size of ferritin particles

Dr. Jorge Garrido
Tue Aug 8 17:44:34 EST 1995

fjhblazq at (FRANCISCO J HERNANDEZ BLAZQUEZ fzea - zab 0195 616122 - 
283) wrote:
>I'm workin with ferritin from horse spleen (Sigma I) as an
>electron microscopic marker. Although it is easy to identify the
> particles in the micrographs, I would like to know the exact
>size of theses particles. Could you help me, please
>Thank you

The protein shell of ferritin (apoferritin) is roughly 11 nm in diameter, 
but the electron-dense ferric hydroxide micelles are concentrated in a 
central tetrahedron measuring 5.5 nm across. If you are employing one of 
the published techniques seeking to enhance the electron density of 
ferritin (such as Ainsworth and Karnovsky, J. Histochem. Cytochem. 20, 
225 (1972)), your particles probably measure 7-8 nm.
Hope this helps!


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