A new protein fusion expression system was conceptualized and is being developed to provide tag-free recombinant protein purification via one-step chromatography. Phase I of this project includes optimization of the activity of the key component in the fusion construct, streamlining the target cloning method, and applications in bacteria expression system. Because this purification method is simple, low cost, time saving, Phase II of this project will advance the one-step method for eukaryotic expression and apply the method to producing proteins for proteomic studies and biotransformation applications