Pore gradient gel electrophoresis

In pore gradient electrophoresis, the separation is  carried out in a direction in the gel in  which the  gel concentration  increases  and its pore size decreases. Proteins migrating along the gel concentration gradient will encounter an increasing frictional force, due to gel sieving,  which will increasingly impede their progress.  Eventually the proteins  will cease migrating at a position where the gel pore size becomes smaller than their diameter. As different proteins will have different diameters, they will each reach a different position  on the  gel.  By reference to  standards, MWs can be calculated.

References 

Dennison, C. (2002). A guide to protein isolation . School of Molecular mid Cellular Biosciences, University of Natal . Kluwer Academic Publishers new york, Boston, Dordrecht, London, Moscow .

Margolis, J.  and Kenrick, K.  G.  (1967) Polyacrylamide gel electrophoresis across a molecular sieve gradient. Nature (London) 214,  1334-1336.

Slate, G. G. (1968) Pore-limit electrophoresis on a gradient of polyacrylamide gel. Anal. Biochem. 24, 2 15-2 17.