It recognizes both the free and protein-conjugated (either soluble or cell bound) form of hexa-histidine. This MAb is highly specific to hexa-histidine and shows no cross-reaction with other structurally related compounds. It has a very high affinity for hexa-histidine and is excellent for use in various techniques. His-Tag Antibody detects recombinant proteins containing the 6xHis epitope tag. The antibody recognizes the 6xHis-tag fused to either the amino or carboxy terminus of targeted proteins in transfected cells. Epitope tags are useful for the labeling and detection of proteins using immunoblotting, immunoprecipitation, and immunostaining techniques. Because of their small size, they are unlikely to affect the tagged protein s biochemical properties. A variety of plasmids contain DNA that encodes an amino-terminal 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. As is the case with other protein tag systems, this polyhistidine tag can often be cleaved at sites recognized by proteases such as thrombin and enterokinases to isolate the protein of interest.