# DBT JRF 2022 — Question 24

Exam: DBT JRF 2022 · Section: B · Topic: Biochemistry › Protein Purification Techniques · Difficulty: Medium

## Question

A laboratory is trying to purify a Histone-binding protein from its native source. Which one of the following purification techniques should be used for one-step purification of the protein?

## Options

- **A.** Cation exchange chromatography
- **B.** Immuno affinity chromatography
- **C.** Gel exclusion chromatography
- **D.** Metal affinity chromatography

## Answer

Option B

## Explanation

One-step purification of a histone-binding protein: For one-step purification of a protein that binds histones: • Immuno-affinity chromatography: Use a column with immobilised anti-histone antibodies (or immobilised histones). The histone-binding protein will bind specifically and elute under mild elution conditions (e.g., high salt, pH change). This is highly specific and achieves one-step purification. Why other methods are not ideal for one-step purification: • Cation exchange chromatography: separates by charge; not specific for histone-binding proteins. • Gel exclusion (SEC): separates by size; not specific. • Metal affinity (IMAC): works for His-tagged recombinant proteins, not native histone-binding proteins. Answer: Immuno-affinity chromatography (Option 2).

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