Often, protein to be expressed is fused with histidine and it is called as histidine tags. For their purification, matrix containing ______ is used

Q. Often, protein to be expressed is fused with histidine and it is called as histidine tags. For their purification, matrix containing ______ is used.

A.            calcium ions      

B.            nickel ions          

C.            iron ions

D.            fluorine ions

Answer: nickel ions