Chlorotoxin

Chlorotoxin (CTX) is one of the most well-studied scorpion venom peptides that contain 36 amino acids, and responsible for blocking small conductance chloride ion channels. It was initially purified from the venom of the death hunter scorpion (Leiurus quinquestriatus). The superfamily of scorpion toxins includes CTX, which is a small positive charged peptide with 8 cysteines connected with four disulfide bonds. CTX has the ability to selectively bind to matrix-metalloproteinase receptor on glioma cells and inhibit it. It has been shown that the chloride channels can be effectively blocked by chlorotoxin as a ligand of theirs.

Due to CTX is able to bind preferentially to glioma cells rather than non-neoplastic cells or normal brain, it has been exploited to develop innovative ways for the treatment and diagnostics of several types of cancer. Recently, cancer cells have been distinguished from surrounding normal cells via CTX: Cy5.5 bioconjugate. This increases the probability that all of the cancerous cells will be removed by surgeons without endangering the surrounding healthy tissue.