Proteins which run high on SDS-PAGE

[RHODES at UCONNVM.UCONN.EDU]

On Wed, 8 May 1996 13:15:56 GMT Sam Simons said:
>Prolines introduce natural "kinks" in the protein which aren't
>straightened out by denaturing. Since denaturing in SDS creates linear
>polypeptides, this bending will give a larger stokes radius to the
>protein which will cause it to run slower through SDS-PAGE.
-------8<------(snip)
Would you like to elaborate on that?  It seems contrary to what I recall
about f for long rods as opposed to ellipsoids or spheres.  Isn't the
rod an 'extreme' case, such that any alteration of the shape would
decrease f?  As I suggested to the original poster, the possibility of
charge anomaly (i.e. extra +'s) is far more likely, and would not require
something completely out of line with the size range we're dealing with
in this case.  Nevertheless, If someone can show that
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|          moves more slowly than  ___________________, I'd like to see it.
|          I'd be _really_ surprised (not the first time) to see that
|________          _   _
            ______| |_| |____   would run more slowly.
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