[3dem] GroEL best resolution map. (FSC RESOLUTION ??)
Sjors Scheres
scheres at mrc-lmb.cam.ac.uk
Sun Sep 2 03:14:51 PDT 2018
Dear Natesh,The limitation of 3x the pixel size of the maximum reachable resolution might be true for software written by Marin, but it is definitely not true for many other programs, including relion. We routinely achieve resolutions very close to Nyquist, which is only 2x the pixel size.
Hth,Sjors
Sent from my phone.
-------- Original message --------From: Marin van Heel <marin.vanheel at googlemail.com> Date: 01/09/2018 19:43 (GMT+01:00) To: Natesh Ramanathan <natesh at iisertvm.ac.in>, 3dem at ncmir.ucsd.edu Subject: Re: [3dem] GroEL best resolution map. (FSC RESOLUTION ??)
Dear Natesh,
I just checked the technical data of the EMD-3407 dataset and I
saw that its pixel size is 1.05A . That means that no resolution
levels better than 3 x 1.05A = 3.15A may be claimed for
processing results based on that data set, following the standards
we set in the past (for the younger generation: I am the main
inventor of the FSC ;) ). Going beyond a resolution claim of 3.15A
would mean that the dataset is undersampled, and would thus
require a new data collection with a smaller pixel size. For a
possible resolution claim of, say, 2A you need a maximum pixel
size of 0.66A ! Moreover, the 0.143 threshold FSC threshold used
in this EMD-3407 case is itself wrong, while based on sloppy
statistics.
(https://www.biorxiv.org/content/early/2017/11/24/224402).Bottom
line: to compare the results of different cryo-EM experiments you
need correct resolution criteria applied to sufficiently fine
sampled cryo-EM data.
Cheers
Marin
On 01/09/2018 12:57, Natesh Ramanathan wrote:
Dear All,
Does anyone know/have a GroEL cryoEM map with
resolution 2.5 Å
or better?
I see that the best resolution in EMDataBank is 3.26
Å - EMD-3407 and EMD-3415.
If you have one, is it possible to share the map
with me?
Many thanks.
Best regards,
Natesh
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Dr. Ramanathan Natesh
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