FIG. 1.
Purification of recombinant HCR/A1. (A) BoNT/A1 is cleaved by Clostridial proteases into a dichain toxin that are linked by a disulfide bond. The N-terminal light chain encodes a zinc protease. The C-terminal heavy chain includes a translocation domain (HCT), and a C-terminal receptor binding domain which can be subdivided into an N-terminal (HCRN) and C-terminal domain (denoted ΔA). (B) rHCR/A1 was purified from E. coli cell paste by a three-column strategy. The clarified extract was purified sequentially using nickel affinity, gel filtration and ion exchange chromatography. rHCR/A (5 μg) was separated by SDS-PAGE under reducing conditions and visualized by staining with silver.