But that wouldn’t incorporate other useful information, such as percentage 
completeness in the outer shell and whether inclusion of the reflections in the 
outer shell for refinement actually effects the resulting structural model and 
map to a significant degree.

Diana

**************************************************
Diana R. Tomchick
Professor
Departments of Biophysics and Biochemistry
UT Southwestern Medical Center
5323 Harry Hines Blvd.
Rm. ND10.214A
Dallas, TX 75390-8816
[email protected]<mailto:[email protected]>
(214) 645-6383 (phone)
(214) 645-6353 (fax)

On Feb 28, 2020, at 10:03 AM, Phoebe A. Rice 
<[email protected]<mailto:[email protected]>> wrote:

EXTERNAL MAIL

Can we get some momentum for the "standard table 1" including TWO numbers - 
outer limit used in refinement, and nominal resolution based on some standard 
such as I/sigI =2 (or 3, or whatever the community can agree on)?  That would 
hopefully cut down on all the reviewer complaints of overstated resolution.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Phoebe A. Rice
Dept. of Biochem & Mol. Biol. and
 Committee on Microbiology
https://voices.uchicago.edu/phoebericelab/


On 2/28/20, 6:56 AM, "CCP4 bulletin board on behalf of Malý Martin" 
<[email protected]<mailto:[email protected]> on behalf of 
[email protected]<mailto:[email protected]>> wrote:

   Dear colleagues,

   I agree with all the previous responses, it is a pity to throw away
   useful high-resolution data. The problem of high-resolution cutoff
   estimation is also nicely summarized in another paper by Andrew Karplus
   and Kay Diederichs "Assessing and maximizing data quality in
   macromolecular crystallography"
   https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4684713/ . It is suggested
   using CC1/2 for the selection of the cutoff for data processing (not
   I/sigI or R_whatever). Later on, the decision should be validated
   performing the paired refinement protocol.

   Good luck with the argumentation.
   Martin


   On 2/28/20 11:08 AM, LMB wrote:
Ask the referee - (apart from the other suggestions here)

‘How would removing data Improve my model?”

Sent from my iPad

On 28 Feb 2020, at 08:22, dusan turk 
<[email protected]<mailto:[email protected]>> wrote:

Hi,

Browsing through the recent discussion on EM data resolution cutoff
it occurred to me that the X-ray diffraction community isn’t that
unanimous either.

My stand:

When the default resolution cutoff provided with the data processing
software in electron density map calculation and refinement delivers
quality maps noisier than expected and/or too high R-factors I start
adjusting the resolution cutoff by lowering the resolution and trying
alternative space group. Hence, I allow the data processing programs
to suggest where to draw the line (be it CC1/2, I/sigI, R merge, R
sym, R p.i.m. and R r.i.m, …) , unless there are problems.

Doing so, I came into a dispute with a referee who shaped his request:

"It is well accepted that the criteria for resolution cutoff should
consider both I/SigI and Rmerge for the outer most shell. For data
sets collected at synchrotron sources, the criteria of I/SigI > 5 and
Rmerge <50% can be taken as a good practical reference.”

So where do we stand? Which are the most objective criteria for
resolution cutoff to be used in diffraction data processing? Which
number of shells to use when calculating the statistics? Do we have a
consensus?

best wishes,

dusan turk



Dr. Dusan Turk, Prof.
Head of Structural Biology Group http://stef.ijs.si/
Head of Centre for Protein and Structure Production
Centre of excellence for Integrated Approaches in Chemistry and
Biology of Proteins, Scientific Director
http://www.cipkebip.org/
e-mail: [email protected]
phone: +386 1 477 3857 Dept. of Biochem.& Mol.& Struct. Biology
fax: +386 1 477 3984 Jozef Stefan Institute
Jamova 39, 1 000 Ljubljana,Slovenia
Skype: dusan.turk (voice over internet: www.skype.com

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