Figure 2. (A) Fractionation of the crude toxin preparation by anion exchange chromatography on a 1 X 7 cm Source 15Q column at pH 5.5. Tca and Tcb represent the major complexes in the crude fraction. Subsequent purifications were performed with the same column at pH 7.5. In one preparation, after prolonged storage at pH 5.5, TcaAiii was separated from the parent Tca (B).