Which electrophoresis method is commonly used to separate proteins by size using a gel matrix?

Which electrophoresis method is commonly used to separate proteins by size using a gel matrix?

• A. Zone electrophoresis
• B. Isoelectric focusing
• C. Iontophoresis
• D. Electroendosmosis

Answer: (A)

Gel-based separation relies on a porous network that acts as a sieve. When an electric field drives charged proteins through the gel, smaller proteins weave through the pores more easily and migrate faster than larger ones, producing separation by size. This size-based separation in a gel is the hallmark of zone electrophoresis. In practice, methods like SDS-PAGE apply this principle, coating proteins with SDS to give a uniform charge-to-mass ratio so that size becomes the dominant factor. The other approaches focus on different properties: isoelectric focusing separates proteins by isoelectric point in a pH gradient, iontophoresis involves moving ions into tissues, and electroendosmosis describes bulk solvent flow rather than size-based separation in a gel.

Gel-based separation relies on a porous network that acts as a sieve. When an electric field drives charged proteins through the gel, smaller proteins weave through the pores more easily and migrate faster than larger ones, producing separation by size. This size-based separation in a gel is the hallmark of zone electrophoresis. In practice, methods like SDS-PAGE apply this principle, coating proteins with SDS to give a uniform charge-to-mass ratio so that size becomes the dominant factor. The other approaches focus on different properties: isoelectric focusing separates proteins by isoelectric point in a pH gradient, iontophoresis involves moving ions into tissues, and electroendosmosis describes bulk solvent flow rather than size-based separation in a gel.