How do anti toxins work?
Addiction module
The antitoxin is generally less stable than the toxin due to its degradation by proteases already present in the cell. For example, in the ccdAB proteic addiction module, the "Lon" protease  degrades the antitoxin, but also serves many unrelated proteolytic roles, such as degrading oxidated mitochondrial products. This may indicate that the development of these addiction molecules "co-opted" existing cell utilities.
The antitoxin in proteic addiction modules functions by binding directly to the toxin and preventing its mode of action. Once the antitoxin has bound to the toxin, the toxin prevents the proteases normally responsible for degrading antitoxin to do so, maintaining the neutralization of that individual toxin molecule.
Defensin
The mammalian defensins (Table below) are different from arthropod defensins. The latter are more similar to protein scorpion toxins. Subsequent investigations confirmed relationships between scorpion toxins that block potassium channels and insect defensins in their three-dimensional structure and their disruption of membrane functions of invasive microbes. Experimental deletion of a small loop of a defensin molecule from a Hymenopteran parasitoid venom that shares attributes of scorpion toxin, removed steric hindrance of interactions between peptides and channels. The resulting peptide was neurotoxin that selectively inhibited potassium channels, binding to the channels in the same manner as scorpion toxins. The results presented structural and functional evidence for the basis of toxin evolution.
Detoxification
Certain approaches in alternative medicine claim to remove "toxins" from the body through herbal, electrical or electromagnetic treatments. These toxins are undefined and have no scientific basis, making the validity of such techniques questionable. There is little evidence for toxic accumulation in these cases, as the liver and kidneys automatically detoxify and excrete many toxic materials including metabolic wastes. Under this theory if toxins are too rapidly released without being safely eliminated (such as when metabolizing fat that stores toxins) they can damage the body and cause malaise. Therapies include contrast showers, detoxification foot pads, oil pulling, Gerson therapy, snake-stones, body cleansing, Scientology's Purification Rundown, water fasting, and metabolic therapy.
Anti-tetanus immunoglobulin
Anti-tetanus immunoglobulin, also known as tetanus immune globulin (TIG) and tetanus antitoxin, is a medication made up of antibodies against the tetanus toxin. It is used to prevent tetanus in those who have a wound that is at high risk and have not been fully vaccinated with tetanus toxoid. It is also used to treat tetanus along with antibiotics and muscle relaxants. It is given by injection into a muscle.
Common side effects include pain at the site of injection and fever. Allergic reactions including anaphylaxis may rarely occur. There is also a very low risk of the spread of infections such as viral hepatitis and HIV/AIDS with the human version. Use during pregnancy is deemed acceptable. It is made from either human or horse blood plasma.
Use of the horse version became common in the 1910s, while the human version came into frequent use in the 1960s. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. The wholesale cost in the developing world for the horse version is about US$0.90–3.60 per 1500 iu vial, while the human version is US$10.00–46.86 for 250 iu. The human version may be unavailable in the developing world. In the United States a course of treatment costs about $100–200. The horse version is not typically used in the developed world due to the risk of serum sickness.
Microbial toxin
Bacteria generate toxins which can be classified as either exotoxins or endotoxins. Exotoxins are generated and actively secreted; endotoxins remain part of the bacteria. Usually, an endotoxin is part of the bacterial outer membrane, and it is not released until the bacterium is killed by the immune system. The body's response to an endotoxin can involve severe inflammation. In general, the inflammation process is usually considered beneficial to the infected host, but if the reaction is severe enough, it can lead to sepsis.
Wrinkle
Botulinum toxin is a neurotoxin protein produced by the bacterium "Clostridium botulinum". Botox is a specific form of botulinum toxin manufactured by Allergan for both therapeutic and cosmetic use. Besides its cosmetic application, Botox is used in the treatment of other conditions including migraine headache and cervical dystonia (spasmodic torticollis) (a neuromuscular disorder involving the head and neck).
Addiction module
Addiction modules are toxin-antitoxin systems. Each consists of a pair of genes that specify two components: a stable toxin and an unstable antitoxin that interferes with the lethal action of the toxin. Found first in E. coli on low copy number plasmids, addiction modules are responsible for a process called the postsegregational killing effect. When bacteria lose these plasmid(s) (or other extrachromosomal elements), the cured cells are selectively killed because the unstable antitoxin is degraded faster than the more stable toxin. The term "addiction" is used because the cell depends on the de novo synthesis of the antitoxin for cell survival. Thus, addiction modules are implicated in maintaining the stability of extrachromosomal elements.
Antidote
The antidotes for some particular toxins are manufactured by injecting the toxin into an animal in small doses and extracting the resulting antibodies from the host animals' blood. This results in an antivenom that can be used to counteract venom produced by certain species of snakes, spiders, and other venomous animals. Some animal venoms, especially those produced by arthropods (e.g., certain spiders, scorpions, bees, etc.) are only potentially lethal when they provoke allergic reactions and induce anaphylactic shock; as such, there is no "antidote" for these venoms because it is not a form of poisoning and anaphylactic shock can be treated (e.g., by the use of epinephrine).
Serum sickness
Avoidance of antitoxins that may cause serum sickness is the best way to prevent serum sickness. Although, sometimes, the benefits outweigh the risks in the case of a life-threatening bite or sting. Prophylactic antihistamines or corticosteroids may be used concomitant with the antitoxin. Skin testing may be done beforehand in order to identify individuals who may be at risk of a reaction. Physicians should make their patients aware of the drugs or antitoxins to which they are allergic if there is a reaction. The physician will then choose an alternate antitoxin if it's appropriate or continue with prophylactic measures.
Spindle poison
Two specific families of antimitotic agents — vinca alkaloids and taxanes — interrupt the cell’s division by the agitation of microtubule dynamics. The vinca alkaloids work by causing the inhibition of the polymerization of tubulin into microtubules, resulting in the G2/M arrest within the cell cycle and eventually cell death. In contrast, the taxanes arrest the mitotic cell cycle by stabilizing microtubules against depolymerization. Even though numerous other spindle proteins exist that could be the target of novel chemotherapeutics, tubulin-binding agents are the only types in clinical use. Agents that affect the motor proteinkinesin are beginning to enter clinical trials. Another type, paclitaxel, acts by attaching to tubulin within existing microtubules. Next, it stabilizes the polymer.
Glutathione S-transferase
The compounds targeted in this manner by GSTs encompass a diverse range of environmental or otherwise exogenous toxins, including chemotherapeutic agents and other drugs, pesticides, herbicides, carcinogens, and variably-derived epoxides; indeed, GSTs are responsible for the conjugation of β-8,9-epoxide, a reactive intermediate formed from aflatoxin B, which is a crucial means of protection against the toxin in rodents. The detoxification reactions comprise the first four steps of mercapturic acid synthesis, with the conjugation to GSH serving to make the substrates more soluble and allowing them to be removed from the cell by transporters such as multidrug resistance-associated protein 1 (MRP1). After export, the conjugation products are converted into mercapturic acids and excreted via the urine or bile.
Anthrax toxin
Anthrax toxin is a three-protein exotoxin secreted by virulent strains of the bacterium, "Bacillus anthracis"—the causative agent of anthrax. The toxin was first discovered by Harry Smith in 1954. Anthrax toxin is composed of a cell-binding protein, known as protective antigen (PA), and two enzyme components, called edema factor (EF) and lethal factor (LF). These three protein components act together to impart their physiological effects. Assembled complexes containing the toxin components are endocytosed. In the endosome, the enzymatic components of the toxin translocate into the cytoplasm of a target cell. Once in the cytosol, the enzymatic components of the toxin disrupts various immune cell functions, namely cellular signaling and cell migration. The toxin may even induce cell lysis, as is observed for macrophage cells. Anthrax toxin allows the bacteria to evade the immune system, proliferate, and ultimately kill the host animal. Research on anthrax toxin also provides insight into the generation of macromolecular assemblies, and on protein translocation, pore formation, endocytosis, and other biochemical processes.
Antioxidant
Early research on the role of antioxidants in biology focused on their use in preventing the oxidation of unsaturated fats, which is the cause of rancidity. Antioxidant activity could be measured simply by placing the fat in a closed container with oxygen and measuring the rate of oxygen consumption. However, it was the identification of vitamins C and E as antioxidants that revolutionized the field and led to the realization of the importance of antioxidants in the biochemistry of living organisms. The possible mechanisms of action of antioxidants were first explored when it was recognized that a substance with anti-oxidative activity is likely to be one that is itself readily oxidized. Research into how vitamin E prevents the process of lipid peroxidation led to the identification of antioxidants as reducing agents that prevent oxidative reactions, often by scavenging reactive oxygen species before they can damage cells.
Neurotoxin
Tetanus neurotoxin (TeNT) is a compound that functionally reduces inhibitory transmissions in the nervous system resulting in muscular tetany. TeNT is similar to BTX, and is in fact highly similar in structure and origin; both belonging to the same category of clostridial neurotoxins. Like BTX, TeNT inhibits inter-neuron communication by means of vesicular neurotransmitter (NT) release. One notable difference between the two compounds is that while BTX inhibits muscular contractions, TeNT induces them. Though both toxins inhibit vesicle release at neuron synapses, the reason for this different manifestation is that BTX functions mainly in the peripheral nervous system (PNS) while TeNT is largely active in the central nervous system (CNS). This is a result of TeNT migration through motor neurons to the inhibitory neurons of the spinal cord after entering through endocytosis. This results in a loss of function in inhibitory neurons within the CNS resulting in systemic muscular contractions. Similar to the prognosis of a lethal dose of BTX, TeNT leads to paralysis and subsequent suffocation.
Neuromuscular junction
Botulinum toxin (aka botulinum neurotoxin, BoNT, and sold under the trade name Botox) inhibits the release of acetylcholine at the neuromuscular junction by interfering with SNARE proteins. This toxin crosses into the nerve terminal through the process of endocytosis and subsequently interferes with SNARE proteins, which are necessary for ACh release. By doing so, it induces a transient flaccid paralysis and chemical denervation localized to the striated muscle that it has affected. The inhibition of the ACh release does not set in until approximately two weeks after the injection is made. Three months after the inhibition occurs, neuronal activity begins to regain partial function, and six months, complete neuronal function is regained.
Anaerobic infection
Toxin can be neutralized by specific antitoxins, mainly in infections caused by Clostridia (tetanus and botulism). Controlling the environment can be attained by draining the pus, surgical debriding of necrotic tissue, improving blood circulation, alleviating any obstruction and by improving tissue oxygenation. Therapy with hyperbaric oxygen (HBO) may also be useful. The main goal of antimicrobials is in restricting the local and systemic spread of the microorganisms.
Superantigen
To summarize, the T-cells are stimulated and produce excess amounts of cytokine resulting in cytokine-mediated suppression of T-cells and deletion of the activated cells as the body returns to homeostasis. The toxic effects of the microbe and SAg also damage tissue and organ systems, a condition known as Toxic Shock Syndrome.
CcdA/CcdB Type II Toxin-antitoxin system
The Ccd and parD systems are found to be strikingly similar in terms of their structures and actions. The antitoxin protein of each system interacts with its cognate toxin to neutralise the activity of the toxin and in the process the complex of the two becomes an efficient transcription repressor.
Toxin-antitoxin system
Toxins of type I systems are small, hydrophobic proteins that confer toxicity by damaging cell membranes. Few intracellular targets of type I toxins have been identified, possibly due to the difficult nature of analysing proteins that are poisonous to their bacterial hosts.
Ergosterol
Amphotericin B, an antifungal drug, targets ergosterol. It binds physically to ergosterol within the membrane, thus creating a polar pore in fungal membranes. This causes ions (predominantly potassium and protons) and other molecules to leak out, which will kill the cell. Amphotericin B has been replaced by safer agents in most circumstances, but is still used, despite its side effects, for life-threatening fungal or protozoan infections.
Addiction module
Proteic addiction modules use proteins as toxins and antitoxins, as opposed to RNA or other methods. The known proteic addiction modules all have similar shared characteristics, including placement of the antitoxin gene relative to the toxin gene, method of toxin neutralization by the antitoxin, and autoregulation of the addiction module by the antitoxin or toxin:antitoxin complex.
In protein-based addiction modules, the genes encoding the toxin and antitoxin lie adjacent to each other and are continuously expressed under one operon. To ensure survival of the host when the addiction module is present, more antitoxin must be produced than toxin (to counter the shorter lifespan of the antitoxin molecules). Safe ratios of the toxin and antitoxin are maintained at least in part by both this overexpression and by having the antitoxin-encoding gene encoded upstream from the toxin gene, so that the antitoxin is available to immediately neutralize the toxin. This upstream placement of the antitoxin gene is found in all proteic addiction modules.
In addition, the transcription of the whole addiction module is often negatively autoregulated (i.e. the presence of its products decreases its transcriptional rate) by the formation of toxin:antitoxin complexes.
Cellular stress response
Many toxins end up activating similar stress proteins to heat or other stress-induced pathways because it is fairly common for some types of toxins to achieve their effects - at least in part - by denaturing vital cellular proteins. For example, many heavy metals can react with sulfhydryl groups stabilizing proteins, resulting in conformational changes, and other toxins that either directly or indirectly lead to the release of free radicals can generate misfolded proteins.
Tityustoxin
The lung edema induced by TsTX is blocked by phenobarbital. Rabbit anti-TsNTxP antibodies displayed cross-reactivity with the scorpion toxins and showed "in vitro" neutralizing capacity. Thus, this protein emerges as a strong candidate for the production of antiserum to be used in the treatment of scorpion stings. The nontoxic recombinant protein can induce a level of circulating antibodies sufficient to neutralize the toxic effects of Tityus toxins and is a good candidate for use in the production of a new generation of neutralizing polyclonal antibodies for clinical use.
Antifolate
Antifolates are a class of antimetabolite medications that antagonise (that is, block) the actions of folic acid (vitamin B). Folic acid's primary function in the body is as a cofactor to various methyltransferases involved in serine, methionine, thymidine and purine biosynthesis. Consequently, antifolates inhibit cell division, DNA/RNA synthesis and repair and protein synthesis. Some such as proguanil, pyrimethamine and trimethoprim selectively inhibit folate's actions in microbial organisms such as bacteria, protozoa and fungi. The majority of antifolates work by inhibiting dihydrofolate reductase (DHFR).
Botulinum toxin
In 1820, Justinus Kerner, a small-town German medical officer and romantic poet, gave the first complete description of clinical botulism based on extensive clinical observations of so-called “sausage poisoning”. Following experiments on animals and on himself, he concluded that the toxin acts by interrupting signal transmission in the somatic and autonomic motor systems, without affecting sensory signals or mental functions. He observed that the toxin develops under anaerobic conditions, and can be lethal in minute doses. His prescience in suggesting that the toxin might be used therapeutically earned him recognition as the pioneer of modern botulinum toxin therapy.
Exotoxin
They may exert their effect locally or produce systemic effects. Well-known exotoxins include: botulinum toxin produced by "Clostridium botulinum"; "Corynebacterium diphtheriae" toxin, produced during life-threatening symptoms of diphtheria; tetanospasmin produced by Clostridium tetani. The toxic properties of most exotoxins can be inactivated by heat or chemical treatment to produce a toxoid. These retain their antigenic specificity and can be used to produce antitoxins and, in the case of diphtheria and tetanus toxoids, are used as vaccines.
ALECSAT
In order to have efficient eradication of cancer cells, the immune system cells should be able to both populate in the secondary lymphoid organs for a long-lasting effect and target a shared variety of tumor cells as opposed to one, specific cancer cell. In the ALECSAT method, several different cells are activated to accomplish this. Cytotoxic T lymphocytes (CTL) are activated to target the cells that present proteins characteristic of tumor cells Some tumor cells, however, do not present an antigen due to lack of a major histocompatibility complex (MHC) and therefore cannot be recognized by the CTLs. The cells that do not present an antigen are targeted by activated NK cells, leaving little opportunity for any cancer cells to escape. CTLs and NK cells are both effector cells so helper T-cells (T) are also prepared in order to create memory cells for long term resistance toward tumor cells. T helper 1 (TH1) cells, when injected with overexpressed tumor antigens, have been shown to enhance migration of antigen-presenting cells (APCs) into the draining lymph node in mice, further enhancing immune response through activation of CTLs.
Chemotherapy
Antibody-drug conjugates (ADCs) comprise an antibody, drug and a linker between them. The antibody will be targeted at a preferentially expressed protein in the tumour cells (known as a tumor antigen) or on cells that the tumor can utilise, such as blood vessel endothelial cells. They bind to the tumor antigen and are internalised, where the linker releases the drug into the cell. These specially targeted delivery vehicles vary in their stability, selectivity, and choice of target, but, in essence, they all aim to increase the maximum effective dose that can be delivered to the tumor cells. Reduced systemic toxicity means that they can also be used in people who are sicker, and that they can carry new chemotherapeutic agents that would have been far too toxic to deliver via traditional systemic approaches.
TisB-IstR toxin-antitoxin system
The proposed function of this toxin-antitoxin system is to cause growth arrest, rather than cell death, in response to DNA damage, allowing time for repair processes to occur. TisB translation is under LexA control, so it is induced by DNA damage as part of the SOS response. Under normal conditions, very little "tisB" mRNA is synthesised and translation is inhibited, but when DNA damage occurs "tisAB" is strongly induced causing overexpression, which overrides inhibition by depleting the IstR-1 pool.
Antillatoxin
There are three known analogous structures of ATX which have different toxicity: antillatoxin B (8-demethyl-antillatoxin) and DH-ATX (8-demethyl-8,9-dihydro-antillatoxin), and various stereoisomers of antillatoxin A. These various structures have been found to be less toxic than antillatoxin A. Synthetic versions of antillatoxin have been produced with conformational variations of the lipophilic side chain. All of these structures drastically changed the toxins activity. Structures where the C7-C8=C9 bond angle was closer to 180 showed lower levels of toxicity in cell cultures. Structures that added a bulky side group to the C5 position also showed dramatic decreases in toxicity, including loss of activity.
CcdA/CcdB Type II Toxin-antitoxin system
The ccd system (control of cell death) of the F plasmid encodes two proteins, the CcdB protein (101 amino acids; toxin) and the CcdA antidote (72 amino acids). The antidote prevents CcdB toxicity by forming a tight CcdA–CcdB complex.
Antioxidant
Antioxidants are compounds that inhibit oxidation. Oxidation is a chemical reaction that can produce free radicals, thereby leading to chain reactions that may damage the cells of organisms. Antioxidants such as thiols or ascorbic acid (vitamin C) terminate these chain reactions. To balance the oxidative state, plants and animals maintain complex systems of overlapping antioxidants, such as glutathione and enzymes (e.g., catalase and superoxide dismutase), produced internally, or the dietary antioxidants vitamin C, and vitamin E.
Microbial toxin
Microbial toxins are toxins produced by micro-organisms, including bacteria and fungi. Microbial toxins promote infection and disease by directly damaging host tissues and by disabling the immune system. Some bacterial toxins, such as "Botulinum" neurotoxins, are the most potent natural toxins known. However, microbial toxins also have important uses in medical science and research. Potential applications of toxin research include combating microbial virulence, the development of novel anticancer drugs and other medicines, and the use of toxins as tools in neurobiology and cellular biology.
Antimetabolite
Antimetabolites may also be antibiotics, such as sulfanilamide drugs, which inhibit dihydrofolate synthesis in bacteria by competing with para-aminobenzoic acid (PABA). PABA is needed in enzymatic reactions that produce folic acid, which acts as a coenzyme in the synthesis of purines and pyrimidines, the building-blocks of DNA. Mammals do not synthesize their own folic acid so they are unaffected by PABA inhibitors, which selectively kill bacteria. Sulfanilamide drugs are not like the antibiotics used to treat infections. Instead, they work by changing the DNA inside cancer cells to keep them from growing and multiplying. Antitumor antibiotics are a class of antimetabolite drugs that are cell cycle nonspecific. They act by binding with DNA molecules and preventing RNA (ribonucleic acid) synthesis, a key step in the creation of proteins, which are necessary for cancer cell survival.
Toxin-antitoxin system
Type IV toxin-antitoxin systems are similar to type II systems, because they consist of two proteins. Unlike type II systems, the antitoxin in type IV toxin-antitoxin systems counteracts the activity of the toxin, and the two proteins do not directly interact.
Toxin-antitoxin system
"mazEF", a toxin-antitoxin locus found in "E. coli" and other bacteria, was proposed to induce programmed cell death in response to starvation, specifically a lack of amino acids. This would release the cell's contents for absorption by neighbouring cells, potentially preventing the death of close relatives, and thereby increasing the inclusive fitness of the cell that perished. This would be an example of altruism and how bacterial colonies could resemble multicellular organisms. However, the ""mazEF"-mediated PCD" has largely been refuted by several studies.
Toxin-antitoxin system
Chromosomal toxin-antitoxin systems also exist, some of which are thought to perform cell functions such as responding to stresses, causing cell cycle arrest and bringing about programmed cell death. In evolutionary terms, toxin-antitoxin systems can be considered selfish DNA in that the purpose of the systems are to replicate, regardless of whether they benefit the host organism or not. Some have proposed adaptive theories to explain the evolution of toxin-antitoxin systems; for example, chromosomal toxin-antitoxin systems could have evolved to prevent the inheritance of large deletions of the host genome. Toxin-antitoxin systems have several biotechnological applications, such as a maintaining plasmids in cell lines, targets for antibiotics, and as positive selection vectors.
Chemoreceptor trigger zone
Antiemetic medications often target the CTZ to completely inhibit or greatly reduce vomiting. Most of these work by not allowing certain blood-borne drugs (usually pain killers or stimulants) to bind to their respective receptors located in the CTZ. The antiemetic medications can block the binding site on a chemoreceptor in the CTZ, so that the emetic agent cannot bind to it to cause its emetic effects. Another way that antiemetic medications can work is by binding to a chemoreceptor in the CTZ, but instead of initiate vomiting, the medication can cause the receptors to send signals to the other parts of the vomiting center that inhibit emesis. Also, some anti-emetic medications work by lowering the amount of dopamine levels in the brain, which in turn effects how much dopamine comes in contact with dopamine receptors in the CTZ. Other antiemetic medications work similarly by lowering a different substance in the brain that is known to interact with chemoreceptors in the CTZ that cause emesis.
Botulism
"Clostridium botulinum" is an anaerobic, Gram positive, spore-forming rod. Botulinum toxin is one of the most powerful known toxins: about one microgram is lethal to humans when inhaled. It acts by blocking nerve function (neuromuscular blockade) through inhibition of the excitatory neurotransmitter acetylcholine's release from the presynaptic membrane of neuromuscular junctions in the somatic nervous system. This causes paralysis. Advanced botulism can cause respiratory failure by paralysing the muscles of the chest; this can progress to respiratory arrest. Furthermore, acetylcholine release from the presynaptic membranes of muscarinic nerve synapses is blocked. This can lead to a variety of autonomic signs and symptoms described above.
Pore-forming toxin
ADP-ribosylation is a common enzymatic method used by different bacterial toxins from various species. Toxins such as "C. perfringens" iota toxin and "C. botulinum" C2 toxin, attach a ribosyl-ADP moiety to surface arginine residue 177 of G-actin. This prevents G-actin assembling to form F-actin, and, thus, the cytoskeleton breaks down, resulting in cell death. Insecticidal members of the ADP-ribosyltransferase family of toxins include the Mtx1 toxin of "Lysinibacillus sphaericus" and the Vip1/Vip2 toxin of "Bacillus thuringiensis" and some members of the toxin complex (Tc) toxins from gram negative bacteria such as "Photorhabdus" and "Xenorhabdus" species. The beta sheet-rich regions of the Mtx1 protein are lectin-like sequences that may be involved in glycolipid interactions.
Clostridium difficile toxin B
By adding antimicrobial, e.g. clindamycin, into the culture growth medium, studies have shown that the cytotoxic activity in "C. difficile" cultures increases by 4–8 fold. Moreover, knowing the role of antibiotics on the causes of PMC, many earlier studies focused on the effects of antimicrobials production of toxins. As a result, studies were able to conclude that the subinhibitory nature of vancomycin and penicillin levels were increasing the toxin production in cultures of "C. difficile". The amounts of toxin production were correlated with the usage of growth medium for the organisms. Another study illustrated that the high levels of toxin production of TcdB were observed in complex mediums such as brain and heart infusion broth. High levels of toxins were produced with isolation of highly virulent. Conversely, low levels of toxins were produced with isolation of weakly virulent. Thus, it shows that the productions of toxins were co-regulated. Although the mechanism behind the environment's involvement in modulating the signals expressing the toxins is not understood, in vitro studies have shown that expression of toxin is strengthened by catabolite repression and stress, e.g. antibiotics. Another study has shown that limiting biotin in well-characterized medium increases the production of TcdB by 64-fold and TcdA by 35-fold. This was done with "C. difficile" and doses of biotin as small as 0.05nM. Several other early studies have argued against the theory that the production of toxin has anything to deal with stress or catabolite repression of either toxin TcdA or TcdB. Also, many studies say the main reason for the differences among other studies is due to toxin production not occurring with all isolates of "C. difficile".
Exotoxin
As exotoxins are highly potent, there has been development in their application to cancer treatment. Cancer cells can be eliminated without destroying normal cells like in chemotherapy or radiation by attaching an antibody or receptor ligand to the exotoxin, creating a recombinant toxin that is targeted to certain cells. The cancer cell is killed once the toxin is internalized; for example, Pseudomonas exotoxin disrupts protein synthesis after cellular uptake. Multiple versions of recombinant exotoxin A, secreted by "Pseudomonas aeruginosa", have entered clinical trials against tumor growth but have yet to be approved by Food and Drug Administration. A recombinant diphtheria exotoxin has been approved by the FDA for treatment of cutaneous T-cell lymphoma, an immune system cancer. Further testing to improve clinical efficacy of treatment using recombinant exotoxins continues.
Dendrotoxin
A single dendrotoxin molecule associates reversibly with a potassium channel in order to exert its inhibitory effect. It is proposed that this interaction is mediated by electrostatic interactions between the positively charged amino acid residues in the cationic domain of dendrotoxin and the negatively charged residues in the ion channel pore. Potassium channels, similar to other cation-selective channels, are believed to have a cloud of negative charges that precede the opening to the channel pore that help conduct potassium ions through the permeation pathway. It is generally believed (though not proven) that a dendrotoxin molecules bind to anionic sites near the extracellular surface of the channel and physically occlude the pore, thereby preventing ion conductance. However, Imredy and MacKinnon have proposed that delta-dendrotoxin may have an off-center binding site on their target proteins, and may inhibit the channel by altering the structure of the channel, rather than physically blocking the pore.
Heptavalent botulism antitoxin
"HBAT" is derived from "despeciated" equine IgG antibodies, which have had the Fc portion cleaved off, leaving the F(ab') portions. This process renders it less efficacious at neutralizing toxin than the other product trivalent botulinum antitoxin (TBAT) available from local health departments (via the CDC) for treatment of wound and foodborne botulism. TBAT (effective against types A, B, and E) is derived from equine sources utilizing whole antibodies (Fab & Fc portions). But only "HBAT" is considered effective against all known strains of botulism (A, B, C, D, E, F, and G). These antitoxins neutralize only circulating toxin in patients with symptoms of botulism that are continuing to progress; they have no effect on toxin already bound to the nerve terminals. (This is not, however, considered a reason to withhold the product from any patient, even if treatment has been delayed.)
Enterotoxin
All of these toxins share a similar two-domain fold (N and C-terminal domains) with a long alpha-helix in the middle of the molecule, a characteristic beta-barrel known as the "oligosaccharide/oligonucleotide fold" at the N-terminal domain and a beta-grasp motif at the C-terminal domain. Examples include staphylococcal enterotoxin B. Each superantigen possesses slightly different binding mode(s) when it interacts with MHC class II molecules or the T-cell receptor.
Anticarcinogen
In theory, anticarcinogens may act via different mechanisms including enhancement of natural defences against cancer, deactivation of carcinogens, and blocking the mechanisms by which carcinogens act (such as free radical damage to DNA). Confirmation that a substance possesses anticarcinogenic activity requires extensive "in vitro", "in vivo", and clinical investigation. Health claims for anticarcinogens are regulated by various national and international organizations like the US Food and Drug Administration (FDA) and European Food Safety Authority (EFSA).
Toxicodynamics
Certain toxicants act as endocrine disruptors by interacting with the androgen receptor. DDE is one example of a chemical that acts via this mechanism. DDE is a metabolite of DDT that is widespread in the environment. Although production of DDT has been banned in the Western world, this chemical is extremely persistent and is still commonly found in the environment along with its metabolite DDE. DDE is an antiandrogen, which means it alters the expression of specific androgen-regulated genes, and is an androgen receptor (AR)-mediated mechanism. DDE is a lipophilic compound which diffuses into the cell and binds to the AR. Through binding, the receptor is inactivated and cannot bind to the androgen response element on DNA. This inhibits the transcription of androgen-responsive genes which can have serious consequences for exposed wildlife. In 1980, there was a spill in Lake Apopka, Florida which released the pesticide dicofol and DDT along with its metabolites. The neonatal and juvenile alligators present in this lake have been extensively studied and observed to have altered plasma hormone concentrations, decreased clutch viability, increased juvenile mortality, and morphological abnormalities in the testis and ovary.
Anuroctoxin
The α-KTx inhibition of the potassium channels is mediated by a simple bimolecular plugging mechanism: the extracellular pore, which has a specific receptor site, is occluded by a single toxin molecule binding to it. Whether this block is voltage dependent, which is common in scorpion toxins remains to be seen. This pore block is however fully reversible, which implies that it is not a potent neurotoxin.
Anthrax toxin
The mechanism of anthrax toxin action is the result of the molecular structures of the three toxin proteins in combination with biomolecules of the host cell. The molecular interactions are apparent upon performing a detailed analysis of the structures of PA, EF, LF, and the cellular receptors (ANTXR1 and ANTXR2). Structures for the toxin molecules (Figs. 3–5), the receptor, and for the complexes of the molecules all provided insight on the synergistic actions of these proteins. Analyses on binding sites and conformational changes augmented the structural studies, elucidating the functions of each domain of PA, LF, and EF, as briefly outlined in Table 1.
Neuromuscular junction
Postsynaptic neurotoxins, otherwise known as α-neurotoxins, act oppositely to the presynaptic neurotoxins by binding to the postsynaptic acetylcholine receptors. This prevents interaction between the acetylcholine released by the presynaptic terminal and the receptors on the postsynaptic cell. In effect, the opening of sodium channels associated with these acetylcholine receptors is prohibited, resulting in a neuromuscular blockade, similar to the effects seen due to presynaptic neurotoxins. This causes paralysis in the muscles involved in the affected junctions. Unlike presynaptic neurotoxins, postsynaptic toxins are more easily affected by anti-venoms, which accelerate the dissociation of the toxin from the receptors, ultimately causing a reversal of paralysis. These neurotoxins experimentally and qualitatively aid in the study of acetylcholine receptor density and turnover, as well as in studies observing the direction of antibodies toward the affected acetylcholine receptors in patients diagnosed with myasthenia gravis.
Cangitoxin
Sea anemone toxins act on voltage-gated sodium channels (Na1.1, Na1.2, Na1.4, Na1.5, Na1.6, Na1.7) and depending on their affinity to a specific isoform, they mainly act on cardiac or neuronal voltage-gated sodium channels. Sea anemone toxins act at the receptor site 3. On the basis of its sequence homology, cangitoxin most likely acts on the same receptor site of the previously mentioned sodium channels. Neurotoxin receptor site 3 is localized on the extracellular side of the IVS4 transmembrane segment. The S4 segments of sodium channels move outward when the membrane depolarizes.
Toxin-antitoxin system
Another example application involves both the CcdB toxin and CcdA antitoxin. CcdB is found in recombinant bacterial genomes and an inactivated version of CcdA is inserted into a linearised plasmid vector. A short extra sequence is added to the gene of interest that activates the antitoxin when the insertion occurs. This method ensures orientation-specific gene insertion.
Loxoscelism
Anti-venoms are commercially prepared antibodies to toxins in animal bites. They are specific for each bite. There are several anti-venoms commercially available in Brazil, which have been shown to be effective in controlling the spread of necrosis in rabbits. When administered immediately, they can almost entirely neutralize any ill effects. If too much time is allowed to pass, the treatment becomes ineffective. Most victims do not seek medical attention within the first twelve hours of being bitten, and these anti-venoms are largely ineffective after this point. Because of this, anti-venoms are not being developed more widely. They have, however, been proven to be very effective if administered in a timely manner and could be utilized in Brazil as a legitimate technique.
Antithrombotic
An antithrombotic agent is heprin a drug that reduces the formation of blood clots (thrombi). Antithrombotics can be used therapeutically for prevention (primary prevention, secondary prevention) or treatment of a dangerous blood clot (acute thrombus). In the U.S., the American College of Chest Physicians publishes clinical guidelines for clinicians for the use of these drugs to treat and prevent a variety of diseases.
Transgender hormone therapy (male-to-female)
Antiandrogens are medications that prevent the effects of androgens in the body. Androgens, such as testosterone and dihydrotestosterone (DHT), are the major sex hormones in individuals with testes, and are responsible for the development and maintenance of masculine secondary sex characteristics, such as a deep voice, broad shoulders, and a masculine pattern of hair, muscle, and fat distribution. In addition, androgens stimulate sex drive and the frequency of spontaneous erections and are responsible for acne, body odor, and androgen-dependent scalp hair loss. They also have functional antiestrogenic effects in the breasts and oppose estrogen-mediated breast development, even at low levels. Androgens act by binding to and activating the androgen receptor, their biological target in the body. Antiandrogens work by blocking androgens from binding to the androgen receptor and/or by inhibiting or suppressing the production of androgens.
Anti-protist
Anti-protist or antiprotistal refers to an anti-parasitic and anti-infective agent which is active against protists. Unfortunately due to the long ingrained usage of the term antiprotozoal, the two terms are confused, when in fact protists are a supercategory. Therefore, there are protists that are not protozoans.
Enzyme inhibitor
Proteins can also be natural poisons or antinutrients, such as the trypsin inhibitors (discussed above) that are found in some legumes, as shown in the figure above. A less common class of toxins are toxic enzymes: these act as irreversible inhibitors of their target enzymes and work by chemically modifying their substrate enzymes. An example is ricin, an extremely potent protein toxin found in castor oil beans. This enzyme is a glycosidase that inactivates ribosomes. Since ricin is a catalytic irreversible inhibitor, this allows just a single molecule of ricin to kill a cell.
Superantigen
One such effect is emesis. This effect is felt in cases of food poisoning, when SAg-producing bacteria release the toxin, which is highly resistant to heat. There is a distinct region of the molecule that is active in inducing gastrointestinal toxicity. This activity is also highly potent, and quantities as small as 20-35 μg of SAg are able to induce vomiting.
Bactridines
Bactridines are a group of six antibacterial peptides from the venom of the "Tityus" "discrepans" scorpion. They exclusively target sodium channels. Bactridines are unique in that this scorpion toxin acts on sodium channels of both bacteria and eukaryotes.
The name bactridine is derived from the fact that these toxins not only help scorpions to kill their preys but also protect their bodies from harmful pathogens by inhibiting bacteria growth. In captivity, scorpions spray the toxin over their own bodies which suggest that they use the toxin for protection or cleansing.
Pore-forming toxin
Some binary toxins are composed of an enzymatic component and a component that is involved in membrane interactions and entry of the enzymatic component into the cell. 
The membrane interacting component may have structural domains that are rich in beta sheets. Binary toxins, such as anthrax lethal and edema toxins (Main article: Anthrax toxin), "C. perfringens iota" toxin and "C. difficile" cyto-lethal toxins consist of two components (hence "binary"):In these enzymatic binary toxins, the B component facilitates the entry of the enzymatic 'payload' (A subunit) into the target cell, by forming homooligomeric pores, as shown above for βPFTs. The A component then enters the cytosol and inhibits normal cell functions by one of the following means:
Diphtheria
Antibiotics have not been demonstrated to affect healing of local infection in diphtheria patients treated with antitoxin. Antibiotics are used in patients or carriers to eradicate "C. diphtheriae" and prevent its transmission to others. The Centers for Disease Control and Prevention recommends either:In cases that progress beyond a throat infection, diphtheria toxin spreads through the blood and can lead to potentially life-threatening complications that affect other organs, such as the heart and kidneys. Damage to the heart caused by the toxin affects the heart's ability to pump blood or the kidneys' ability to clear wastes. It can also cause nerve damage, eventually leading to paralysis. About 40% to 50% of those left untreated can die.
Enzyme inhibitor
Animals and plants have evolved to synthesise a vast array of poisonous products including secondary metabolites, peptides and proteins that can act as inhibitors. Natural toxins are usually small organic molecules and are so diverse that there are probably natural inhibitors for most metabolic processes. The metabolic processes targeted by natural poisons encompass more than enzymes in metabolic pathways and can also include the inhibition of receptor, channel and structural protein functions in a cell. For example, paclitaxel (taxol), an organic molecule found in the Pacific yew tree, binds tightly to tubulin dimers and inhibits their assembly into microtubules in the cytoskeleton.
Botulinum toxin
Two preparations of botulinum antitoxins are available for treatment of botulism. Trivalent (A,B,E) botulinum antitoxin is derived from equine sources using whole antibodies. The second antitoxin is Heptavalent (A,B,C,D,E,F,G) botulinum antitoxin, which is derived from equine antibodies which have been altered to make them less immunogenic. This antitoxin is effective against all known strains of botulism.
BotIT6
Bot1T6 is a positively charged basic structure. Basic toxins are usually more potent than acidic ones. In addition, within the Buthidae neurotoxin family toxins, a higher total positive charge leads to a more toxic neuropeptide . These characteristics contribute in making Bot1T6 a very effective insect toxin. For cockroaches for instance, the LD50 was 10 ng/100 mg. Amongst other things this toxin leads to different forms of paralysis and uncoordinated motion. Although paralysis can sometimes be reversed but death can also occur without any previous warning symptoms. These effects occur only in insects.
Stromatoxin
The effect of the toxin strongly varies with the tissue in which the channels are expressed. Stromatoxin for example prohibits apoptosis in enterocytes and enhances myogenic constriction in (rat) cerebral arteries .
Pore-forming toxin
Bacteria may invest much time and energy in making these toxins: CPE can account for up to 15% of the dry mass of "C. perfringens" at the time of sporulation. The purpose of toxins is thought to be one of the following:
Chemotherapy
Anti-metabolites are a group of molecules that impede DNA and RNA synthesis. Many of them have a similar structure to the building blocks of DNA and RNA. The building blocks are nucleotides; a molecule comprising a nucleobase, a sugar and a phosphate group. The nucleobases are divided into purines (guanine and adenine) and pyrimidines (cytosine, thymine and uracil). Anti-metabolites resemble either nucleobases or nucleosides (a nucleotide without the phosphate group), but have altered chemical groups. These drugs exert their effect by either blocking the enzymes required for DNA synthesis or becoming incorporated into DNA or RNA. By inhibiting the enzymes involved in DNA synthesis, they prevent mitosis because the DNA cannot duplicate itself. Also, after misincorporation of the molecules into DNA, DNA damage can occur and programmed cell death (apoptosis) is induced. Unlike alkylating agents, anti-metabolites are cell cycle dependent. This means that they only work during a specific part of the cell cycle, in this case S-phase (the DNA synthesis phase). For this reason, at a certain dose, the effect plateaus and proportionally no more cell death occurs with increased doses. Subtypes of the anti-metabolites are the anti-folates, fluoropyrimidines, deoxynucleoside analogues and thiopurines.
Antidote
Some other toxins have no known antidote. For example, the poison aconitine – a highly poisonous alkaloid derived from various aconite species – has no antidote, and as a result is often fatal if it enters the human body in sufficient quantities.
SymE-SymR toxin-antitoxin system
The SymE-SymR toxin-antitoxin system consists of a small hydrophobic toxin named SymE and a non-coding RNA called SymR which inhibits its translation. It is a type I toxin-antitoxin system, and is under regulation by the antitoxin, SymR.
Bacillus subtilis type I antitoxin SR6
SR6 is a 100 nucleotide long antisense RNA antitoxin that overlaps 2 toxins: 3' end of "yonT" and "yoyJ" at its 5'end. In type I toxin-antitoxin (TA) systems the antitoxin is a small RNA that neutralizes a toxin protein. Several type I TA systems have been described in "B. subtilis". "YonT"/SR6 system is located on the SPβ prophage of the "B. subtilis" chromosome and it was shown to be multi-stress responsive. SR6 acts by promoting "yonT" mRNA degradation. It may regulate the second toxin, "yoyJ" by a different mechanism.
Exotoxin
Exotoxins are susceptible to antibodies produced by the immune system, but many exotoxins are so toxic that they may be fatal to the host before the immune system has a chance to mount defenses against them. For this reason antitoxin, anti-serum containing antibodies, is injected to provide passive immunity.
Dinotoxin
Some dinotoxins are useful in pain management. These toxins may have potential therapeutic effects along with other medical applications, including antiviral, antibacterial, and antioxidant activity. Free-radical scavenging, inflammation control, and tumor destruction are also applications of dinotoxins. They can act as anticoagulants, biolubricants, and can prevent pathogenic microorganisms from binding to cell membranes with an anti-adhesive property.
Antitoxin
Antitoxins to diphtheria and tetanus toxins were produced by Emil Adolf von Behring and his colleagues from 1890 onwards. The use of diphtheria antitoxin for the treatment of diphtheria was regarded by "The Lancet" as the "most important advance of the [19th] Century in the medical treatment of acute infectious disease".
Antillatoxin
Antillatoxin activates voltage-gated sodium channels, thus increasing sodium influx into the cell. It is hypothesized that ATX creates the increase in sodium influx by altering the voltage-gating properties of the channel. The toxin might change the voltage dependence of inactivation or augment the rate of recovery from inactivation. The effect is concentration dependent, with similar potency for the rNav1.2, rNav1.4 and rNav1.5 α-subunit types of sodium channels.
Tetanus
The tetanus toxin initially binds to peripheral nerve terminals. It is transported within the axon and across synaptic junctions until it reaches the central nervous system. There it becomes rapidly fixed to gangliosides at the presynaptic inhibitory motor nerve endings, and is taken up into the axon by endocytosis. The effect of the toxin is to block the release of inhibitory neurotransmitters glycine and gamma-aminobutyric acid (GABA) across the synaptic cleft, which is required to check the nervous impulse. If nervous impulses cannot be checked by normal inhibitory mechanisms, the generalized muscular spasms characteristic of tetanus are produced. The toxin appears to act by selective cleavage of a protein component of synaptic vesicles, synaptobrevin II, and this prevents the release of neurotransmitters by the cells.
Chemical defense
Bacteria of the genera "Chromobacterium", "Janthinobacterium", and "Pseudoalteromonas" produce a toxic secondary metabolite, violacein, to deter protozoan predation. Violacein is released when bacteria are consumed, killing the protozoan. Another bacteria, "Pseudomonas aeruginosa", aggregates into quorum sensing biofilms which may aid the coordinated release of toxins to protect against predation by protozoans. Flagellates were allowed to grow and were present in a biofilm of "P. aeruginosa" grown for three days, but no flagellates were detected after seven days. This suggests that concentrated and coordinated release of extracellular toxins by biofilms has a greater effect than unicellular excretions. Bacterial growth is inhibited not only by bacterial toxins, but also by secondary metabolites produced by fungi as well. The most well-known of these, first discovered and published by Alexander Fleming in 1929, described the antibacterial properties of a "mould juice" isolated from "Penicillium notatum". He named the substance penicillin, and it became the world's first broad-spectrum antibiotic. Many fungi are either pathogenic saprophytic, or live within plants without harming them as endophytes, and many of these have been documented to produce chemicals with antagonistic effects against a variety of organisms, including fungi, bacteria, and protozoa. Studies of coprophilous fungi have found antifungal agents which reduce the fitness of competing fungi. In addition, sclerotia of "Aspergillus flavus" contained a number of previously unknown aflavinines which were much more effective at reducing predation by the fungivorous beetle, "Carpophilus hemipterus", than aflatoxins which "A. flavus" also produced and it has been hypothesized that ergot alkaloids, mycotoxins produced by "Claviceps purpurea", may have evolved to discourage herbivory of the host plant.
Toxoid
A toxoid is an inactivated toxin (usually an exotoxin) whose toxicity has been suppressed either by chemical (formalin) or heat treatment, while other properties, typically immunogenicity, are maintained. Toxins are secreted by bacteria, whereas toxoids are altered form of toxins; toxoids are "not" secreted by bacteria. Thus, when used during vaccination, an immune response is mounted and immunological memory is formed against the molecular markers of the toxoid without resulting in toxin-induced illness. In international medical literature the preparation also is known as anatoxin or anatoxine. There are toxoids for prevention of diphtheria, tetanus and botulism.
Neurotoxin
As neurotoxins are compounds which adversely affect the nervous system, a number of mechanisms through which they function are through the inhibition of neuron cellular processes. These inhibited processes can range from membrane depolarization mechanisms to inter-neuron communication. By inhibiting the ability for neurons to perform their expected intracellular functions, or pass a signal to a neighboring cell, neurotoxins can induce systemic nervous system arrest as in the case of botulinum toxin, or even nervous tissue death. The time required for the onset of symptoms upon neurotoxin exposure can vary between different toxins, being on the order of hours for botulinum toxin and years for lead.
Enterotoxin type B
All of these toxins share a similar two-domain fold (N and C-terminal domains) with a long alpha-helix in the middle of the molecule, a characteristic beta-barrel known as the "oligosaccharide/oligonucleotide fold" at the N-terminal domain and a beta-grasp motif at the C-terminal domain. Each superantigen possesses slightly different binding mode(s) when it interacts with MHC class II molecules or the T-cell receptor.
Heptavalent botulism antitoxin
The Botulism Antitoxin Heptavalent (A, B, C, D, E, F, G) - (Equine) (BAT) – BAT, made by Emergent BioSolutions Canada Inc. (formerly Cangene Corporation), – is a licensed, commercially available botulism anti-toxin that effectively neutralizes all seven known botulinum nerve toxin serotypes (types A, B, C, D, E, F and G). It is indicated for sporadic cases of life-threatening botulism and is also stockpiled for the eventuality of botulinum nerve toxins being used in a future bioterrorist attack.
LdrD-RdlD toxin-antitoxin system
The precise mechanism by which RdlD inhibits LdrD is unknown, however it has been shown that RdlD seems to regulate LdrD expression at the post-transcriptional level. The RdlD antisense RNA does not overlap with the translational initiation region of "ldrD", as is common with Type 1 toxin-antitoxin systems.
Antivirulence
Approved antivirulence drugs
Early examples of the antivirulence approach include mainly the inactivation of bacterial toxins with anti-toxin antibodies administered to post-exposure patients (serological therapy that induces artificially acquired passive immunization). Since inactivation of toxin during infection has proven to be an effective way to prevent or alleviate the symptoms of acute disease, significant progress has been made in the development of novel anti-toxic monoclonal antibodies. Therefore, in October 2016 the US Food and Drug Administration (FDA) and in July 2018 the Italian Drug Agency (AIFA) approved the therapeutic use of a monoclonal antibody called bezlotoxumab (Zinplava) as a treatment aimed at reducing the recurrence of "Clostridium difficile" infection (CDI)in patients at high risk of recurrence.
Botulism
In adults, a trivalent antitoxin containing antibodies raised against botulinum toxin types A, B, and E is used most commonly, however a heptavalent botulism antitoxin has also been developed and was approved by the U.S. FDA in 2013. In infants, horse-derived antitoxin is sometimes avoided for fear of infants developing serum sickness or lasting hypersensitivity to horse-derived proteins. To avoid this, a human-derived antitoxin has been developed and approved by the U.S. FDA in 2003 for the treatment of infant botulism. This human-derived antitoxin has been shown to be both safe and effective for the treatment of infant botulism. However, the danger of equine-derived antitoxin to infants has not been clearly established, and one study showed the equine-derived antitoxin to be both safe and effective for the treatment of infant botulism.
Action potential
Several neurotoxins, both natural and synthetic, are designed to block the action potential. Tetrodotoxin from the pufferfish and saxitoxin from the "Gonyaulax" (the dinoflagellate genus responsible for "red tides") block action potentials by inhibiting the voltage-sensitive sodium channel; similarly, dendrotoxin from the black mamba snake inhibits the voltage-sensitive potassium channel. Such inhibitors of ion channels serve an important research purpose, by allowing scientists to "turn off" specific channels at will, thus isolating the other channels' contributions; they can also be useful in purifying ion channels by affinity chromatography or in assaying their concentration. However, such inhibitors also make effective neurotoxins, and have been considered for use as chemical weapons. Neurotoxins aimed at the ion channels of insects have been effective insecticides; one example is the synthetic permethrin, which prolongs the activation of the sodium channels involved in action potentials. The ion channels of insects are sufficiently different from their human counterparts that there are few side effects in humans.
Toxin-antitoxin system
A toxin-antitoxin system is a set of two or more closely linked genes that together encode both a "toxin" protein and a corresponding "antitoxin". When these systems are contained on plasmids – transferable genetic elements – they ensure that only the daughter cells that inherit the plasmid survive after cell division. If the plasmid is absent in a daughter cell, the unstable antitoxin is degraded and the stable toxic protein kills the new cell; this is known as 'post-segregational killing' (PSK). Toxin-antitoxin systems are widely distributed in prokaryotes, and organisms often have them in multiple copies.
Tabtoxin
Tabtoxin resistance protein (TTR) is an enzyme that catalyzes the acetylation of tabtoxin rendering tabtoxin-producing pathogens tolerant to their own phytotoxins. According to the structure based detoxification mechanism of TTR, three site-directed mutants Y141F, D130N and Y141F-D130N were constructed and overexpressed in E. coli. The products were then purified and their properties were analyzed by CD and DLS. The crystal structure of TTR complexed with its natural cofactor, acetyl coenzyme A (AcCoA), to 1.55 Å resolution. The binary complex forms a characteristic “V” shape for substrate binding and contains the four motifs conserved in the GCN5-related N-acetyltransferase (GNAT) superfamily, which also includes the histone acetyltransferases (HATs). There are reports that TTR possesses HAT activity and suggest an evolutionary relationship between TTR and other GNAT members. The dipeptide toxin contains tabtoxinine-β-lactam (TβL) linked by a peptide bond to threonine produced, the chlorosis-inducing activity occurs only after hydrolysis of the peptide bond by aminopeptidases of plant or bacterial origin. Cleavage of the peptide bond in tabtoxin releases TβL, the toxic moiety. TβL is located at the N terminus, and Thr is at the C terminus, resulting in TβL-Thr. TβL-Thr is hydrolyzed, and the resulting TβL irreversibly inhibits glutamine synthetase, causing characteristic chlorosis in plants. TβL is spontaneously isomerized to tabtoxinine-δ-lactam (TδL), and TblF did not recognize TδL as a substrate, yielding no TδL-Thr. Some characteristics were also provided by them, but only from the perspective of tabtoxin biosynthesis. βL-Thr is observed, but Thr-TβL, whose sequence is the reverse of that of tabtoxin, is not. The effects of carbon, nitrogen sources and amino acids on growth and tabtoxin production by pv. tabaci, were examined by varying the components of a defined basal medium, which contained the following nutrients per liter: sucrose (10 g), KNO3 (5 g), MgSO(4).7H2O (0.2 g), CaCl(2).2H2O (0.11 g), FeSO(4).7H2O (20 mg), NaH2PO(4).2H2O (0.9 g) and H2PO(4).3HO (1 g). Both growth and quantity of tabtoxin synthesized were significantly affected by carbon source, nitrogen source and amino acid supplements. Sorbitol, xylose and sucrose proved to be the best carbon sources for tabtoxin production. Specific toxin production was very low using glucose as a single carbohydrate source, although bacterial growth was well supported by glucose. Amount and type of nitrogen sources (NH4Cl or KNO3) affected the growth of pv. tabaci and quantities of tabtoxin produced. Nitrate is the best of these two forms of nitrogen for production of tabtoxin.
Gonyautoxin
Gonyautoxins can be used as treatment against acute or chronic anal fissures. The toxins help the muscle to relax and hence kill the pain. In a study, the bleedings of the poisoned patients stopped within 48 hours. This is thanks to a temporary paralysis at the injection-area, which appears to last for over one week.
Cross-reactivity
An adaptive immune response is specific to the antigen that stimulated it (called the immunogen). However, many naturally occurring apparent antigens are actually a mixture of macromolecules (for example, from pathogens, toxins, proteins, or pollen) comprising several epitopes. Contact with a complex antigen such as a virus will stimulate multiple immune responses to the virus' different macromolecules as well as the individual epitopes of each macromolecule. For example, the tetanus toxin is a single protein macromolecular antigen but will stimulate many immune responses due to the tertiary structure of the protein yielding many different epitopes. The toxin that creates the immune response will have an epitope on it that stimulates the response. Denaturing the protein may 'disarm' its function but allow the immune system to have an immune response thus creating an immunity without harming the patient.
Toxin
Toxins can be small molecules, peptides, or proteins that are capable of causing disease on contact with or absorption by body tissues interacting with biological macromolecules such as enzymes or cellular receptors. Toxins vary greatly in their toxicity, ranging from usually minor (such as a bee sting) to almost immediately deadly (such as botulinum toxin).
Toxyn
Toxyn had the ability to analyze a person's biochemistry, through physical touch, and synthesize and secrete the whole spectrum of poisons, including their antidotes. She could produce both beneficial and harmful biochemical agents that affected both living and inanimate matter, although she needed skin-to-skin contact to produce a species specific toxin. Toxyn often kissed her opponents in battle, thus ensuring the effectiveness of her poisons, often paralyzing or instantly killing her adversaries. As a by-product of her exposure to the Morituri program, she also had enhanced strength and resilience. Like all other team members, she also wore special boots which enabled her to fly.
Taurolidine
Taurolidine demonstrates some anti-tumor properties, with positive results seen in early-stage clinical investigations using the drug to treat gastrointestinal malignancies and tumors of the central nervous system. More recently, it has been found to exert antineoplastic activity. Taurolidine induces cancer cell death through a variety of mechanisms. Even now, all the antineoplastic pathways it employs are not completely elucidated. It has been shown to enhance apoptosis, inhibit angiogenesis, reduce tumor adherence, downregulate pro-inflammatory cytokine release, and stimulate anticancer immune regulation following surgical trauma. Apoptosis is activated through both a mitochondrial cytochrome-c-dependent mechanism and an extrinsic direct pathway. A lot of in vitro and animal data support taurolidine's tumoricidal action. Taurolidine has been used as an antimicrobial agent in the clinical setting since the 1970s and thus far appears nontoxic. The nontoxic nature of taurolidine makes it a favorable option compared with current chemotherapeutic regimens. Few published clinical studies exist evaluating the role of taurolidine as a chemotherapeutic agent. The literature lacks a gold-standard level 1 randomized clinical trial to evaluate taurolidine's potential antineoplastic benefits. However, these trials are currently underway. Such randomized control studies are vital to clarify the role of taurolidine in modern cancer treatment.
Antibody-drug conjugate
In developing antibody-drug conjugates, an anticancer drug is coupled to an antibody that specifically targets a certain tumor marker (e.g. a protein that, ideally, is only to be found in or on tumor cells). Antibodies track these proteins down in the body and attach themselves to the surface of cancer cells. The biochemical reaction between the antibody and the target protein (antigen) triggers a signal in the tumor cell, which then absorbs or internalizes the antibody together with the cytotoxin. After the ADC is internalized, the cytotoxic drug is released and kills the cancer. Due to this targeting, ideally the drug has lower side effects and gives a wider therapeutic window than other chemotherapeutic agents. These advantages have led to ADC technologies being featured in many publications, notably "The New York Times", as well as numerous scientific journals.
Lingual tonsils
Like other lymphatic tissues, the function of lingual tonsils is to prevent infections. These tonsils contain B and T lymphocytes which get activated when harmful bacteria and viruses come in contact with tonsils. B lymphocytes kill pathogens by producing antibodies against them, while T lymphocytes directly kill them by engulfing them.
Antithyroid agent
The mechanisms of action are not completely understood. Some scientists believe that anti-thyroids inhibit iodination of tyrosyl residues in thyroglobulin. It is thought that they inhibit the thyroperoxidase catalyzed oxidation reactions by acting as substrates for the postulated peroxidase-iodine complex, thus competitively inhibiting the interaction with the amino acid tyrosine. Propylthiouracil additionally may reduce the de-iodination of T4 into T3 in peripheral tissues.
Botulinum toxin
Botulinum toxin exerts its effect by cleaving key proteins required for nerve activation. First, the toxin binds specifically to nerves which use the neurotransmitter acetylcholine. Once bound to the nerve terminal, the neuron takes up the toxin into a vesicle. As the vesicle moves farther into the cell, it acidifies, activating a portion of the toxin which triggers it to push across the vesicle membrane and into the cell cytoplasm. Once inside the cytoplasm, the toxin cleaves SNARE proteins preventing the cell from releasing vesicles of neurotransmitter. This stops nerve signaling, leading to paralysis.
Altitoxin
Altitoxin has sequence homology to scorpion β-toxins, suggesting it might target sodium channels. However, its depressing action following injection into mice is not in agreement with the effect of β-toxins on sodium channels. Related scorpion toxins, which include birtoxin and bestoxin, exhibit highly divergent biological activity, indicating that the mode of action of these toxins is highly diverse.
Channel blocker
To comprehend the mechanism of channel blockers, it is critical to understand the composition of ion channels. Their main function is to contribute to the resting membrane potential of a cell via the flow of ions through a cell membrane. To accomplish this task, ions must be able to cross the hydrophobic region of a lipid bilayer membrane, an unfavorable process. To assist in ion transport, ion channels form a hydrophilic pore through the membrane which allows for the usually unfavorable transfer of hydrophilic molecules. Various ion channels have varying mechanisms of function. They include:
Molecules that act as ion channel blockers can be used in relation to any of these various channels. For example, sodium channels, which are essential to the production of action potentials, are affected by many different toxins. Tetrodotoxin (TTX), a toxin found in pufferfish, completely blocks sodium ion transportation by blocking the selectivity filter region of the channel. Much of the structure of the pores of ion channels has been elucidated from studies that used toxins to inhibit channel function.
Dyssynergia
Botulinum A Toxin (BTX A) is injected into the external sphincter via cystoscopic or ultrasound. Botox blocks the release of acetylcholine, a neurotransmitter that is needed for muscle contraction. With the release of acetylcholine inhibited, muscles will become more relaxed.
Killer yeast
Several experiments suggest that antibodies that mimic the biological activity of killer toxins have application as antifungal agents.
NCAA banned substances
Anti-Estrogens are substances that block the effects of estrogen in the body (usually to prevent tumors) and are used by athletes to counter the side effects of steroids. Anti-estrogens are clinically used in the treatment of breast cancer and to reduce the breast cancer incidence in high-risk women. Examples of anti-estrogens are: anastrozole, clomiphene, tamoxifen, and formestane.
Iris cyst
Antimitotic agents are used mainly when a cyst is resistant to all other treatments apart from surgery, since surgery is the last resort. Antimitotic agents are injected into the cyst and left inside for 5 minutes; after 5 minutes the agents are rinsed out. Antimitotic agents have the side effect of creating a small inflammation which can easily be treated with topical steroids. Antimitotic agents stop the mitose of the cells of the cyst by interfering with a particular phase of the cell cycle, which stops the cyst from growing and will eventually kill the cells and thus the cyst.