Patent ID: 8003351

Claim:
A cleavable single-chain polypeptide comprising: a) a first region comprising a botulinum neurotoxin serotype A heavy chain binding element able to preferentially interact with a target cell surface marker under physiological conditions; b) a second region comprising a botulinum neurotoxin serotype A heavy chain translocation element able to facilitate the transfer of said single-chain polypeptide across a vesicular membrane; c) a third region comprising a botulinum neurotoxin serotype A light chain therapeutic element having SNAP-25 sequence-specific endopeptidase activity, and d) a fourth region comprising a protease cleavage site cleaved by a non-human Enterokinase; wherein said fourth region intervenes between said first region and said second region, between said second region and said third region, or between said first region and said third region.