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On Wed, 22 Mar 2023 at 03:01, Lijun Liu <[log in to unmask]> wrote:

If data processing to be ok and all possible monoclinic and orthorombic SG gave unreasonable high Rs, maybe good to give a try with p1 space group? Since the p-lattice indexing gave same a and b also very close alpha and beta, it could not exclude the possibility of p1 then twinned (also together with ncs and tNCS) to show higher symmetry?

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On Mar 21, 2023, at 1:25 PM, Jessica Bruhn <[log in to unmask]> wrote:
Hi Gianluca,

Have you checked for diffraction anisotropy problems? It might be worth running it through the STARANISO webserver: https://staraniso.globalphasing.org/cgi-bin/staraniso.cgi. Anisotropy can make your data look twinned and elliptical truncation can help improve maps.

Good luck!

Best,

Jessica
On Tue, Mar 21, 2023 at 11:17 AM Jon Cooper <[log in to unmask]> wrote:
Hello, can you give us a screenshot of a diffraction image, with the caveat that they never look all that good with fine-slicing, still it might help ;-0 Also, an idea of the R-merge, R-meas, CC-half in some of those space groups.

Best wishes, Jon Cooper. [log in to unmask]

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-------- Original Message --------
On 21 Mar 2023, 16:43, Gianluca Cioci < [log in to unmask]> wrote:
Dear All,

I have collected a dataset from a small protein diffracting at 2.7A resolution, here is the space-group determination from XDS:

* 44        aP          0.0      66.3   66.3   83.9 90.2 90.1 98.7
* 31        aP          1.2      66.3   66.3   83.9 89.8 90.1 81.3
* 14        mC         1.3      86.4 100.6   83.9 90.0 90.2 90.0
* 34        mP         2.9      66.3   83.9   66.3 90.2 98.7 90.1
* 13        oC          3.7      86.4 100.6   83.9 90.0 90.2 90.0
* 10        mC         4.9     100.6   86.4   83.9 89.8 90.0 90.0

Clearly, something weird is going on...

The structure can be solved in C2/P21/C2221 with different number of molecules in the AU, with Phaser complaining about strong tNCS modulation.

However the maps look bad and the structure is impossible to refine (Rfact > 0.5) in all the space-groups that I have tried so far...

Thanks in advance for any advice on how to rescue these data !

Cheers,

GIA
--
Dr. Gianluca CIOCI
Toulouse Biotechnology Institute (TBI)
http://www.toulouse-biotechnology-institute.fr/en/research/enzyme-molecular-engineering-and-catalysis/cimes.html
PICT - Plateforme Intégrée de Criblage de Toulouse
http://www.pict.ipbs.fr/

Tel: +33 (0)5 61 55 97 68
E-mail: [log in to unmask]

TBI - INSA Toulouse
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