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Leupeptin
Leupeptin, also known as ''N''-acetyl-L-leucyl-L-leucyl-L-argininal, is a naturally occurring protease inhibitor that can inhibit cysteine, serine and threonine peptidases. It is often used during ''in vitro'' experiments when a specific enzymatic reaction is being studied. When cells are lysed for these studies, proteases, many of which are contained within lysosomes, are released. These proteases, if freely present in the lysate, would destroy any products from the reaction being studied, and make the experiment uninterpretable. For example, leupeptin could be used in a calpain extraction to keep calpain from being hydrolyzed by specific proteases. The suggested concentration is 1-10 μM (0.5-5 μg/ml). Leupeptin is an organic compound produced by actinomycetes, which inhibits serine, cysteine and threonine proteases. Leupeptin inhibits serine proteinases (trypsin (Ki=3.5 nM), plasmin (Ki= 3.4 nM), porcine kallikrein), and cysteine proteinases ( papain, ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leupeptin
Leupeptin, also known as ''N''-acetyl-L-leucyl-L-leucyl-L-argininal, is a naturally occurring protease inhibitor that can inhibit cysteine, serine and threonine peptidases. It is often used during ''in vitro'' experiments when a specific enzymatic reaction is being studied. When cells are lysed for these studies, proteases, many of which are contained within lysosomes, are released. These proteases, if freely present in the lysate, would destroy any products from the reaction being studied, and make the experiment uninterpretable. For example, leupeptin could be used in a calpain extraction to keep calpain from being hydrolyzed by specific proteases. The suggested concentration is 1-10 μM (0.5-5 μg/ml). Leupeptin is an organic compound produced by actinomycetes, which inhibits serine, cysteine and threonine proteases. Leupeptin inhibits serine proteinases (trypsin (Ki=3.5 nM), plasmin (Ki= 3.4 nM), porcine kallikrein), and cysteine proteinases ( papain, ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cathepsin
Cathepsins (Ancient Greek ''kata-'' "down" and ''hepsein'' "boil"; abbreviated CTS) are proteases ( enzymes that degrade proteins) found in all animals as well as other organisms. There are approximately a dozen members of this family, which are distinguished by their structure, catalytic mechanism, and which proteins they cleave. Most of the members become activated at the low pH found in lysosomes. Thus, the activity of this family lies almost entirely within those organelles. There are, however, exceptions such as cathepsin K, which works extracellularly after secretion by osteoclasts in bone resorption. Cathepsins have a vital role in mammalian cellular turnover. Classification * Cathepsin A (serine protease) * Cathepsin B (cysteine protease) * Cathepsin C (cysteine protease) * Cathepsin D (aspartyl protease) * Cathepsin E (aspartyl protease) * Cathepsin F (cysteine proteinase) * Cathepsin G (serine protease) * Cathepsin H (cysteine protease) * Cathepsin K (cysteine protea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gusperimus
Gusperimus is an immunosuppressive drug. It is a derivative of the naturally occurring HSP70 inhibitor spergualin, and inhibits the interleukin-2-stimulated maturation of T cells to the S and G2/M phases and the polarization of the T cells into IFN-gamma-secreting Th1 effector T cells, resulting in the inhibition of growth of activated naive CD4 T cells. Gusperimus was developed by Bristol-Myers Squibb. Currently, it is manufactured and sponsored for use as an orphan drug and for clinical studies by the Japanese company Euro Nippon Kayaku. The patent claim (see quotation) is that Gusperimus may be useful for a variety of hyperreactive inflammatory diseases such as autoimmune diseases. The drug is available in vials containing 100 mg each. There is little information about the pharmacokinetic properties of gusperimus. Overview The European Commission assigned orphan drug status to Gusperimus in 2001 for the treatment of granulomatosis with polyangiitis, a serious form of vas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plasmin
Plasmin is an important enzyme () present in blood that degrades many blood plasma proteins, including fibrin clots. The degradation of fibrin is termed fibrinolysis. In humans, the plasmin protein (in the zymogen form of plasminogen) is encoded by the ''PLG'' gene. Function Plasmin is a serine protease that acts to dissolve fibrin blood clots. Apart from fibrinolysis, plasmin proteolyses proteins in various other systems: It activates collagenases, some mediators of the complement system, and weakens the wall of the Graafian follicle, leading to ovulation. Plasmin is also integrally involved in inflammation. It cleaves fibrin, fibronectin, thrombospondin, laminin, and von Willebrand factor. Plasmin, like trypsin, belongs to the family of serine proteases. Plasmin is released as a zymogen called plasminogen (PLG) from the liver into the systemic circulation. Two major glycoforms of plasminogen are present in humans - type I plasminogen contains two glycosylation moieties ... [...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] |
Chymotrypsin
Chymotrypsin (, chymotrypsins A and B, alpha-chymar ophth, avazyme, chymar, chymotest, enzeon, quimar, quimotrase, alpha-chymar, alpha-chymotrypsin A, alpha-chymotrypsin) is a digestive enzyme component of pancreatic juice acting in the duodenum, where it performs proteolysis, the breakdown of proteins and polypeptides. Chymotrypsin preferentially cleaves peptide amide bonds where the side chain of the amino acid N-terminal to the scissile amide bond (the P1 position) is a large hydrophobic amino acid (tyrosine, tryptophan, and phenylalanine). These amino acids contain an aromatic ring in their side chain that fits into a hydrophobic pocket (the S1 position) of the enzyme. It is activated in the presence of trypsin. The hydrophobic and shape complementarity between the peptide substrate P1 side chain and the enzyme S1 binding cavity accounts for the substrate specificity of this enzyme. Chymotrypsin also hydrolyzes other amide bonds in peptides at slower rates, particularly tho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endoproteinase Lys-C
Endoproteinase Lys-C is a protease that cleaves proteins on the C-terminal side of lysine residues. This enzyme is naturally found in the bacterium ''Lysobacter enzymogenes'' and is commonly used in protein sequencing. Lys-C activity is optimal in the pH range 7.0 - 9.0. See also *Trypsin *Lys-N Lys-N is a metalloendopeptidase found in the mushroom ''Grifola frondosa'' that cleaves proteins on the amino side of lysine residues. Mass spectrometry Lys-N is becoming a popular protease used for protein digestion in proteomics experiments. Th ... References Bacterial enzymes Proteases EC 3.4 Post-translational modification Proteomics §gtfgf {{Enzyme-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Papain
Papain, also known as papaya proteinase I, is a cysteine protease () enzyme present in papaya (''Carica papaya'') and mountain papaya (''Vasconcellea cundinamarcensis''). It is the namesake member of the papain-like protease family. It has wide ranging commercial applications in the leather, cosmetic, textiles, detergents, food and pharmaceutical industries. In the food industry, papain is used as an active ingredient in many commercial meat tenderizers. Papain family Papain belongs to a family of related proteins, known as the papain-like protease family, with a wide variety of activities, including endopeptidases, aminopeptidases, dipeptidyl peptidases and enzymes with both exo- and endopeptidase activity. Members of the papain family are widespread, found in Baculoviridae, baculoviruses, eubacteria, yeast, and practically all protozoa, plants and mammals. The proteins are typically lysosomal or secreted, and proteolytic cleavage of the propeptide is required for enzyme activa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kallikrein
Kallikreins are a subgroup of serine proteases, enzymes capable of cleaving peptide bonds in proteins. In humans, plasma kallikrein (encoded by ''KLKB1 gene'') has no known paralogue, while tissue kallikrein-related peptidases (''KLKs'') encode a family of fifteen closely related serine proteases. These genes are localised to chromosome 19q13, forming the largest contiguous cluster of proteases within the human genome. Kallikreins are responsible for the coordination of various physiological functions including blood pressure, semen liquefaction and skin desquamation. Occurrence In 1934, Eugen Werle reported finding a substance in the pancreas of humans and various animals in such large amounts that the pancreas could be taken for its site of origin. He named it kallikrein, by derivation from the Greek word for pancreas. Since then, similar enzymes have been found in the biological fluids of humans and other mammals, as well as in some snake venoms. Venom The caterpillar known ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trypsin
Trypsin is an enzyme in the first section of the small intestine that starts the digestion of protein molecules by cutting these long chains of amino acids into smaller pieces. It is a serine protease from the PA clan superfamily, found in the digestive system of many vertebrates, where it hydrolyzes proteins. Trypsin is formed in the small intestine when its proenzyme form, the trypsinogen produced by the pancreas, is activated. Trypsin cuts peptide chains mainly at the carboxyl side of the amino acids lysine or arginine. It is used for numerous biotechnological processes. The process is commonly referred to as trypsin proteolysis or trypsinization, and proteins that have been digested/treated with trypsin are said to have been trypsinized. Trypsin was discovered in 1876 by Wilhelm Kühne and was named from the Ancient Greek word for rubbing since it was first isolated by rubbing the pancreas with glycerin. Function In the duodenum, trypsin catalyzes the hydrolysis of pept ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synthalin
Synthalin was an oral anti-diabetic drug. Discovered in 1926 it was marketed in Europe by Schering AG of Berlin as a synthetic drug with insulin-like properties that could be taken orally. However, it was toxic to the liver and kidney and was withdrawn from the market in the early 1940s. History The folk remedy Galega officinalis, French lilac (''Galega officinalis''), was used to treat the symptoms of diabetes, and towards the end of the nineteenth century it was discovered to contain guanidine. This had a hypoglycaemic effect but was very toxic to the liver. Karl Slotta at the Chemistry Institute of the University of Vienna synthesized derived compounds that had a polymethylene chain with a guanidine group at each end. These diguanides were less toxic and more potent than guanidine. In 1926, E. Frank, working in Oskar Minkowski's clinic in University of Wroclaw, Wroclaw performed a clinical trial on one of these agents. It was subsequently marketed as Synthalin by Schering AG for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Threonine Protease
Threonine proteases are a family of proteolytic enzymes harbouring a threonine (Thr) residue within the active site. The prototype members of this class of enzymes are the catalytic subunits of the proteasome, however the acyltransferases convergently evolved the same active site geometry and mechanism. Mechanism Threonine proteases use the secondary alcohol of their N-terminal threonine as a nucleophile to perform catalysis. The threonine must be N-terminal since the terminal amine of the same residue acts as a general base by polarising an ordered water which deprotonates the alcohol to increase its reactivity as a nucleophile. Catalysis takes place in two steps: * Firstly the nucleophile attacks the substrate to form a covalent acyl-enzyme intermediate, releasing the first product. * Secondly the intermediate is hydrolysed by water to regenerate the free enzyme and release the second product. ** In ornithine acyltransferase, instead of water, the substrate ornithine (th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
