Synthesis of Chlorotoxin by Native Chemical Ligation

Chlorotoxin (CLTX) is a neurotoxin found in the venom of the Israeli scorpion, Leirius quinquestriatus . It contains 36-amino acids with four disulfide bonds and inhibits low-conductance chloride channels. CLTX also binds to matrix metalloproteinase-2 (MMP-2) selectively. The synthesis of chlorotoxin using solid phase peptide synthesis (SPPS) is very difficult and has a very low yield (<1%) due to high number of amino acid sequence. In this work, to improve the efficiency of the synthesis, native chemical ligation was applied. In this strategy, chlorotoxin sequence was split into two parts having 15 and 21 amino acids. 21-mer peptide was synthesized in its native form based on 9-fluorenylmethyloxycarbonyl (Fmoc) chemistry. 15-mer peptide was synthesized having o-aminoanilide linker on C-terminal. These parts were coupled by native chemical ligation to produce chlorotoxin.