TsIV is a toxin from the venom of the Brazilian scorpion Tityus serrulatus which slows the inactivation of sodium channels.
TsIV is named after the scorpion from which the toxin is isolated, namely Tityus serrulatus (Ts). Alternative names for the TsIV toxin are TsIV-5, Toxin-4, Tityustoxin IV, Ts-IV and Toxin IV.
TsIV is one of a variety of toxins that can be isolated from the venom of the Brazilian scorpion T.serrulatus. This species of scorpion belongs to the family Buthidae and has a wide geographic distribution from northeastern to southeastern Brazil. [1]
The composition of TsIV determined by spectrophotometry is as follows: 11 Asp, 2 Thr, 3 Ser, 2 Glu, 3 Pro, 4 Gly, 3 Ala, 8 Cys, 2 Val, 2 Ile, 3 Leu, 8/9 Tyr, 1 His, 9 Lys, 2 Trp. The amino acid composition of TsIV also shows great similarity with those of Ts III and Ts V. Ts III has one less Lys and Ts V has an additional Lys and Gly. [2]
TsIV belongs to the family of α-scorpion toxins, which are known to bind voltage dependently to site 3, located on domain IV of the sodium channel, and thereby slow the inactivation of sodium channels. [3] [4] This toxin is active against mammals. The application of TsIV to neuroblastoma cells resulted in a slowing of inactivation and an increase in peak current without changing time to peak, leading to the shifting of both the steady-state activation and inactivation curves to more negative potentials. [5] Based on the knowledge that TsIV belongs to the family of α-toxins, it is likely that the effect of TsIV on the inactivation of sodium channels is preceded by the binding of TsIV to site 3 of the sodium channel.
The TsIV toxin, isolated from T. serrulatus venom, does not discriminate between tissue-specific sodium channel subtypes and has been found to effect sodium channels from rat ventricular myocytes, rat cortical neurons and mouse skeletal muscle cells. [5] Clinical manifestations of T. serrulatus envenoming include local pain at the site of the sting and systemic manifestations such as vomiting, profuse sweating, psychomotor agitation or restlessness, sinus tachycardia or bradycardia, arterial hypertension or hypotension, cardiac arrhythmias other than sinus tachycardia or bradycardia, cardiac failure, shock, tachypnea, pulmonary oedema and laboratory abnormalities such as leukocytosis, hyperglycaemia and increased amylase enzyme activity. [6] [7] [8] Martin et al. recorded the toxicity of TsIV as LD50 after subcutaneous (s.c.) and intracerebroventricular (i.c.v.) injection. The LD50 of TsIV per 20 g mouse was 0.4 µg for s.c. injection and 24 ng for i.c.v. injection. [2]
In clinical practice, Tityus poisoning is treated by intravenous administration of heterologous antivenoms. These antivenoms are obtained by the immunisation of horses with a mix of venoms derived from T.Serrulatus and T.Bahiensis. [9] Several preclinical studies have identified epitopes that are present in many different toxins from the T. serrulatus scorpion. This could lead to the development of an antidote that reacts with the same epitope located on these different toxins. [10] Additionally, studies examined reactivity between horse anti-Ts antisera and synthetically produced peptides that corresponded to the amino acid sequence of several Ts toxins, including TsIV. The aim of these studies was to ascertain the neutralizing potential of these antivenoms by examining their reactivity with different epitopes of T.serrulatus toxins. [11]
Delta atracotoxin is a low-molecular-weight neurotoxic polypeptide found in the venom of the Sydney funnel-web spider.
Tityustoxin is a toxin found in the venom of scorpions from the subfamily Tityinae. By binding to voltage-dependent sodium ion channels and potassium channels, they cause sialorrhea, lacrimation and rhinorrhea.
Tityus is a large genus of thick-tailed scorpions, the namesake of its subfamily Tityinae. As of 2021, Tityus contains more than 220 described species distributed in Central America and South America, from Costa Rica to Argentina. Species in the genus Tityus have been studied for hundreds of years, long before the taxonomic classification was put in place. Tityus tend to be of medium size for scorpions, roughly 50 to 70 millimeters long. They are dark brown or red in color, and can exhibit sexual dimorphism. They can live in a variety of environments, ranging from urban to arid mountains to the Amazon Rainforest. Tityus scorpions are best known for their venom and potent sting. The genus contains several dangerously venomous scorpions, the best known of which is the Brazilian yellow scorpion, T. serrulatus. Its venom can cause severe illness, and in the young, old and infirm even death. Some experts have argued that the genus as a whole may be paraphyletic, which could explain the knowledge gaps related to Tityus.
A scorpion sting is an injury caused by the stinger of a scorpion resulting in the medical condition known as scorpionism, which may vary in severity. The anatomical part of the scorpion that delivers the sting is called a "telson". In typical cases, scorpion stings usually result in pain, paresthesia, and variable swelling. In serious cases, scorpion stings may involve the envenomation of humans by toxic scorpions, which may result in extreme pain, serious illness, or even death depending on the toxicity of the venom.
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.
Tityus serrulatus, the Brazilian yellow scorpion, is a species of scorpion of the family Buthidae. It is native to Brazil, and its venom is extremely toxic. It is the most dangerous scorpion in South America and is responsible for the most fatal cases.
Tityus fasciolatus is a species of scorpion from the family Buthidae. The species are 4.5–8.5 centimetres (1.8–3.3 in) in length and are yellowish-brown coloured. They also have three dark stripes over the mesosoma with either yellowish or orange pedipalps, which have dark spots as well. Their first to third segments of metasoma is yellowish-orange, with the fourth one being reddish. Their fifth and final segment id dark red coloured. The species have yellow coloured legs which have dark spots, which are the same as on pedilap. Their tarsus is dark in colour with pectines that have 17-25 teeth, in which they have 16-18 rows of granules. T. fasciolatus is a species of medical importance, its venom is molecular and very similar to T. serrulatus, its venom contains at least 10 toxic fractions, with molecular masses ranging from 6 to 10-80 kDa, the LD50 for this species is 2.984 mg / kg.
Butantoxin (BuTX) is a compound of the venom of three Brazilian and an Argentinean scorpion species of the genus Tityus. Butantoxin reversibly blocks the voltage-gated K+ channels Shaker B and Kv1.2, and the Ca2+-activated K+ channelsKCa 1.1 and KCa 3.1.
Bactridines are a group of six antibacterial peptides from the venom of the Tityusdiscrepans scorpion. They exclusively target sodium channels. Bactridines are unique in that this scorpion toxin acts on sodium channels of both bacteria and eukaryotes.
Ts15 is produced by the Brazilian yellow scorpion Tityus serrulatus. It targets voltage-gated potassium channels, primarily the subtypes Kv1.2 and Kv1.3.
LmαTX3 is an α-scorpion toxin from Lychas mucronatus. that inhibits fast inactivation of voltage gated sodium-channels (VGSCs).
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.
Beta-mammal toxin Cn2, also known as Cn2 toxin, is a single chain β-scorpion neurotoxic peptide and the primary toxin in the venom of the Centruroides noxius Hoffmann scorpion. The toxin specifically targets mammalian Nav1.6 voltage-gated sodium channels (VGSC).
Scorpionism is defined as the accidental envenomation of humans by toxic scorpions. If the injection of venom in a human results in death, this is defined as scorpionism. This is seen all over the world but is predominantly seen in the tropical and subtropical areas. These areas include Mexico, northern South America and southeast Brazil in the Western hemisphere. In the Eastern hemisphere, scorpionism possess a public health threat in the regions of South Africa, the Middle East, and the Indian subcontinent.
Tityus pachyurus is a species of arachnid endemic to Central America and South America.
The Tst26 toxin is a voltage-gated potassium channel blocker present in the venom of Tityus stigmurus, a species of Brazilian scorpion. Tst26 selectively blocks Kv1.2 and Kv1.3 channels.
LmαTX5 is an α-scorpion toxin which inhibits the fast inactivation of voltage-gated sodium channels. It has been identified through transcriptome analysis of the venom gland of Lychas mucronatus, also known as the Chinese swimming scorpion – a scorpion species which is widely distributed in Southeast Asia.
Delta hexatoxin Hv1 is a neurotoxic component found in the venom of the Australian funnel web spider.
Ts8 TsK2; Tityustoxin K-beta; TsTX-K beta and TsTx-Kβ) is a neurotoxin present in the venom of the Brazilian yellow scorpion, Tityus serrulatus. Ts8 targets voltage-gated potassium channels, by selective inhibition of the Kv4.2 channels.
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