Purification of recombinant proteins by fusion with thermally-responsive polypeptides

Elastin-like polypeptides (ELPs) undergo a reversible, inverse phase transition. Below their transition temperature (T-t), ELPs are soluble in water, but when the temperature is raised above ft, phase transition occurs, leading to aggregation of the polypeptide. We demonstrate a method for purification of soluble fusion proteins incorporating an ELF tag. Advantages of this method, termed "inverse transition cycling," include technical simplicity, low cost, ease of scale-up, and capacity for multiplexing. More broadly, the ability to environmentally modulate the physicochemical properties of recombinant proteins by fusion with ELPs will allow diverse applications in bioseparation, immunoassays, biocatalysis, and drug delivery.