[3dem] GroEL best resolution map. (FSC RESOLUTION ??)

[Sjors Scheres]

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

                            Assistant Professor, 
                          School of Biology,
                          Indian Institute of Science
                            Education and Research Thiruvananthapuram
                            (IISER-TVM),

                            
                              Maruthamala P.O., Vithura,

                            
                            Thiruvananthapuram,  695551, Kerala, India

                            

                            natesh at iisertvm.ac.in

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