This would also be ideal for refinement of structures built into cryoEM maps, where we often have many different structures which have different global conformations but presumably similar local geometry. I don't know of any way to do this currently though (although I look forward to the implementation in phenix)... if anyone has any ideas for currently available methods to do this I would be interested to hear them!
Cheers,
Oliver.
On Tue, 25 Aug 2015 08:01:22 -0700, Pavel Afonine <[log in to unmask]> wrote:
>Hi Tristan,
>
>yes, this is what we are implementing as next generation joint X-ray and
>neutron refinement in phenix.refine. In a nutshell: you have two crystals
>of the same structure, you collect X-ray data set from one crystal and
>neutron data set from another crystal, then you refine two structures
>against two data sets simultaneously and apply similarity restraints
>between the two structures. Allowable differences between two structures
>include hydrogens and deuteriums, different solvent structure, local
>geometry deviations, etc.
>
>This can be generalized of course for cases you mentioned.
>
>All the best,
>Pavel
>
>On Mon, Aug 24, 2015 at 9:33 PM, Tristan Croll <[log in to unmask]>
>wrote:
>
>> Hi all,
>>
>>
>> It's already common practice with low-resolution crystals to apply
>> torsion-angle restraints on NCS copies and/or to higher-resolution
>> reference structures. But say you have two (or more) crystals of the same
>> protein grown under different conditions, and diffracting to comparable
>> (low) resolution, where no NCS or high-res reference structure is
>> available. In principle, the idea of refining these simultaneously with
>> torsion-angle restraints to each other seems not much different from
>> refinement with NCS - but I'm wondering, has this ever been done?
>>
>>
>> Best regards,
>>
>>
>> Tristan
>>
>
|