In the large-scale production of a particular human protein in E.coli cells,the cDNA corresponding to the protein was modified so that the expressed protein would have six histidine residues at the C-terminus.The purpose of this modification was to
A)facilitate transfer of the cDNA into the E.coli cells.
B)provide a promoter for the transcription of the cDNA in E.coli.
C)facilitate purification of the expressed protein though binding to an affinity column containing chelated nickel atoms.
D)prevent degradation of the expressed protein by E.coli proteases.

Question

Quizplus · Accepted Answer

Adding six histidine residues at the C-terminus of the expressed protein creates a His-tag, which can bind specifically to chelated nickel atoms on an affinity resin column. This allows for efficient and specific purification of the protein after expression in E. coli cells.

In the Large-Scale Production of a Particular Human Protein in E.coli