A molecular biologist is interested in purify a recombinant protein by His-tagging,but the protein and vector both lack histidine residues.In this case,the molecular biologist could use which of the following technique(s)to acheive purification?
A)Add a 6xHis-tag to the C-terminus of the protein. B)Add a series of histidine residues to the N-terminus of the protein. C)Amplify the histidine-encoding sequence by PCR and add it to the gene of interest. D)All of the choices are correct.