Patent ID: 8853360

Claim:
An isolated polypeptide comprising a botulinum neurotoxin C1 light chain having a modified amino acid sequence relative to the amino acid sequence of a wild-type botulinum neurotoxin C1 light chain having the amino acid sequence set forth in SEQ ID NO:1, wherein the modifications comprise: (a) the amino acid substitutions L200W, M221W, and I226W; (b) the amino acid substitutions L200W, M221W, and I226H; (c) the amino acid substitutions L200W, M221W, and I226K; (d) the amino acid substitutions L200W, M221W, and I226L; (e) the amino acid substitutions L200W, K216A, S217G, E218K, M221W, and I226W; (f) the amino acid substitutions L200W, K216A, S217A, E218A, M221W, and I226W; (g) the amino acid substitutions S51T, R52N, and N53P; or (h) the amino acid substitutions F50Y, S51T, and R52N; wherein the modified botulinum neurotoxin C1 light chain is capable of selectively cleaving syntaxin protein but has substantially reduced or no activity against SNAP-25, as compared to the wild-type botulinum neurotoxin C1 light chain.