A series of six to nine consecutive histidine residues can bind to immobilized metals such as nickel (Ni).

Question

The purification of a protein containing six histidines at its C-terminus using a nickel-based resin would be achieved by _____ chromatography.
size exclusion.
cation exchange.
anion exchange.
hydrophobicity.
affinity.

Answer 1

Histidine has an imidazole side chain and is positively charged. Therefore, the purification would likely be via cation exchange, seeing as though nickel (Ni) is a cation.