Heparin-Binding Affinity Tag: A Novel Affinity Tag for Simple and Efficient Purification of Recombinant Proteins.

Heparin, a polysulfated polyanionic member of the glycosaminoglycan family, is known to specifically bind to a number of functionally important proteins. Based on the available information on structural specificity of heparin-protein interactions, a novel heparin-binding peptide (HB) affinity tag has been designed to achieve simple and cost-effective purification of target recombinant proteins. The HB-fused recombinant target proteins are purified on a heparin-Sepharose column using a stepwise/continuous sodium chloride gradient. A major advantage of the HB tag is that the HB-fused target proteins can be purified under denaturing conditions in the presence of 8 M urea. In addition, polyclonal antibody directed against the HB tag can be used to specifically detect and quantitate the HB-fused recombinant protein(s). Herein, a step-by-step protocol(s) for the purification of different soluble recombinant target proteins is described. In addition, useful tips to troubleshoot potential problems and also suggestions to successfully adopt the HB-tag-based purification to a wide range of target proteins are provided.