Abstract: The present invention relates to the field of affinity purification and provides for means and methods applying protein binding agents competing for a target protein for use as capture and elution tool, wherein the elution agent comprises an immunoglobulin single variable domain (ISVD), and is capable of displacing the capturing binding agent. More specifically, the displacement efficiency of the ISVD-containing protein binding agent is driven by its dissociation kinetics, with a rate constant of dissociation (koff) equal or lower as compared to the capturing agent. Furthermore, said protein binding agents are deployable in high-throughput purification from complex mixtures, or for capturing protein-complexes, thereby facilitating structural, biochemical and physicochemical analysis of said target proteins.

Abstract: The present invention relates to the field of structural biology. More specifically, the present invention relates to novel fusion proteins, their uses and methods in three-dimensional structural analysis of macromolecules, such as X-ray crystallography and high-resolution Cryo-EM, and their use in structure-based drug design and screening. Even more specifically, the invention relates to a functional fusion protein of a cytokine and a scaffold protein wherein the scaffold is a folded protein that interrupts the topology of the cytokine to form a rigid fusion protein that retains its receptor binding and activation capacity. More specifically, chemokine- and interleukin-based functional fusion proteins, and their production and uses, are disclosed herein.