Recombinant DNA technology allows the addition of short pieces of well-defined tags, “peptides” or proteins at the amino or c-terminus of target genes, which can provide 'affinity handles' designed to bind specific matrices. Therefore, tags enables a selective identification and purification of the protein of interest. Poly-His (His x 6) containing proteins can be purified by immobilized metal ion affinity chromatography (IMAC), making use of its high affinity for transition metal ions (1-4). This purification system eliminates the harsh conditions required to elute protein from ligand affinity columns. Numerous recombinant fusion proteins have been engineered with histidine tags to allow detection, isolation and purification of fusion proteins (1-4). Anti-poly may be used to identify the expression of a poly-histidine fusion protein in bacteria, bacterial lysates or cells and tissues transfected with a poly-histidine fusion protein expression vectors.