[3dem] Protein size for negative staining at rotary shadowing

Fang Zhao fang.zhao at helsinki.fi
Thu Aug 26 22:51:46 PDT 2010

Dear Guenter:

Negative staining and rotatory shadowing are two different methods to render
contrast to your protein under EM, you need either one, not both, but if you
want, you can use both as complement. 
Negative staining has higher resolution than shadowing; shadowing allow you
to distinguish your particles from background easier if it is done properly.

Theoretically, negative staining has a resolution limit 2 nm, which
correspond to 30 KD for a globular protein. But I never get that size
visualized under EM, not even for 60 KD. For the best situation, with 100
KD, you may have some hope, for 200 KD, it is for sure you get something.
Good luck for your experiment.

Best Regards,

Fang Zhao, MD. PhD.
Advanced Microscopy Unit (AMU)
Haartman Institute 
Haartmaninkatu 3
PO Box 21, 00014 University of Helsinki
Tel. +358 9 1912 6261
E-mail: fang.zhao at helsinki.fi
Web: http://www.hi.helsinki.fi/amu

-----Original Message-----
From: 3dem-bounces at ncmir.ucsd.edu [mailto:3dem-bounces at ncmir.ucsd.edu] On
Behalf Of Guenter Resch
Sent: 26. elokuuta 2010 18:23
To: 3dem at ncmir.ucsd.edu
Subject: [3dem] Protein size for negative staining at rotary shadowing

Hello everyone,

I have discussed the question what the minimal molecular weight of a
(assumed globular) protein/domain might be to visualise it reliably by
negative staining or rotary shadowing (Pt or W) with a number of people
already, with very different answers.

I am curious at what molecular weight people on this list here are raising
their hopes to see something ...



Dr. Guenter Resch, IMP-IMBA-GMI Electron Microscopy Facility
Email: guenter.resch at imba.oeaw.ac.at; Web: http://cores.imp.ac.at/em
Phone: +43 (1) 79044-4250; Fax/Voice Mail: +43 (1) 79044-224250
Post: Dr. Bohr-Gasse 3, 1030 Vienna, Austria, European Union
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