Affinity systems based on specific molecular recognition are valuable tools for detection, purification and immobilization of recombinant proteins. Here, novel multipartite affinity fusion vectors were assembled and investigated to allow flexible binding and elution conditions. The rationale for the assembly of different combinations of affinity domains was to take advantage of the wide variety of molecular interactions of these domains for purification, solubilization, detection and immobilization. In total, seven different affinity tags representing five different types of taeligand interactions were studied: (i) monoclonal antibodies-peptides (T7tag and FLAG peptide); (ii) streptavidin-peptide (Strep-tag); (iii) hexahistidyl-metal ions (His,-tag; (iv) bacterial receptors-serum proteins (staphyloccd protein A-Fc and streptococcal protein G-serum albumin); (v) streptavidin-biotin (in vivo biotinylated peptide). Selected tags were evaluated for the production and purification of Escherichia coli DNA polymerase I (Klenow fragment). On the basis of the results, a vector (pAfEtc) was assembled using a novel combination of atlinity domains: (1) an in vivo biotinylated peptide; (ii) a His, sequence, and (ui) a highly soluble serum albumin binding region. Using these three mnities, a wide variety of conditions can be employed for both the binding and the elution steps.