Question

Name the technique used for separation of proteins according to size?

• A. Affinity chromatography
• B. Reverse phase chromatography
• C. Ion exchange chromatography
• D. Gel filtration

Hint:

In gel filtration, larger molecules elute first (in the void volume, \( V_0 \)), while smaller molecules elute later.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Protein purification uses chromatography to separate proteins based on physical and chemical properties such as charge, hydrophobicity, binding affinity, and molecular size.

Step 2: Detailed Explanation:
Let us review the basis of separation for each listed chromatographic technique:
Affinity Chromatography: Separates proteins based on specific reversible interactions between a protein and a ligand immobilized on a solid support (e.g., antigen-antibody, enzyme-substrate, or receptor-ligand interactions).
Reverse Phase Chromatography: Separates molecules based on hydrophobic interactions between non-polar regions of the protein and hydrophobic ligands on the stationary phase.
Ion Exchange Chromatography: Separates proteins based on their net surface charge at a specific pH, using charged stationary phase resins.
Gel Filtration (Size Exclusion Chromatography): Separates proteins based on their molecular size or hydrodynamic volume.
The stationary phase consists of porous beads.
When a protein mixture passes through the column, larger proteins cannot enter the pores of the beads and bypass them, eluting quickly.
Smaller proteins enter the pores, taking a longer, winding path through the beads, and elute later. This effectively sorts proteins by size.

Step 3: Final Answer:
Gel filtration is the chromatographic technique used to separate proteins according to their size.