A variety of plasmids contain DNA that encodes a tag consisting of six histidine (6xHis) residues followed by an extended multiple cloning site. The 6xHis tag on the expressed recombinant proteins allows for efficient coupling to Ni2+ affinity resins and purification by single step chromatography. This antibody can be used to detect the carboxyl-terminal 6×his tag in recombinant protein.