 10:30 AM, Humberto Pereira wrote:
> Dear all
> I was trying to refining a low resolution structure with Phenix.
> The crystal belongs to the SG P6122 with one monomer per ASU. The 
> monomer contains
> approximately 270 residues. There isn't any NCS operators.
> The crystal diffracts up to 4.0 Angstrons, with good statistics, 
> however I have only 4204 unique reflections.
> I solved the structure by MR by Phaser and the solution was quite 
> reasonably.
> Initially I performed a phenix refining cicle with SA + rigid body, 
> however the Rs values is very divergent (43 and 59%),
> so I decided to use the key 
> xray_data.r_free_flags.ignore_r_free_flags=true in order to save my 
> precious reflections with and without
> SA, and I also use the group_adp., in those cases the R is about 39-40%.
> I want a help to decide the best refinement strategies for low 
> resolution refinement with phenix.
> BTW I'm trying to produce some different constructions of the gene, 
> expecting improve the resolution.
>
> Thanks
> Humberto
>
>
>
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