Peptide phage display library as source for inhibitors of clostridial neurotoxins

Clostridial neurotoxins are the most powerful toxins known. There are no av ailable antidotes to neutralize neurotoxins after they have been internaliz ed by neuronal cells. Enzymatic domains of clostridial neurotoxins are zinc endopeptidases specific for protein components of the neuroexocytosis appa ratus. Thus, attempts were made to find such antidotes among molecules poss essing chelating properties. Subsequently, it was proposed that the process of interaction between clostridial neurotoxins and their substrates might be more complex than viewed previously and may include several separate reg ions of interaction. Phage display technology is free fi-om bias toward any particular model. This technology in combination with recombinantly produc ed light chains of botulinum neurotoxins serotypes A, B, and C was used to identify potential inhibitors of clostridial neurotoxins. Identified sequen ces did not show substantial similarity with substrate proteins of clostrid ial neurotoxins. Nevertheless, three peptides chosen for further analysis w ere able to inhibit enzymatic activity of all clostridial neurotoxins teste d. This work demonstrates that at least one of these peptides could not be cleaved by clostridial neurotoxin. Attempts to delete amino acid residues f rom this peptide resulted in dramatic loss of its inhibitory activity. Fina lly, this work presents a novel approach to searching for inhibitors of clo stridial neurotoxins.