With 50 mM Zn++ in solution, whatever it is will probably have a Zn salt in
it. So if you wanted to solve it by direct methods or via SAD - that should
do well. Sadly (hur hur) it's probably quite small, whatever it is.

Artem

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On Fri, Feb 3, 2023 at 6:20 AM Mark J. van Raaij <mjvanra...@cnb.csic.es>
wrote:

> like others mentioned, looks like something in between a salt and a
> protein, perhaps TCEP, the ligand, a peptide cleaved from your protein by
> trace protease.
> If possible, I would move the detector closer, collect an atomic
> resolution dataset and try to solve the structure by direct methods. You
> never know, it could be something interesting.
>
> Mark J van Raaij
> Dpto de Estructura de Macromoleculas, lab 20B
> Centro Nacional de Biotecnologia - CSIC
> calle Darwin 3
> E-28049 Madrid, Spain
> tel. +34 91 585 4616 (internal 432092)
> Section Editor Acta Crystallographica F
> https://journals.iucr.org/f/
> https://namedrop.io/markvanraaij
>
> On 3 Feb 2023, at 09:22, kavyashreem <kavyashr...@instem.res.in> wrote:
>
> Dear all,
>
> We crystallized a protein (30kDa) + ligand (by cocrystallization), in the
> condition 10%PEG3350, 50mM Zinc acetate.
>
> Protein was in the buffer 20mM HEPES, 150mM NaCl, 1uM ZnCl2, 4mM TCEP, pH
> 8.
>
> Crystal:                             Crystal:
> crystal under UV m
>
> <b06fc576.png>     <e091c7fd.png>   <8ef9453e.png>
>
> When we collected the data at an in-house facility, it looked something
> like this:
>
> <b903961d.png>
>
> The minimum resolution spot is around 9Ang and maximum ~2.2Ang.
>
> I have not come across a protein diffraction like this, nor of a salt.
> When I ran the gel for the incubated protein (protein+ligand), there was no
> degradation.
>
> Although, I was sure there is some problem with this image I tried
> processing, which could not be, But indexing showed a unit cell  of 11Ang,
> 11Ang, 46Ang in P3. which was quite expected for two of the axes but not
> the third.
>
> Can anyone please shed some light on this diffraction image?
>
> How can it happen?
>
>
> Thank you
>
> Regards
>
> Kavya
>
>
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