Dortoxin (also called dorsotoxin [1] ) is a lethal peptide toxin which is secreted by the South African spitting scorpion Parabuthus transvaalicus . Injection of pure dortoxin in mice leads to hyperactivity that lasts until death. [2]
Dortoxin is a lethal peptide in the venom that is secreted by Parabuthus transvaalicus . Other toxins in its venom include bestoxin and altitoxin. At least 20% of the peptides in the venom of P. transvaalicus consists of these three toxins, and they are thought to be responsible for most of its toxic potency. [2]
Dortoxin is a lethal member of the birtoxin family. Apart from its slightly smaller chain length and lower number of disulfide bridges, the toxin has large homology to members of the group of long chain neurotoxins. Dortoxin has a chain length of 58 amino acids and contains three disulfide bridges, whereas long chain neurotoxins generally have a chain length of 60-70 amino acids and contain four disulfide bridges. [1] Dortoxin has a molecular mass of 6641.4 Da. [2]
On the basis of its structural homology to members of the beta group of long chain neurotoxins, dortoxin may bind to voltage-gated sodium channels. [2] However, electrophysiological tests have not yet been performed.
Injection of pure dortoxin in mice leads to hyperactivity, tremors, convulsions, profuse salivation, lacrimation, continuous urination and vocalizations. The toxin has a rapid onset. The last period of hyperactivity is more intense and leads to death, after which postmortem twitching occurs for at least 30 seconds. The toxin is lethal at 200 ng of peptide in a 20 g mouse. [2]
Delta atracotoxin is a low-molecular-weight neurotoxic polypeptide found in the venom of the Sydney funnel-web spider.
Birtoxin is a neurotoxin from the venom of the South African Spitting scorpion. By changing sodium channel activation, the toxin promotes spontaneous and repetitive firing much like pyrethroid insecticides do
Bestoxin is a neurotoxin from the venom of the South African spitting scorpion Parabuthus transvaalicus. Most likely, it targets sodium channel function, thus promoting spontaneous and repetitive neuronal firing. Following injection into mice, it causes non-lethal writhing behaviour.
Altitoxin is a neurotoxin found in the South African scorpion Parabuthus transvaalicus. Injection of altitoxin in mice leads to akinesia, depression and death.
Ikitoxin is a neurotoxin from the venom of the South African Spitting scorpion that targets voltage-sensitive sodium channels. It causes unprovoked jumps in mice following intracerebroventricular injections.
α-Neurotoxins are a group of neurotoxic peptides found in the venom of snakes in the families Elapidae and Hydrophiidae. They can cause paralysis, respiratory failure, and death. Members of the three-finger toxin protein family, they are antagonists of post-synaptic nicotinic acetylcholine receptors (nAChRs) in the neuromuscular synapse that bind competitively and irreversibly, preventing synaptic acetylcholine (ACh) from opening the ion channel. Over 100 α-neurotoxins have been identified and sequenced.
Huwentoxins (HWTX) are a group of neurotoxic peptides found in the venom of the Chinese bird spider Haplopelma schmidti. The species was formerly known as Haplopelma huwenum, Ornithoctonus huwena and Selenocosmia huwena. While structural similarity can be found among several of these toxins, HWTX as a group possess high functional diversity.
Covalitoxin-II is a peptide toxin that is produced by the spider Coremiocnemis validus. It can induce excitatory, non-lethal behavioral symptoms like quivering and jerking in crickets.
CSTX is a name given to a group of closely related neurotoxic peptides present in the venom of the wandering spider Cupiennius salei. There are twenty types so far described for this protein group. However, some are reclassified into cupiennins group of toxin, including CSTX-3, -4, -5, and -6, because of their chemical affinity. The first thirteen were isolated and identified in 1994 by Lucia Kuhn-Nentwig, Johann Schaller, and Wolfgang Nentwig of the Zoological Institute at the University of Bern, Switzerland. The different types are most likely the products of splicing variant of the same gene. They are all L-type calcium channel blockers, and also exhibit cytolytic activity by forming an alpha-helix across the cell membrane in mammalian neurons. They also inhibit voltage-gated calcium channels in insect neurons.
Oxotoxins, or oxytoxins, are a group of neurotoxins present in the venom of lynx spiders belonging to the genus Oxyopes, hence the name oxytoxin. They are disulfide-rich peptides. Only two types are so far reported from two different species, the larger oxytoxin 1 (OxyTx1) from Oxyopes kitabensis, and the smaller oxytoxin 2 (OxyTx2) from Oxyopes lineatus. OxyTx1, the first known oxytoxin, was discovered in 2002. It was found to enhance the lethal efficacy of the spider venom by acting together with oxyopinins. It is composed of 69 amino acid residue, which are cross-linked by five disulfide bridges. It is a large peptide having a molecular mass of 8059.2 Da; but shows the size of 9,109.4 Da due to the presence of disulfide bridges. It is a potent insecticide, but non-toxic to mice up to 1 μg/20-g mouse. It acts synergistically with oxyopinins of the same venom to increase the insecticidal effect.
Halcurin is a polypeptide neurotoxin from the sea anemone Halcurias sp. Based on sequence homology to type 1 and type 2 sea anemone toxins it is thought to delay channel inactivation by binding to the extracellular site 3 on the voltage gated sodium channels in a membrane potential-dependent manner.
Anuroctoxin is a peptide from the venom of the Mexican scorpion Anuroctonus phaiodactylus. This neurotoxin belongs to the alpha family of potassium channel acting peptides. It is a high-affinity blocker of Kv1.3 channels.
HsTx1 is a toxin from the venom of the scorpion Heterometrus spinifer. HsTx1 is a very potent inhibitor of the rat Kv1.3 voltage-gated potassium channel.
Spinoxin is a 34-residue peptide neurotoxin isolated from the venom of the Malaysian black scorpion Heterometrus spinifer. It is part of the α-KTx6 subfamily and exerts its effects by inhibiting voltage-gated potassium channels, specifically Kv1.2 and Kv1.3.
Tityustoxin peptide 2 (TsPep2) is a peptide isolated from the venom of the Tityus serrulatus. It belongs to a class of short peptides, together with Tityustoxin peptide 1 and Tityustoxin peptide 3.
BmP02, also known as α-KTx 9.1 or Bmkk(6), is a toxin from the Buthus Martensi Karsch (BmK) scorpion. The toxin acts on potassium channels, blocking Kv1.3 and slowing the deactivation of Kv4.2. BmP02 is not toxic to humans or mice.
Long neurotoxin 1 (LNTX-1) is a neurotoxin that binds antagonistically to all types of muscular and neuronal nicotinic acetylcholine receptors. LNTX-1 is found in the venom of the king cobra.
MeuKTX, which belongs to the α-KTx toxin subfamily, is a neurotoxin present in the venom of Mesobuthus eupeus. This short-chain peptide blocks potassium channels, such as Kv1.1, Kv1.2 and Kv1.3.
GiTx1 (β/κ-theraphotoxin-Gi1a) is a peptide toxin present in the venom of Grammostola iheringi. It reduces both inward and outward currents by blocking voltage-gated sodium and potassium channels, respectively.
U7-ctenitoxin-Pn1a (or U7-CNTX-Pn1a for short) is a neurotoxin that blocks TRPV1 channels, and can exhibit analgestic effects. It is naturally found in the venom of Phoneutria nigriventer.