Question

Which purification method is commonly used when recombinant proteins carry a His-tag?

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

Hint:

His-tagged proteins are commonly purified using \[ \boxed{\text{Immobilized Metal Affinity Chromatography (IMAC)}} \] where the tag binds to \[ \boxed{\mathrm{Ni^{2+}} \text{ or } \mathrm{Co^{2+}}.} \]

Answer 1

The Correct Option is C

Step 1: Recall the purpose of a His-tag. A His-tag consists of several histidine residues attached to a recombinant protein to facilitate its purification.

Step 2: Identify the purification method. Histidine residues bind specifically to immobilized metal ions such as \[ \boxed{\mathrm{Ni^{2+}} \text{ or } \mathrm{Co^{2+}}.} \] This property is exploited in \[ \boxed{\text{Affinity chromatography}} \] to selectively purify the recombinant protein. Therefore, \[ \boxed{(C)} \] is the correct answer.