Botulinumtoxiner

Botulinumtoxiner is a neurotoxic protein complex produced by anaerobic, spore‑forming bacteria of the genus Clostridium. The toxin is a metalloprotease that interferes with the release of acetylcholine at neuromuscular junctions, causing flaccid paralysis of the affected muscles. The two most clinically relevant species, Clostridium botulinum and Clostridium baratii, secrete the toxin as a complex of two or three polypeptide chains linked by non‑covalent interactions. The active form is a 150‑kDa protein that is cleaved by proteases during absorption in the gut, yielding a 150‑kDa catalytic component that is transported into neurons.

Botulinumtoxiner has seven serologically distinct types, A through G, with type A being the most potent and most frequently associated with human disease. The toxin’s mechanism of action involves the proteolytic cleavage of SNARE proteins such as SNAP‑25, syntaxin, and VAMP, which are essential for synaptic vesicle docking and neurotransmitter release. By inhibiting acetylcholine exocytosis, the toxin produces a characteristic flaccid paralysis.

Because of its potency, botulinumtoxiner is a major cause of food‑borne botulism, which manifests as a descending paralysis, starting with cranial nerve deficits and progressing to respiratory failure. Despite its notoriety as a bioterror agent, the protein has been harnessed therapeutically. Purified preparations of serotype A and B are used in dermatology, neurology and for cosmetic purposes under brand names such as Botox. In addition, doses of the toxin are employed to manage spasticity, chronic migraine, hyperhidrosis and certain bladder disorders.

Research into botulinumtoxiner continues to explore its molecular structure, sub‑toxin variants, and potential use in targeted drug delivery, as well as the development of neutralizing antibodies and small‑molecule inhibitors. The clinical utility of the toxin is counterbalanced by stringent regulation and the need for careful dosage to avoid systemic toxicity.