Abstract: The present invention provides a preparation of botulinum toxin light chain type A or E, wherein the preparation is both catalytically active and soluble. Preferably, the preparation consists essentially of amino acid residues 1 through 425 of the botulinum toxin light chain type A. A method of screening inhibitors is also provided, wherein the method comprises exposing a test inhibitor to the preparation of botulinum toxin light chain type A and evaluating the biological activity of the preparation. In another embodiment, a method of providing a catalytically active, soluble preparation of botulinum toxin light chain, type A is provided, wherein the method comprises obtaining an expression vector comprising a DNA sequence encoding amino acid residues 1-425 and expressing a polypeptide.

Abstract: A hybrid botulinal neurotoxin is disclosed. In one embodiment, the neurotoxin comprises a combination of a botulinal neurotoxin heavy chain and light chain, wherein the light chain and heavy chain are not of the same serotype and wherein the heavy and light chains are linked by a homobifunctional sulfydryl linker. A method for creating hybrid neurotoxins comprised of different functional domains is also disclosed.

Abstract: A system is used to express clostridial gene constructions in a clostridial host. A mobilizable transfer plasmid is described which permits the direct transfer of the plasmid, and genes carried on it, from E. coli into Clostridium species. A promoter is described for use in clostridial species. Also, a useful host strain is used which is nontoxigenic and which permits high levels of expression of clostridial genes using the clostridial promoter.

Abstract: A hybrid botulinal neurotoxin is disclosed. In one embodiment, the neurotoxin comprises a combination of a botulinal neurotoxin heavy chain and light chain, wherein the light chain and heavy chain are not of the same serotype. A method for creating hybrid neurotoxins comprised of different functional domains is also disclosed.