Hi,
Phaser's ability to use a statistically-weighted ensemble model for molecular replacement helps it to work pretty well with NMR structures, which typically come with an ensemble of 20 models. Frequently, there are parts of an NMR structure that are poorly determined by the data, so it is very helpful to trim those diverging portions off. This can be done easily with the ensembler tool that is distributed with Phaser in both CCP4 and Phenix, turning on the option "trim=True". Phaser will automatically construct an ensemble model with the PDB file for an NMR structure, in which the different models are flagged by MODEL and ENDMDL records.
The other important question is what error estimate to provide for an NMR model. NMR models are not usually as accurate as X-ray models (though the methods continue to improve), and we've found that a generic estimate that the RMS error is 1.5A works in a variety of cases.
Good luck!
Randy Read
> On 24 Aug 2016, at 19:42, Aditi Deshpande <[log in to unmask]> wrote:
>
> Hello,
> How can I use an NMR model for molecular replacement for solution of a crystal structure?
> Thanks,
> Aditi
>
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Randy J. Read
Department of Haematology, University of Cambridge
Cambridge Institute for Medical Research Tel: + 44 1223 336500
Wellcome Trust/MRC Building Fax: + 44 1223 336827
Hills Road E-mail: [log in to unmask]
Cambridge CB2 0XY, U.K. www-structmed.cimr.cam.ac.uk
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