Purification of recombinant proteins fused to multiple epitopes

The present invention provides novel identification polypeptides containing multiple copies of an antigenic domain joined in tandem to provide increased sensitivity for the detection and purification of target peptides, a cleavable linking sequence and optionally a spacer domain. Further provided are hybrid polypeptide molecules composed of an identification polypeptide and a target peptide which are produced by recombinant DNA technology and purified using affinity chromatography using one or more ligands. Accordingly, also provided are DNA expression vectors containing DNA encoding for identification polypeptides and methods for using such identification polypeptides for the purification of target peptides. Also provided are methods of constructing DNA vectors encoding the novel identification polypeptides and DNA expression vectors encoding the identification polypeptides linked to a target peptide.