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Botulinum toxins consist of two peptides linked by disulfide bonds. The heavy chain is responsible for specific binding to acetylcholine (ACh) containing
neurons. Following binding to the cell surface, the entire complex undergoes endocytosis and subsequent translocation of the light chain into the nerve cell
cytoplasm. The light chain contains a zinc-requiring endopeptidase that cleaves soluble N-ethylmaleimide sensitive factor (NSF) attachment protein
receptor (SNARE) proteins belonging to the docking/fusion complex required for neuroexocytosis of ACh. These proteins may be associated with the
synaptic vesicles (v-SNARE) or with their targets on the presynaptic membrane (t-SNARE). Botulinum toxin types A and E proteolyse the t-SNARE protein
known as synaptosomal-associated protein (SNAP)-25, and BoNT type E cleaves both SNAP-25 and syntaxin, which is attached to SNAP-25 and to the
Source: Botulism, Goldfrank's Toxicologic Emergencies, 10e
presynaptic membrane. BoNT types B, D, F, and G target the v-SNARE protein synaptobrevin. As a result of cleavage of these components of the docking
Citation:
Hoffman RS,
M, Lewin
NA,
Nelson LS, Goldfrank
LR. Goldfrank's
complex by the
endopeptidase,
AChHowland
is not released
and
neuromuscular
transmission
is impaired.Toxicologic Emergencies, 10e; 2015 Available at:
http://mhmedical.com/ Accessed: May 12, 2017
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