The molecular weight of the Hope Diamond is about 5.5e24 Daltons, and I
bet it diffracts to better than 1.0 A.
For every rule there are exceptions, and for every distribution there
are "outliers". Maybe a more informative number would be obtained after
discarding the best 1-5% and see what is "best" after that? This is
sometimes called "histogram equalization", and it is a very helpful
filter when viewing diffraction images.
The highest resolution x-ray spot from crambin has never been measured.
The last heroic attempt to push the recorded resolution of crambin got
to 0.45 A, but only because of detector geometry limitations. This is
typical of "small molecule" data collection, where ultimately the Ewald
sphere diameter is the only thing that limits resolution.
Another way to look at it is the number of significant Fourier terms in
the map. By that metric I believe rubisco is still the champion of
"information content" in the PDB.
-James Holton
MAD Scientist
On 6/9/2020 6:54 AM, Edward Snell wrote:
I’m reminded of a comment Wim Hol made at an ACA meeting many years
ago during a discussion of resolution. He noted that you had to add
molecular weight into the equation also to really get a handle on how
impressive an experiment is. Some proteins are larger small molecules,
others are tour de force examples.
Having collected and still working on a 0.8A data set from a tetramer
of a ~40kDa protein I advise my students only half-jokingly to move
the detector back and pretend that didn’t see anything beyond 1A. If
you can answer the question with the resolution you have then there is
no need to push the data, risk radiation chemistry impacting the
interpretation, and spending months of computing time to try to
explain every niggly detail that pops up J
Best,
Eddie
Edward Snell Ph.D.
Director of the NSF BioXFEL Science and Technology Center
President and CEO Hauptman-Woodward Medical Research Institute
BioInnovations Chaired Professorship, University at Buffalo, SUNY
700 Ellicott Street, Buffalo, NY 14203-1102
hwi.buffalo.edu <http://hwi.buffalo.edu/>
Phone: (716) 898 8631 Fax: (716) 898 8660
Skype: eddie.snell Email: esn...@hwi.buffalo.edu
<mailto:esn...@hwi.buffalo.edu>
Webpage: https://hwi.buffalo.edu/scientist-directory/snell/
hwilogo
Heisenberg was probably here!
*From:*CCP4 bulletin board <CCP4BB@JISCMAIL.AC.UK> *On Behalf Of
*Tobias Beck
*Sent:* Tuesday, June 9, 2020 9:46 AM
*To:* CCP4BB@JISCMAIL.AC.UK
*Subject:* Re: [ccp4bb] Highest resolution of X-ray / neutron /
electron crystallography, cryo EM
Dear all,
Thanks for the link to the latest BioRxiv papers! So for cryo EM it is
1.2 now. Any numbers for neutron?
Best, Tobias.
Tobias Beck <tobiasb...@gmail.com <mailto:tobiasb...@gmail.com>>
schrieb am Di. 9. Juni 2020 um 15:35:
Dear all,
I was asked by a student what the highest resolution is, for each
of the four methods listed above. Maybe someone has researched the
current numbers previously and would like to share them? For
X-ray, I found 0.48 A in the PDB. For EM method details, the PDB
gives me 0.6 A, but it is actually for electron diffraction. I
found a structure with 1.8 A for Cryo EM.
I am aware that resolution is only one parameter and that high
resolution may not correspond to high data quality. However, maybe
someone knows the record holders, either for biomacromolecules or
small molecules or for both.
Thanks!
Best, Tobias.
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