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BTX: Structure and function

BTX: Structure and function

Seven different serotypes of BTX exist and are labeled A, B, C1, D, E, F, and G. All serotypes exhibit a similar molecular structure. The toxin is produced as an inactive 150 kiloDalton (kDa) single chain protein that undergoes tissue proteolysis to form a 100- kDa heavy chain and a 50-kDa light chain which serves as a zinc-dependent protease. This di-chain complex is held together by a disulfide bond. The active molecule has a variety of different effects including inhibition of the presynaptic neuromuscular junction, alteration of fibroblast function, and modification of skin mechanical properties.