Bungarotoxin
Bungarotoxins are toxins found in the venom of snakes and kraits. Bites from these animals can result in severe symptoms including bleeding or hemorrhage, paralysis and tissue damage that can result in amputation. The paralytic effects of venom are particularly dangerous as they can impair breathing.[1] These symptoms are the result of bungarotoxin presence in the venom. In actuality, venom contains several distinct bungarotoxins, each varying in which receptors they act on and how powerful they are.
History
Bungarotoxins are a group of closely related
The four characterized toxins are:
- α-Bungarotoxin
- β-Bungarotoxin(not a three-finger toxin)
- γ-Bungarotoxin (Q9YGJ0)
- k-Bungarotoxin
Snake bites
Research involving bungarotoxins has been significant in improving our understanding of
Toxin mechanism
Bungarotoxins function by modulating acetylcholine neurotransmission in both muscles and neurons. α-Bungarotoxin irreversibly blocks the binding of acetylcholine (ACh) to postsynaptic nicotinic acetylcholine receptors (nAchR) on both muscle and neurons. In addition to being found in the venom of kraits, it is also in venoms of the elapids and sea snakes.[9] Similarly, κ-bungarotoxin acts to block postsynaptic nAchRs, but its effect is primarily on neuronal receptors rather than muscular nicotinic receptors. Conversely, β- and γ-bungarotoxins act presynaptically to cause excessive acetylcholine release and subsequent depletion, resulting in paralysis.[9]
Structure
The three-finger protein family is a family of proteins that share similar 3-dimensional structure. They are found in a wide variety of organisms including snakes. In snakes and kraits, venomous toxins largely consist of those with a three-finger structure.[10] The structure of the α-BTX has been most studied; its three-finger structure consists of a hydrophobic globular core from which 3 beta-pleated-sheet loops extend as well as a C-terminus.[9] Within the family of three-finger α-neurotoxins, the protein structure is further subcategorized as short chain, long chain, atypical long chain and non conventional α-neurotoxins. This subclassification describes additional structural aspects of the toxin as well as the receptors they act on. For example, α-BTX is a long chain toxin meaning it is composed of 66-70 amino acids and possesses a three-finger structure. Long chain toxins act on nAchR in both muscle and neurons whereas short chain α-neurotoxins act on nAchR in muscle only.[9] While all α-neurotoxins of the three-finger family will act on muscle nAchR, these differences in structure determine selectivity of the toxin for its receptor as well as affinity and dissociation.[10]
References
- ISBN 978-1-4160-4928-9, retrieved 2021-12-25
- ^ Bungarotoxins at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
- ^ ISBN 978-1-4160-4928-9, retrieved 2021-12-25
- S2CID 84443027.
- S2CID 20028814.
- S2CID 220773156.
- ^ a b c d "Snakebite envenoming". www.who.int. Retrieved 2021-12-25.
- ISBN 978-1-4160-4928-9, retrieved 2021-12-25
- ^ ISBN 978-1-4160-4928-9, retrieved 2021-12-25
- ^ S2CID 220773156.