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:excl: Nanometric size of proteins - How to predict? (Apr/17/2008 )

Ok as I mentioned in the title already,
I´d like to know how can you predict the nanometric size of the protein?
Do you have a rule of a thumb for this?
I have been told that 100kDa is approx. 3nm
Do you agree?

-Joana-

QUOTE (Joana @ Apr 17 2008, 03:01 AM)
Ok as I mentioned in the title already,
I´d like to know how can you predict the nanometric size of the protein?
Do you have a rule of a thumb for this?
I have been told that 100kDa is approx. 3nm
Do you agree?


I think you mean the STOKES radius of globular proteins; it depends on the equivalent average volume; you may use the approximation of an assumed
partial specific volume of 0.725 ml/g according to:

Siegel, L. M. & Monty, K. J. (1966) Determination of molecular
ratios of proteins in impure systems by use of gel filtration and density gradient centrifugation. Application to crude preparations of sulfite and hydroxylamine reductases, Biochim. Biophys. Acta 112, 3462362.

some examples:
alcohol dehydrogenase (yeast): STOKES radius 4.6 nm, 150 kDa,
apoferritin (horse spleen): 6.1 nm, 443 kDa
thyroglobuline (bovine): 8.5 nm, 669 kDa

-The Bearer-