If proteins are separated according to their electrophoretic mobility then type of electrophoresis is

(a) SDS PAGE
(b) Free flow electrophoresis
(c) Electro focusing
(d) Affinity electrophoresis

✅ Correct answer: (B) Free flow electrophoresis

Explanation:

Electrophoretic mobility is the rate at which a molecule moves in an electric field, which depends on factors like charge, size, and shape. Free-flow electrophoresis (FFE) is a specialized technique that separates proteins based on their electrophoretic mobility in a continuous buffer system.

Why is “Free-Flow Electrophoresis” the correct choice?

• Free-Flow Electrophoresis (FFE) separates proteins based on their electrophoretic mobility in a free-flowing liquid medium rather than a gel.
• It is useful for separating charged molecules in a continuous manner without the constraint of a gel matrix.
• Electrophoretic mobility depends on the charge-to-mass ratio of the protein in a given buffer system.

Why Not the Other Options?

• (A) SDS-PAGE ❌

  • SDS-PAGE separates proteins based on size, not electrophoretic mobility.
  • SDS coats proteins with a uniform negative charge, meaning mobility depends only on molecular weight, not inherent charge.

• (C) Electro-focusing (IEF) ❌

  • Isoelectric focusing (IEF) separates proteins based on their isoelectric point (pI), not their general electrophoretic mobility.

• (D) Affinity electrophoresis ❌

  • Affinity electrophoresis separates proteins based on specific interactions with ligands (e.g., antigen-antibody binding) rather than electrophoretic mobility.

Final Answer:

✅ (B) Free flow electrophoresis