The protease can be light chain Clostridium botulinum toxin; proteolytically active fragment of the light chain of a Clostridium botulinum toxin containing an amino acid sequence His-Xaa-Xaa-Xaa-His-Xaa-Xaa-His wherein Xaa is an amino acid; light chain of the tetanus toxin; proteolytically active fragment of the light chain of the tetanus toxin containing His-Asp-Leu-lIe-His-Val-Leu-His;
IgA protease of Neisseria gonorrhoeae; and proteolytic domain of the
IgA protease of Neisseria gonorrhoeae.