Purification and binding characterization of a multidomain Vβ fusion protein specific for staphylococcal enterotoxin B (SEB) and toxic shock syndrome toxin–1 (TSST-1). A, Diagram of the single-chain construct. B, SDS-PAGE gel of individual Vβ domains and the fusion protein. C, Thermal stabilities of the individual Vβ proteins and the fusion protein determined using circular dichroism. D, Competition ELISA of SEB binding. E, Competition ELISA of TSST-1 binding. F, Direct binding ELISA with SEB absorbed to wells, followed by the fusion protein, followed by biotinylated TSST-1. G, Surface plasmon resonance (SPR) analysis of the Vβ fusion–SEB interaction. H, SPR analysis of the Vβ fusion–TSST-1 interaction. Details of the procedures are described in the appendix, which is available only in the electronic version. RU, resonance units.