Botulinum toxins

5:29 PM // 0 comments // sb blogger // Category: Biological Toxins , Botulinum , toxins , Weapons //

Botulinum toxin acts by binding presynaptically to high-affinity recognition sites on the cholinergic nerve terminals and decreasing the release of acetylcholine, causing a neuromuscular blocking effect. This

mechanism laid the foundation for the development of the toxin as a therapeutic tool.

Recovery occurs through proximal axonal sprouting and muscle re-innervation by formation of a new neuromuscular junction. De Paiva and colleagues suggest that eventually the original neuromuscular junction

regenerates.

BoNT-A and BoNT-E cleave synaptosome-associated protein (SNAP-25), a presynaptic membrane protein required for fusion of neurotransmitter-containing vesicles.
BoNT-B, BoNT-D, and BoNT-F cleave a vesicle-associated membrane protein (VAMP), also known as synaptobrevin.
BoNT-C acts by cleaving syntaxin, a target membrane protein.

Table 1. Botulinum Toxin Types, Target Sites, Discoverers, and Year Discovered

Type	Target	Discoverer	Year
A	SNAP-25	Landman	1904
B	VAMP	Ermengem	1897
C1	Syntaxin	Bengston and Seldon	1922
D	VAMP	Robinson	1929
E	SNAP-25	Gunnison	1936
F	VAMP	Moller and Scheibel	1960
G	VAMP	Gimenez and Ciccarelli	1970