The present invention is concerned with modified neurotoxins. Specifically, it relates to a modified biologically active neurotoxin polypeptide comprising at least one poly-Glycine domain. Also contemplated is a polynucleotide encoding the modified neurotoxin polypeptide having a poly-Glycine domain fused to the N-terminus, to the C-terminus or to both of the heavy and/or light chain of the mature neurotoxin polypeptide, vector comprising it and a host cell comprising such a polynucleotide or a vector. Moreover, envisaged are the aforementioned compounds for use as a medicament for treating various diseases.
