Charybdotoxin is a 37 amino acid

Amino acid

Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...

 neurotoxin

Neurotoxin

A neurotoxin is a toxin that acts specifically on nerve cells , usually by interacting with membrane proteins such as ion channels. Some sources are more general, and define the effect of neurotoxins as occurring at nerve tissue...

 from the venom of the scorpion

Scorpion

Scorpions are predatory arthropod animals of the order Scorpiones within the class Arachnida. They have eight legs and are easily recognized by the pair of grasping claws and the narrow, segmented tail, often carried in a characteristic forward curve over the back, ending with a venomous stinger...

 Leiurus quinquestriatus hebraeus

Deathstalker

The deathstalker , is a species of scorpion, a member of the Buthidae family. It is also known as Palestine yellow scorpion, Omdurman scorpion, Israeli desert scorpion and numerous other colloquial names, which generally originate from the commercial captive trade of the animal...

that blocks calcium-activated potassium channels. This blockade causes hyperexcitability of the nervous system.

Chemical properties

Scorpions such as the deathstalker

Deathstalker

The deathstalker , is a species of scorpion, a member of the Buthidae family. It is also known as Palestine yellow scorpion, Omdurman scorpion, Israeli desert scorpion and numerous other colloquial names, which generally originate from the commercial captive trade of the animal...

 paralyze their prey by injecting a potent mix of peptide toxins. Charybdotoxin (CTX), a 37 amino acid neurotoxin, is one of the peptide toxins that can be extracted from the venom of the scorpion. Its structure is very similar to that of margatoxin

Margatoxin

Margatoxin is a peptide that selectively inhibits Kv1.3 voltage-dependent potassium channels. It is found in the venom of Centruroides margaritatus, also known as the Central American Bark Scorpion. Margatoxin was first discovered in 1993...

. Charybdotoxin contains three disulfide bridges.

Mode of action

Charybdotoxin occludes the pore of calcium-activated voltage-gated K+ channels by binding to one of four independent, overlapping binding sites. It binds both to the open and the closed states. In addition, the block is enhanced as the ionic strength is lowered. The blockade of K+ channels by the charybdotoxin peptide causes neuronal hyperexcitability.

Treatment

Anti-scorpion venom serum (AScVS) is an effective and safe method of therapy in severe scorpion envenoming syndrome. Compared with other therapies like alpha blockers it has a relatively short recovery period (10 vs 16–42 hours).