| abstract |
The invention relates to a modified botulinum toxin which has a naturally occurring heavy chain and a modified light chain. The invention is characterized in that the modification of the light chain is that it comprises (i) on its N terminus an extension of the chain which has the structure -(C)<SUB>n</SUB>-(tag)<SUB>m</SUB>-(X)<SUB>l</SUB>- in the direction from the N terminus to the C terminus, C representing a cysteine group, tag representing any tag and X representing a group of any naturally occurring amino acid, n being an integer from 1 to 50, m being 0 or 1 and l being 0 or an integer from 1 to 50, and (ii) that at least one of the cystein groups in the extension of the chain is coupled to at least one chain PEG. |