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Taipoxin
Taipoxin is a potent myo- and neurotoxin that was isolated from the venom of the coastal taipan ''Oxyuranus scutellatus'' or also known as the common taipan. Taipoxin like many other pre-synaptic neurotoxins are phospholipase A2 (PLA2) toxins, which inhibit/complete block the release of the motor transmitter acetylcholine and lead to death by paralysis of the respiratory muscles (asphyxia). It is the most lethal neurotoxin isolated from any snake venom to date. The molecular mass of the heterotrimer is about 46,000 Dalton; comprising 1:1:1 α, β and γ monomers. Median lethal dose (LD50) for mice is around 1–2 μg/kg ( subcutaneous injection). History Taipoxin and other PLA2 toxins have evolved from the digestive PLA2 enzymes. The venom still functions with the almost identical multi-disulphide-bridged protein PLA2 scaffold, which causes the hydrolytic mechanism of the enzyme. However it is thought that under strict evolution selection pressures of prey immobilis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Notexin
Notexin is a toxin produced by the tiger snake (''Notechis scutatus''). It is a myotoxic and presynaptic, neurotoxic phospholipase A2 (PLA2s). These are enzymes that hydrolyze the bond between a fatty acid tail and glycerol in fatty acids on the 2-position. History The name notexin comes from the fact that this toxin was first found to be the major component in the venom of the tiger snake. The name notexin is thus a combination of the genus name ''Notechis'' and the word toxin. The tiger snake was first described by Wilhelm Peters in 1861. The toxin was first purified more than a hundred years later in 1972 by Karlsson ''et al''. This prompted more research into notexin. Structure Notexin consists of a single molecule. This molecule is a single-peptide chain of 119 amino acid residues that are cross-linked with 7 disulfide-bridges. X-ray diffraction has been used to determine the crystal structure of notexin and led to the conclusion that notexin belongs to either the P3 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myotoxin
Myotoxins are small, basic peptides found in snake venoms (e.g. rattlesnakes) and lizard venoms (e.g. Mexican beaded lizard). This involves a non-enzymatic mechanism that leads to severe muscle necrosis. These peptides act very quickly, causing instantaneous paralysis to prevent prey from escaping and eventually death due to diaphragmatic paralysis. The first myotoxin to be identified and isolated was crotamine, from the venom of ''Crotalus durissus terrificus'', a tropical South American rattlesnake, by Brazilian scientist José Moura Gonçalves, in the 1950s. Its biological actions, molecular structure and gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ... responsible for its synthesis were all elucidated in the last two decades. References {{reflist Vertebrate toxins I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proteolysis
Proteolysis is the breakdown of proteins into smaller polypeptides or amino acids. Uncatalysed, the hydrolysis of peptide bonds is extremely slow, taking hundreds of years. Proteolysis is typically catalysed by cellular enzymes called proteases, but may also occur by intra-molecular digestion. Proteolysis in organisms serves many purposes; for example, digestive enzymes break down proteins in food to provide amino acids for the organism, while proteolytic processing of a polypeptide chain after its synthesis may be necessary for the production of an active protein. It is also important in the regulation of some physiological and cellular processes including apoptosis, as well as preventing the accumulation of unwanted or misfolded proteins in cells. Consequently, abnormality in the regulation of proteolysis can cause disease. Proteolysis can also be used as an analytical tool for studying proteins in the laboratory, and it may also be used in industry, for example in food proc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antivenom
Antivenom, also known as antivenin, venom antiserum, and antivenom immunoglobulin, is a specific treatment for envenomation. It is composed of antibodies and used to treat certain venomous bites and stings. Antivenoms are recommended only if there is significant toxicity or a high risk of toxicity. The specific antivenom needed depends on the species involved. It is given by injection. Side effects may be severe. They include serum sickness, shortness of breath, and allergic reactions including anaphylaxis. Antivenom is traditionally made by collecting venom from the relevant animal and injecting small amounts of it into a domestic animal. The antibodies that form are then collected from the domestic animal's blood and purified. Versions are available for spider bites, snake bites, fish stings, and scorpion stings. Due to the high cost of producing antibody-based antivenoms and their short shelf lives when not refrigerated, alternative methods of production of antivenoms ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binding Constant
The binding constant, or affinity constant/association constant, is a special case of the equilibrium constant ''K'', and is the inverse of the dissociation constant. It is associated with the binding and unbinding reaction of receptor (R) and ligand (L) molecules, which is formalized as: :R + L RL The reaction is characterized by the on-rate constant ''k''on and the off-rate constant ''k''off, which have units of M−1 s−1 and s−1, respectively. In equilibrium, the forward binding transition R + L → RL should be balanced by the backward unbinding transition RL → R + L. That is, :k_\,[]\,[] = k_\,[], where [R], [L] and [RL] represent the concentration of unbound free receptors, the concentration of unbound free ligand and the concentration of receptor-ligand complexes. The binding constant ''K''a is defined by :K_ = = . An often considered quantity is the dissociation constant ''K''d ≡ , which has the unit of concentration, despite the fact that str ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catecholamine
A catecholamine (; abbreviated CA) is a monoamine neurotransmitter, an organic compound that has a catechol (benzene with two hydroxyl side groups next to each other) and a side-chain amine. Catechol can be either a free molecule or a substituent of a larger molecule, where it represents a 1,2-dihydroxybenzene group. Catecholamines are derived from the amino acid tyrosine, which is derived from dietary sources as well as synthesis from phenylalanine. Catecholamines are water-soluble and are 50% bound to plasma proteins in circulation. Included among catecholamines are epinephrine (adrenaline), norepinephrine (noradrenaline), and dopamine. Release of the hormones epinephrine and norepinephrine from the adrenal medulla of the adrenal glands is part of the fight-or-flight response. Tyrosine is created from phenylalanine by hydroxylation by the enzyme phenylalanine hydroxylase. Tyrosine is also ingested directly from dietary protein. Catecholamine-secreting cells use sev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromaffin Cell
Chromaffin cells, also called pheochromocytes (or phaeochromocytes), are neuroendocrine cells found mostly in the medulla of the adrenal glands in mammals. These cells serve a variety of functions such as serving as a response to stress, monitoring carbon dioxide and oxygen concentrations in the body, maintenance of respiration and the regulation of blood pressure. They are in close proximity to pre-synaptic sympathetic ganglia of the sympathetic nervous system, with which they communicate, and structurally they are similar to post-synaptic sympathetic neurons. In order to activate chromaffin cells, the splanchnic nerve of the sympathetic nervous system releases acetylcholine, which then binds to nicotinic acetylcholine receptors on the adrenal medulla. This causes the release of catecholamines. The chromaffin cells release catecholamines: ~80% of adrenaline ( epinephrine) and ~20% of noradrenaline (norepinephrine) into systemic circulation for systemic effects on multiple org ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edema
Edema, also spelled oedema, and also known as fluid retention, dropsy, hydropsy and swelling, is the build-up of fluid in the body's Tissue (biology), tissue. Most commonly, the legs or arms are affected. Symptoms may include skin which feels tight, the area may feel heavy, and joint stiffness. Other symptoms depend on the underlying cause. Causes may include Chronic venous insufficiency, venous insufficiency, heart failure, kidney problems, hypoalbuminemia, low protein levels, liver problems, deep vein thrombosis, infections, angioedema, certain medications, and lymphedema. It may also occur after prolonged sitting or standing and during menstruation or pregnancy. The condition is more concerning if it starts suddenly, or pain or shortness of breath is present. Treatment depends on the underlying cause. If the underlying mechanism involves Hypernatremia, sodium retention, decreased salt intake and a diuretic may be used. Elevating the legs and support stockings may be useful ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myotoxin
Myotoxins are small, basic peptides found in snake venoms (e.g. rattlesnakes) and lizard venoms (e.g. Mexican beaded lizard). This involves a non-enzymatic mechanism that leads to severe muscle necrosis. These peptides act very quickly, causing instantaneous paralysis to prevent prey from escaping and eventually death due to diaphragmatic paralysis. The first myotoxin to be identified and isolated was crotamine, from the venom of ''Crotalus durissus terrificus'', a tropical South American rattlesnake, by Brazilian scientist José Moura Gonçalves, in the 1950s. Its biological actions, molecular structure and gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ... responsible for its synthesis were all elucidated in the last two decades. References {{reflist Vertebrate toxins I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Size-exclusion Chromatography
Size-exclusion chromatography (SEC), also known as molecular sieve chromatography, is a chromatographic method in which molecules in solution are separated by their size, and in some cases molecular weight. It is usually applied to large molecules or macromolecular complexes such as proteins and industrial polymers. Typically, when an aqueous solution is used to transport the sample through the column, the technique is known as gel-filtration chromatography, versus the name gel permeation chromatography, which is used when an organic solvent is used as a mobile phase. The chromatography column is packed with fine, porous beads which are commonly composed of dextran, agarose, or polyacrylamide polymers. The pore sizes of these beads are used to estimate the dimensions of macromolecules. SEC is a widely used polymer characterization method because of its ability to provide good molar mass distribution (Mw) results for polymers. Applications The main application of gel-filtration chr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypotension
Hypotension is low blood pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood. Blood pressure is indicated by two numbers, the systolic blood pressure (the top number) and the diastolic blood pressure (the bottom number), which are the maximum and minimum blood pressures, respectively. A systolic blood pressure of less than 90 millimeters of mercury (mmHg) or diastolic of less than 60 mmHg is generally considered to be hypotension. Different numbers apply to children. However, in practice, blood pressure is considered too low only if noticeable symptoms are present. Symptoms include dizziness or lightheadedness, confusion, feeling tired, weakness, headache, blurred vision, nausea, neck or back pain, an irregular heartbeat or feeling that the heart is skipping beats or fluttering, or fainting. Hypotension is the opposite of hypertension, which is high blood pressure. It is best understood as a physiological st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anticoagulant
Anticoagulants, commonly known as blood thinners, are chemical substances that prevent or reduce coagulation of blood, prolonging the clotting time. Some of them occur naturally in blood-eating animals such as leeches and mosquitoes, where they help keep the bite area unclotted long enough for the animal to obtain some blood. As a class of medications, anticoagulants are used in therapy for thrombotic disorders. Oral anticoagulants (OACs) are taken by many people in pill or tablet form, and various intravenous anticoagulant dosage forms are used in hospitals. Some anticoagulants are used in medical equipment, such as sample tubes, blood transfusion bags, heart–lung machines, and dialysis equipment. One of the first anticoagulants, warfarin, was initially approved as a rodenticide. Anticoagulants are closely related to antiplatelet drugs and thrombolytic drugs by manipulating the various pathways of blood coagulation. Specifically, antiplatelet drugs inhibit platelet agg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
