A non-chromatographic protein purification strategy using Src 3 homology domains as generalized capture domains

• Novel use of SH3 domains and binding ligands for elastin-like polypeptide mediated affinity capture (EMAC).
• Use of two binding ligands of different binding affinity towards SH3 domains to allow bind and elute of various proteins.
• Multiple tandem repeats of ligands and SH3 domains to increase apparent binding affinity.

Protein purification using inverse phase transition of elastin-like polypeptide (ELP) domains is a useful alternative to chromatography. Genetic fusions of ELP domains to various proteins have the ability to reversibly transition between soluble monomers and micron-sized aggregates and this has been used to selectively purify many ELP fusions. Affinity domains can enhance this technology by using specific protein binding domains to enable ELP mediated affinity capture (EMAC) of proteins of interest (POI) that have been fused to corresponding affinity ligands. In this paper, we highlight the use of Src homology 3 (SH3) domains and corresponding peptide ligands in EMAC that have differential binding affinities towards SH3 for efficient capture and elution of proteins. Furthermore, differences between capture and elution of a monomeric and a multimeric protein were also studied.