What is the most lethal toxin?
40172#0
Botulinum toxin (BTX) is a neurotoxic protein produced by the bacterium "Clostridium botulinum" and related species. It prevents the release of the neurotransmitter acetylcholine from axon endings at the neuromuscular junction and thus causes flaccid paralysis. Infection with the bacterium causes the disease botulism. The toxin is also used commercially in medicine, cosmetics and research.
Botulinum is the most acutely lethal toxin known, with an estimated human median lethal dose (LD) of 1.3–2.1 ng/kg intravenously or intramuscularly and 10–13 ng/kg when inhaled.
Botulinum toxin
42467934#2
Botulinum toxin is the most acutely lethal toxin that is known. It is produced by the bacterium clostridium botulinum. It acts inside nerve terminals by decreasing the release of acetylcholine, blocking neuromuscular transmission and thereby causing flaccid muscular paralysis. As a result, the muscle is weakened for about 3 to 4 months.
Botulinum toxin therapy of strabismus
43922#1
The botulinum toxin can cause a severe flaccid paralytic disease in humans and other animals and is the most potent toxin known to mankind, natural or synthetic, with a lethal dose of 1.3–2.1 ng/kg in humans.
Clostridium botulinum
57019614#0
The Lethal Toxin Neutralizing Factor, or LTNF, is a protein found in the blood serum of opossum. The North American Opossum ("Didelphis virginiana") is notable for its ability to survive snake bites. The protein could potentially be used to treat most snake bites as it is capable of neutralizing the venom of major snake families. Furthermore, most modern antivenoms come from horse proteins to which many people are allergic. The molecular weight of LTNF is about 63 kDa.
Lethal toxin neutralizing factor
29540195#0
"Clostridium perfringens" beta toxin is one of the four major lethal toxins produced by "Clostridium perfringens" Type B and Type C strains. It is a necrotizing agent and it induces hypertension by release of catecholamine. It has been shown to cause necrotic enteritis in mammals and induces necrotizing intestinal lesions in the rabbit ileal loop model. "C. perfringens" beta toxin is susceptible to breakdown by proteolytic enzymes, particularly trypsin. Beta toxin is therefore highly lethal to infant mammals because of trypsin inhibitors present in the colostrum.
Clostridium perfringens beta toxin
48189062#9
The toxin has been implicated in cases of respiratory irritation, inflammation of the eye and severe contact dermatitis in fishermen. Antillatoxin is a very potent neurotoxin, although exact toxicity differs between species. The lethal concentration LC is about 0.1 µM for goldfish, making it the most potent toxin known for goldfish after brevetoxin. It can be cytotoxic to single cerebellar granule cells at concentrations as low as 20 nM in rats but more typically at 50 nM.
Antillatoxin
4977075#9
The venom of this species varies very little among Japan, China, and Korea in terms of both its potency and its effects. According to Yoshimitsu (2005), this species and the Okinawan habu, another pitviper, are the most venomous snakes in Japan. The venom's lethality as measured by LD in mice following intraperitoneal injection is in the range 0.3 mg/kg to 1.22 mg/kg. The venom mostly contains haemolytic toxins, but it also has two neurotoxins—an alpha-toxin that is a post-synaptic inhibitor and a beta-toxin that is a pre-synaptic inhibitor. Because the beta-toxin acts pre-synaptically, its effects cannot be blocked or treated by anticholinesterases. The venom contains an anticoagulant, mamushi L-amino-acid oxidase (M-LAO). It also contains the peptide ablomin which is highly similar in amino acid sequence to that of the venom, helothermine, of the beaded lizard ("Heloderma horridum").
Mamushi
14168475#9
Initial studies of mutants revealed that residues on the back side of the central alpha helix were required for super antigenic activity. Changing the histidine at position 135 to alanine caused TSST-1 to be neither lethal or superantigenic. Changes in residues that were in close proximity to H135A, also had the effect of diminishing the lethality and superantigenic quality of these mutants. Although most of these mutants did not result in loss of antigenicity of TSST-1. Tests done using mutagenic TSST-1 toxins indicated that the lethal and superantigenic properties are separable. When Lys-132 in TSST-O was changed to a Glu, the resulting mutant became completely lethal but non superantigenic. The same results, lethal but not superantigenic, were found for TSST-1 Gly16Val. Residues Gly16, Glu132,and Gln 136, located on the back of the back-side groove of the putative TCR binding region of TSST-1, it has been proposed that they are also a part of a second functionally lethal site in the TSST-1.
Toxic shock syndrome toxin
36122052#0
Verrucarin A belongs in the class of trichothecenes, a group of sesquiterpene toxins produced by several fungi, namely from the "Fusarium" species, that are responsible for infecting food grains. 
Within the skeleton of the basic trichothecane structure, the olefin and epoxide are crucial for toxicity; ester functionalities and hydroxyl groups often contribute to the toxicity, thereby rendering Verrucarin A as one of the most lethal examples. The mechanism of action for this class of toxins mainly inhibits protein biosynthesis by preventing peptidyl transferase activity. Although initially thought to be potentially useful as anticancer therapeutics, numerous examples of trichothecene derivatives were shown to be too toxic for clinical use.
Verrucarin A
29070604#0
Anthrax lethal factor endopeptidase (, "lethal toxin") is an enzyme that catalyzes the hydrolysis of mitogen-activated protein kinase kinases. This enzyme is a component of the lethal factor produced by the bacterium "Bacillus anthracis". The preferred cleavage site can be denoted by BBBBxHxH, in which B denotes a basic amino acid Arg or Lys, H denotes a hydrophobic amino acid, and x is any amino acid.
Anthrax lethal factor endopeptidase