Hi,

While doing a precise magnification calibration, as described in the
article in the link below, I get two different values one at 1.049 and the
other at 1.045 for two different datasets. I have to eventually compare the
pdbs from these two datasets. My question is: should I process the final
maps for the two datasets at the above mentioned two different values?

Thanks,

On Sun, Feb 25, 2018 at 10:22 AM, Bruno KLAHOLZ <[email protected]> wrote:

>
>
> Dear Reza,
>
>
>
> you can do this kind of precise magnification calibration by fine-scaling
> the cryo-EM map with respect to your atomic model using for example
> Chimera. Try varying the scales by increments of 0.01 of the pixel size and
> check for the best cross-correlation between the cryo-EM map and a map
> calculated from the atomic model.
>
> Btw, we noticed that the quality of this fine calibration is also visible
> in the geometry quality of the atomic model under refinement (Ramachandran
> outliers etc.), e.g. when using Phenix, Buster etc.
>
>
>
> See for example methods section in https://www.ncbi.nlm.nih.gov/
> pubmed/29143818
>
>
>
> Best regards,
>
>
>
> Bruno
>
>
>
>
>
> *From:* CCP4 bulletin board [mailto:[email protected]] *On Behalf Of *Reza
> Khayat
> *Sent:* 24 February 2018 21:38
> *To:* [email protected]
> *Subject:* [ccp4bb] EM voxel size correction
>
>
>
> Hi,
>
>
>
> Has anyone established a robust method to calibrate the pixel/voxel size
> of a cryo-EM image reconstructions using a known PDB? Thanks.
>
>
>
> Best wishes,
> Reza
>
>
>
> Reza Khayat, PhD
>
> Assistant Professor
>
> City College of New York
>
> Department of Chemistry
>
> New York, NY 10031
>



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