Gel filtration chromatography separates proteins based on

Gel filtration chromatography separates proteins based on their Stokes radius, the radius of the sphere they occupy as they tumble in solution. The Stokes radius is a function of molecular mass and shape. When rapidly tumbling, an elongated protein occupies a larger effective volume than a spherical protein of the same mass. Size-exclusion chromatography employs porous beads. The pores are analogous to indentations in a riverbank. As objects move downstream, those that enter an indentation are retarded until they drift back into the main current. Similarly, proteins with Stokes radii too large to enter the pores (excluded proteins), remain in the flowing mobile phase, and emerge before proteins that can enter the pores (included proteins). Proteins thus emerge from a gel filtration column in descending order of their Stokes radii. Ref: Harper’s illustrated biochemistry. 30th edition page no: 27