[phenixbb] Autosol: MIRAS

Shya Biswas shyabiswas at gmail.com
Wed Sep 5 18:58:16 PDT 2012


Hi AK,
Did you do a wavelength scan when you collected the SE dataset you
need to put the values of f' and f'' from your wavelength scan in
order to locate the heavy atom sites, 6 methionine should be enough to
phase your molecule.
Shya

On Wed, Sep 5, 2012 at 9:25 PM,  <ash.k at aol.com> wrote:
> Hi all,
>
> I am trying to solve a structure through experimental phasing using AUTOSOL.
> I have a couple of heavy atom derivative datasets (Hg, La, Eu, Cd) and also
> a SeMet data. Unfortunately all the datasets are of low resolution
> (3.7-4.2A) and there are possibly 4-8 molecules in the asu. MIR, SAD and MAD
> alone did not give any convincing solution.
>
> However, MIRAS, with a combination of few heavy atom datasets and the
> anomalous data from SeMet crystals, gave a somewhat satisfactory map. But
> the heavy atom site picked by AUTOSOL list only one of the heavy atoms i.e.
> Lanthanum. In another set of run, the solution of which was not convincing,
> the heavy atom substructure had only Hg. There are 6 Met out of 200 residues
> in one molecule and mass spec results show that Se incorporation is 100%.
>
> Now, my doubt is that why does the heavy atom substructure contain only La
> and how can I get the substructure involving Se from this solution (or the
> datasets used)?  Se location is going to help me a lot for finding a
> starting point to assign side chains.
>
> Any suggestion would be greatly appreciated.
>
> Thanks
> AK
>
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