What is the main function of gel filtration chromatography in protein purification?

• A. Separating based on charge
• B. Separating based on size
• C. Separating based on shape
• D. Separating based on binding affinity

Answer: (B)

Gel filtration chromatography, also known as size-exclusion chromatography, primarily separates proteins based on their size. In this technique, a column is packed with porous beads that allow smaller molecules to enter the pores while larger molecules are excluded from them. As a sample mixture is passed through the column, larger proteins travel faster through the column and elute first, while smaller proteins lag behind as they navigate inside the beads.

This method is particularly effective for purifying proteins because it can separate a wide range of molecular sizes without altering the protein's structure or functionality, making it useful for several applications in biochemical research. It is commonly used as a first step in protein purification protocols, allowing scientists to remove smaller contaminants and provide a more concentrated sample of the target protein for further analysis or purification steps.