Hi Monica,
Don't give up on heavy atoms before considering various heavy atoms and strategies like short, high conc soaks, longer soaks, binding analysis by PAGE, different concentrations, heavy atom cluster, etc.
Alternatively look into quick soaks in NaCl, Xe phasing, iodination.
Then remote homology modeling for generation of full search models or partial models of portions/domains of the protein if multi-domain. These methods have become more powerful especially if you try combining remote homology model building with ability to use multiple templates/search models, DEN refinement, Rosetta MR, etc.
Will be happy to help with strategies and details if you want to circle back with target specifics.
Regards,
Debanu
> On Oct 5, 2015, at 9:22 AM, Jrh <[log in to unmask]> wrote:
>
> Dear Monica,
> You could try the HATODAS II heavy atom database detailed here in their paper in J Appl Cryst :-
> http://dx.doi.org/10.1107/S0021889809012370
> Best wishes,
> John
>
> Emeritus Prof John R Helliwell DSc_Physics
> School of Chemistry, University of Manchester, M13 9PL, UK.
>
>
>> On 5 Oct 2015, at 08:38, Monica Mittal <[log in to unmask]> wrote:
>>
>> Dear all,
>>
>> I need a general advice. I don't have a suitable Model (Lets say only with a similarity of 15%) and no other model to solve the structure by MR. Then i think of anomalous experiments, but soaking with heavy metals is not good for the crystals. Since the protein is being expressed in Pichia cells, growth in Seleno-media is cumbersome. There are no ligands or ions that i can use for anomalous scattering of protein crystals. I am trying to express it in bacteria but have some issues. What is the option that i can choose to solve the structure of such a protein ? Your suggestions are highly recommended.
>>
>> Thanks in advance.
>> Monica
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