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Cerastocytin
Cerastocytin is a thrombin-like serine protease in snake venom. Function overview Snake venom contains toxins capable of causing death to the reptile's prey in many various ways. Most of the toxins fall into one of the two categories: elapid (mainly neurotoxic) or viperid (mainly hemotoxic) toxins depending on the immediate cause of death. Elapid snakes cause prey to die from asphyxiation because the dominating neurotoxins inhibit cholinesterase activity, thereby leading to paralysis of all muscles, including the diaphragm. The immediate cause of death after bites of viperid snakes is a sudden drop in blood pressure or stroke as the hemotoxins, mostly prevalent in this type of venom, induce either extensive coagulation or bleeding. While snakes are categorized in this manner, venom of either type may include a number of toxic enzymes involved in neurotoxicity, hemotoxicity, nutrient digestion and other functions necessary to make the prey available for consumption. While a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thrombin
Thrombin (, ''fibrinogenase'', ''thrombase'', ''thrombofort'', ''topical'', ''thrombin-C'', ''tropostasin'', ''activated blood-coagulation factor II'', ''blood-coagulation factor IIa'', ''factor IIa'', ''E thrombin'', ''beta-thrombin'', ''gamma-thrombin'') is a serine protease, an enzyme that, in humans, is encoded by the ''F2'' gene. Prothrombin (coagulation factor II) is proteolytically cleaved to form thrombin in the clotting process. Thrombin in turn acts as a serine protease that converts soluble fibrinogen into insoluble strands of fibrin, as well as catalyzing many other coagulation-related reactions. History After the description of fibrinogen and fibrin, Alexander Schmidt hypothesised the existence of an enzyme that converts fibrinogen into fibrin in 1872. Prothrombin was discovered by Pekelharing in 1894. Physiology Synthesis Thrombin is produced by the enzymatic cleavage of two sites on prothrombin by activated Factor X (Xa). The activity of factor Xa is greatly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Serine Protease
Serine proteases (or serine endopeptidases) are enzymes that cleave peptide bonds in proteins. Serine serves as the nucleophilic amino acid at the (enzyme's) active site. They are found ubiquitously in both eukaryotes and prokaryotes. Serine proteases fall into two broad categories based on their structure: chymotrypsin-like (trypsin-like) or subtilisin-like. Classification The MEROPS protease classification system counts 16 superfamilies (as of 2013) each containing many families. Each superfamily uses the catalytic triad or dyad in a different protein fold and so represent convergent evolution of the catalytic mechanism. The majority belong to the S1 family of the PA clan (superfamily) of proteases. For superfamilies, P: superfamily, containing a mixture of nucleophile class families, S: purely serine proteases. superfamily. Within each superfamily, families are designated by their catalytic nucleophile, (S: serine proteases). Substrate specificity Serine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snake Venom
Snake venom is a highly toxic saliva containing zootoxins that facilitates in the immobilization and digestion of prey. This also provides defense against threats. Snake venom is injected by unique fangs during a bite, whereas some species are also able to spit venom. The glands that secrete zootoxins are a modification of the parotid salivary glands found in other vertebrates and are usually located on each side of the head, below and behind the eye, and enclosed in a muscular sheath. The venom is stored in large glands called alveoli in which it's stored before being conveyed by a duct to the base of channeled or tubular fangs through which it's ejected. Venom contains more than 20 different compounds, which are mostly proteins and polypeptides. The complex mixture of proteins, enzymes, and various other substances has toxic and lethal properties. Venom serves to immobilize prey. Enzymes in venom play an important role in the digestion of prey, and various other substances ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toxin
A toxin is a naturally occurring organic poison produced by metabolic activities of living cells or organisms. Toxins occur especially as a protein or conjugated protein. The term toxin was first used by organic chemist Ludwig Brieger (1849–1919) and is derived from the word toxic. 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 potentially fatal even at extremely low doses (such as botulinum toxin). Toxins are largely secondary metabolites, which are organic compounds that are not directly involved in an organism's growth, development, or reproduction, instead often aiding it in matters of defense. Terminology Toxins are often distinguished from other chemical agents strictly based on their biological origin. Le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neurotoxin
Neurotoxins are toxins that are destructive to nerve tissue (causing neurotoxicity). Neurotoxins are an extensive class of exogenous chemical neurological insultsSpencer 2000 that can adversely affect function in both developing and mature nervous tissue.Olney 2002 The term can also be used to classify endogenous compounds, which, when abnormally contacted, can prove neurologically toxic. Though neurotoxins are often neurologically destructive, their ability to specifically target neural components is important in the study of nervous systems. Common examples of neurotoxins include lead, ethanol (drinking alcohol), glutamate,Choi 1987 nitric oxide, botulinum toxin (e.g. Botox), tetanus toxin,Simpson 1986 and tetrodotoxin. Some substances such as nitric oxide and glutamate are in fact essential for proper function of the body and only exert neurotoxic effects at excessive concentrations. Neurotoxins inhibit neuron control over ion concentrations across the cell membrane, or com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hemotoxic
Hemotoxins, haemotoxins or hematotoxins are toxins that destroy red blood cells, disrupt blood clotting, and/or cause organ degeneration and generalized tissue damage. The term ''hemotoxin'' is to some degree a misnomer since toxins that damage the blood also damage other tissues. Injury from a hemotoxic agent is often very painful and can cause permanent damage and in severe cases death. Loss of an affected limb is possible even with prompt treatment. Hemotoxins are frequently employed by venomous animals, including snakes (vipers and pit vipers) and spiders (brown recluse). Animal venoms contain enzymes and other proteins that are hemotoxic or neurotoxic or occasionally both (as in the Mojave rattlesnake, the Japanese mamushi, and similar species). In addition to killing the prey, part of the function of a hemotoxic venom for some animals is to aid digestion. The venom breaks down protein in the region of the bite, making prey easier to digest. The process by which a hemotoxi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elapidae
Elapidae (, commonly known as elapids ; grc, ἔλλοψ ''éllops'' "sea-fish") is a family of snakes characterized by their permanently erect fangs at the front of the mouth. Most elapids are venomous, with the exception of the genus Emydocephalus. Many members of this family exhibit a threat display of rearing upwards while spreading out a neck flap. Elapids are endemic to tropical and subtropical regions around the world, with terrestrial forms in Asia, Australia, Africa, and the Americas and marine forms in the Pacific and Indian Oceans. Members of the family have a wide range of sizes, from the white-lipped snake to the king cobra. Most species have neurotoxic venom which is channeled by their hollow fangs, and some may contain other toxic components in various proportions. The family includes 55 genera with some 360 species and over 170 subspecies. Description Terrestrial elapids look similar to the Colubridae; almost all have long, slender bodies with smooth scales, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viperidae
The Viperidae (vipers) are a family of snakes found in most parts of the world, except for Antarctica, Australia, Hawaii, Madagascar, and various other isolated islands. They are venomous and have long (relative to non-vipers), hinged fangs that permit deep penetration and injection of their venom. Four subfamilies are currently recognized. They are also known as viperids. The name "viper" is derived from the Latin word ''vipera'', -''ae'', also meaning viper, possibly from ''vivus'' ("living") and ''parere'' ("to beget"), referring to the trait viviparity (giving live birth) common in vipers like most of the species of Boidae. Description All viperids have a pair of relatively long solenoglyphous (hollow) fangs that are used to inject venom from glands located towards the rear of the upper jaws, just behind the eyes. Each of the two fangs is at the front of the mouth on a short maxillary bone that can rotate back and forth. When not in use, the fangs fold back against the ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bothrops Jararaca
''Bothrops jararaca'' — known as the ''jararaca'' or ''yarara'' — is a highly venomous pit viper species endemic to South America in southern Brazil, Paraguay, and northern Argentina. The specific name, ''jararaca'', is derived from the Tupi words and , which mean "large snake". Within its geographic range, it is often abundant and is an important cause of snakebite. No subspecies are currently recognized. The drugs known as angiotensin converting enzyme (ACE) inhibitors, used for the treatment of hypertension and some types of congestive heart failure, were developed from a peptide found in the venom of this species. Description This is a slender and terrestrial species that grows to a maximum total length of 160 cm (63 in), although the average total length is much less. The head scalation includes 5-12 intersupraoculars that are weakly keeled, 7-9 supralabials (usually 8) of which the second is fused with the prelacunal to form a lacunolabial, and 9-13 sub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cerastes Cerastes
''Cerastes cerastes'', commonly known as the Saharan horned viperMallow D, Ludwig D, Nilson G. (2003). ''True Vipers: Natural History and Toxinology of Old World Vipers''. Malabar, Florida: Krieger Publishing Company. . or the desert horned viper,Mehrtens JM. (1987). ''Living Snakes of the World in Color''. New York: Sterling Publishers. . is a venomous species of viper native to the deserts of Northern Africa and parts of the Arabian Peninsula and Levant. It is often easily recognized by the presence of a pair of supraocular "horns", although hornless individuals do occur. Three subspecies have been described. Description The average total length (body and tail) is , with a maximum total length of . Females are larger than males. One of the most distinctive characteristics of this species is the presence of supraorbital "horns", one over each eye. However, these may be reduced in size or absent (see genus ''Cerastes''). The eyes are prominent and set on the sides of the head. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bothrops Atrox
''Bothrops atrox'' — also known as the common lancehead, ''fer-de-lance'', ''barba amarilla''Campbell JA, Lamar WW. 2004. ''The Venomous Reptiles of the Western Hemisphere''. Comstock Publishing Associates, Ithaca and London. 870 pp. 1500 plates. and ''mapepire balsain'' — is a highly venomous pit viper species found in the tropical lowlands of northern South America east of the Andes. No subspecies are currently recognized. Taxonomy The common lancehead was one of the many reptile and amphibian species described by Carl Linnaeus in the landmark 1758 10th edition of his ''Systema Naturae'', where it was given the binomial name ''Coluber atrox''. Common names include lancehead, ''fer-de-lance'', ''barba amarilla'', and ''mapepire balsain'', among others. The Spanish common name ''barba amarilla'' (yellow beard), an allusion to the pale yellow chin color, is also used in English. In Venezuela, it is called ''mapanare''. In Colombia, it is known as ''mapaná '' (Llanos of Vi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fibrinopeptide A
The fibrinopeptides, fibrinopeptide A (FpA) and fibrinopeptide B (FpB), are peptides which are located in the central region of the fibrous glycoprotein fibrinogen (factor I) and are cleaved by the enzyme thrombin (factor IIa) to convert fibrinogen into covalently-linked fibrin (factor IA) monomers. The N-terminal FpA is cleaved from the Aα chains of fibrinogen and FpB from the Bβ chains of fibrinogen, with FpA released before FpB. Subsequent to their formation, fibrin monomers are converted to cross-linked fibrin polymers by the action of thrombin-activated factor XIII (fibrin stabilizing factor), and these fibrin polymers form the backbone of a thrombus (blood clot). Hence, the fibrinopeptides are sensitive markers of fibrinogenesis (fibrin generation), thrombin activity, and coagulation. FpA is a 16-amino acid peptide. The half-life of FpA is very short at approximately 3 to 5 minutes. Hence, FpA levels provide a relatively transient measure of coagulation activ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
