| abstract |
The invention relates to a modified botulinum toxin comprising a natural heavy chain and a modified light chain, characterized in that the modification of the light chain resides in that it comprises (i) an extension of the chain on its N-terminus which has the structure -(C) n -(tag) m -(X) l - in the direction from the N- to the C-terminal end, whereinn C represents a cysteine residue, tag represents any tag and X represents the residue of any naturally occurring amino acid, n represents an integer from 1 to 50, m represents 0 or 1, and l represents 0 or an integer from 1 to 50,n nand in that (ii) at least one of the cysteine residues in the extension of the chain is coupled to at least one chain of PEG. |