[3dem] Cryo-EM size limit

[Keiichi Namba]

Dear Roman and Reza,

This may be the smallest one, although not a protein.
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http://www.ncbi.nlm.nih.gov/pubmed/19492821

Nano Lett. 2009 Jul;9(7):2747-50.
High-resolution structural analysis of a DNA nanostructure by cryoEM.

Kato T, Goodman RP, Erben CM, Turberfield AJ, Namba K.
Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan.

Abstract
Many DNA nanostructures have been produced and a wide range of potential applications have been proposed. However, confirmation of accurate 3D construction is particularly challenging. Here, we demonstrate that cryoEM may be exploited to obtain structural information at sufficient resolution to visualize the DNA helix and reveal the absolute stereochemistry of a 7 nm self-assembled DNA tetrahedron. Structural analysis at such high resolution by cryoEM image analysis is unprecedented for any biological molecule of this size.

PMID: 19492821 [PubMed - indexed for MEDLINE]
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Regards,
Keiichi


At 9:26 AM +0100 10.11.3, <R.I.Koning at lumc.nl> wrote:
>Dear Reza,
> 
>Considering the on-going discussion I would additionally like to point out that there is a difference between 2D imaging of protein structures using cryo-EM and getting a succesfull 15 angstrom 3D reconstruction using single particle imaging and reconstruction techniques.
> 
>A successful reconstruction of small particles (lets say <300 kDa) depends  on the shape of the particle and also on when you consider it to be successful and what feature you want to resolve. Therefore it is difficult to get a practical limit.
> 
>I wonder what the smallest particle is that has been resolved using singel particle cryo electron microscopy to 15 angstrom until now. Does anybody know? That might give you a practical answer to your question.
> 
>Regards,
> 
>Roman
> 
>Roman I. Koning, Ph.D.
>Leiden University Medical Center
>Department of Cell Biology
>Section Electron Microscopy
>Postal Zone S1-P
>P.O.Box 9600
>2300 RC, Leiden
>The Netherlands
> 
>visiting adress:
>Einthovenweg 20,
>Building 2, zone S1-P, room R-90-20
> 
>tel (31) 71 526 9296
>fax (+31) 71 526 8270
>r.i.koning at lumc.nl
> 
> 
>
>>
>>-----Original Message-----
>>From: <mailto:3dem-bounces at ncmir.ucsd.edu>3dem-bounces at ncmir.ucsd.edu [mailto:<>3dem-bounces at ncmir.ucsd.edu] On
>>Behalf Of Reza Khayat
>>Sent: Wednesday, October 27, 2010 12:34 PM
>>To: <mailto:3dem at ucsd.edu>3dem at ucsd.edu
>>Subject: [3dem] Cryo-EM size limit
>>
>>Hi,
>>    I was wondering if anyone had an opinion on what the smallest
>>macromolecular sample (in size or mass) could be for successful
>>single particle cryo-EM and image reconstruction?  I'm hoping for a
>>resolution better than 15“M  This would be without the use of phase
>>plate technology.
>>
>>Thanks,
>>Reza
>>