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Aureolysin
Aureolysin (, ''protease III, staphylococcal metalloprotease,'' ''Staphylococcus aureus neutral proteinase'') is an extracellular metalloprotease expressed by ''Staphylococcus aureus''. This protease is a major contributor to the bacterium's virulence, or ability to cause disease, by cleaving host factors of the innate immune system as well as regulating S. aureus secreted toxins and cell wall proteins. To catalyze its enzymatic activities, aureolysin requires zinc and calcium which it obtains from the extracellular environment within the host. Genetics Aureolysin is expressed from the gene ''aur'', which is located on a monocistronic operon. The gene exists in two allelic forms but the sequence is highly conserved with 89% homology between the two. The gene contains a coding sequence of 1,527 nucleotides that translates into a pre-pro-form of the enzyme that is 509 amino acids long. Of the 509 amino acids, only 301 denote the mature form of aureolysin. After translation, the pre- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metalloprotease
A metalloproteinase, or metalloprotease, is any protease enzyme whose catalytic mechanism involves a metal. An example is ADAM12 which plays a significant role in the fusion of muscle cells during embryo development, in a process known as myogenesis. Most metalloproteases require zinc, but some use cobalt. The metal ion is coordinated to the protein via three ligands. The ligands coordinating the metal ion can vary with histidine, glutamate, aspartate, lysine, and arginine. The fourth coordination position is taken up by a labile water molecule. Treatment with chelating agents such as EDTA leads to complete inactivation. EDTA is a metal chelator that removes zinc, which is essential for activity. They are also inhibited by the chelator orthophenanthroline. Classification There are two subgroups of metalloproteinases: * Exopeptidases, metalloexopeptidases ( EC number: 3.4.17). * Endopeptidases, metalloendopeptidases (3.4.24). Well known metalloendopeptidases include ADAM prot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C3-convertase
C3 convertase (''C4bC2b'', formerly ''C4b2a'') belongs to family of serine proteases and is necessary in innate immunity as a part of the complement system which eventuate in opsonisation of particles, release of inflammatory peptides, C5 convertase formation and cell lysis. C3 convertase can be used to refer to the form produced in the alternative pathway (C3bBb) or the classical and lectin pathways (C4bC2b, formerly C4b2a). Once formed, both C3 convertases will catalyze the proteolytic cleavage of C3 into C3a and C3b (hence the name "C3-convertase"). The smaller fragment called C3a serves to increase vascular permeability and promote extravasation of phagocytes, while the larger C3b fragment can be used as an opsonin or bind to either type of C3 convertase to form the trimolecular C5 convertase to activate C5 for the membrane attack complex. Formation C3 convertase formation can occur in three different pathways: the classical, lectin, and alternative pathways. Alter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Α2-antiplasmin
Alpha 2-antiplasmin (or α2-antiplasmin or plasmin inhibitor) is a serine protease inhibitor (serpin) responsible for inactivating plasmin. Plasmin is an important enzyme that participates in fibrinolysis and degradation of various other proteins. This protein is encoded by the SERPINF2 gene. Role in disease Very few cases (<20) of A2AP deficiency have been described. As plasmin degrades blood clots, impaired inhibition of plasmin leads to a bleeding tendency, which was severe in the cases reported. In liver cirrhosis, there is decreased production of alpha 2-antiplasmin, leading to decreased inactivation of plasmin and an increase in fibrinolysis. This is associated with an increase risk of bleeding in liver disease. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Urokinase
Urokinase, also known as urokinase-type plasminogen activator (uPA), is a serine protease present in humans and other animals. The human urokinase protein was discovered, but not named, by McFarlane and Pilling in 1947. Urokinase was originally isolated from human urine, and it is also present in the blood and in the extracellular matrix of many tissues. The primary physiological substrate of this enzyme is plasminogen, which is an inactive form (zymogen) of the serine protease plasmin. Activation of plasmin triggers a proteolytic cascade that, depending on the physiological environment, participates in thrombolysis or extracellular matrix degradation. This cascade had been involved in vascular diseases and cancer progression. Urokinase is encoded in humans by the ''PLAU'' gene, which stands for "plasminogen activator, urokinase". The same symbol represents the gene in other animal species. Function The ''PLAU'' gene encodes a serine protease () involved in degradation of the e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Staphylokinase
Staphylokinase (SAK; also known as staphylococcal fibrinolysin or Müller's factor) is a protein produced by ''Staphylococcus aureus''. It contains 136 amino acid residues and has a molecular mass of 15kDa. Synthesis of staphylokinase occurs in late exponential phase. It is similar to streptokinase. Staphylokinase is positively regulated by the "agr" gene regulator. It activates plasminogen to form plasmin, which digests fibrin clots. This disrupts the fibrin meshwork which forms to keep infections localized. Staphylokinase interacts with plasminogen to form a 1:1 complex that exposes the active site of the plasminogen molecule. The plasmin Sak complex is neutralized by α2- antiplasmin in plasma in the absence of fibrin, resulting in lysis. However, in the presence of fibrin, the inhibition is delayed, creating a unique mechanism for fibrin selectivity in plasma. Staphylokinase also cleaves IgG and complement component C3b, inhibiting phagocytosis. Structure The full length ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fibrinolysis
Fibrinolysis is a process that prevents blood clots from growing and becoming problematic. Primary fibrinolysis is a normal body process, while secondary fibrinolysis is the breakdown of clots due to a medicine, a medical disorder, or some other cause.Dugdale, David et al.Primary or secondary fibrinolysis, Medline Plus. Retrieved 7 August 2011. In fibrinolysis, a fibrin clot, the product of coagulation, is broken down. Its main enzyme plasmin cuts the fibrin mesh at various places, leading to the production of circulating fragments that are cleared by other proteases or by the kidney and liver. Physiology Plasmin is produced in an inactive form, plasminogen, in the liver. Although plasminogen cannot cleave fibrin, it still has an affinity for it, and is incorporated into the clot when it is formed. Tissue plasminogen activator (t-PA) and urokinase are the agents that convert plasminogen to the active plasmin, thus allowing fibrinolysis to occur. t-PA is released into the blood ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coagulase
Coagulase is a protein enzyme produced by several microorganisms that enables the conversion of fibrinogen to fibrin. In the laboratory, it is used to distinguish between different types of '' Staphylococcus'' isolates. Importantly, '' S. aureus'' is generally coagulase-positive, meaning that a positive coagulase test would indicate the presence of ''S. aureus'' or any of the other 11 coagulase-positive ''Staphylococci''. A negative coagulase test would instead show the presence of coagulase-negative organisms such as ''S. epidermidis'' or '' S. saprophyticus''. However, it is now known that not all ''S. aureus'' are coagulase-positive. Whereas coagulase-positive ''Staphylococci'' are usually pathogenic, coagulase-negative ''Staphylococci'' are more often associated with opportunistic infection. It is also produced by ''Yersinia pestis''. Coagulase reacts with prothrombin in the blood. The resulting complex is called ''staphylothrombin'', which enables the enzyme to act as a prot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coagulation
Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a blood clot. It potentially results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The mechanism of coagulation involves activation, adhesion and aggregation of platelets, as well as deposition and maturation of fibrin. Coagulation begins almost instantly after an injury to the endothelium lining a blood vessel. Exposure of blood to the subendothelial space initiates two processes: changes in platelets, and the exposure of subendothelial tissue factor to plasma factor VII, which ultimately leads to cross-linked fibrin formation. Platelets immediately form a plug at the site of injury; this is called ''primary hemostasis. Secondary hemostasis'' occurs simultaneously: additional coagulation (clotting) factors beyond factor VII ( listed below) respond in a cascade to form fibrin strands, which strengthen the platelet plug. Disorders of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LL37
Cathelicidin antimicrobial peptide (CAMP) is a polypeptide that is primarily stored in the lysosomes of macrophages and polymorphonuclear leukocytes (PMNs); in humans, the ''CAMP'' gene encodes the peptide precursor CAP-18 (18 kDa), which is processed by proteinase 3-mediated extracellular cleavage into the active form LL-37. LL-37 is the only peptide in the Cathelicidin family found in the human body. Cathelicidin peptides are dual-natured molecules called amphiphiles: one end of the molecule is attracted to water and repelled by fats and proteins, and the other end is attracted to fat and proteins and repelled by water. Members of this family react to pathogens by disintegrating, damaging, or puncturing cell membranes. Cathelicidins thus serve a critical role in mammalian innate immune defense against invasive bacterial infection. The cathelicidin family of peptides are classified as antimicrobial peptides (AMPs). The AMP family also includes the defensins. Whilst the defensins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Α1-antitrypsin
Alpha-1 antitrypsin or α1-antitrypsin (A1AT, α1AT, A1A, or AAT) is a protein belonging to the serpin superfamily. It is encoded in humans by the ''SERPINA1'' gene. A protease inhibitor, it is also known as alpha1–proteinase inhibitor (A1PI) or alpha1-antiproteinase (A1AP) because it inhibits various proteases (not just trypsin). In older biomedical literature it was sometimes called serum trypsin inhibitor (STI, dated terminology), because its capability as a trypsin inhibitor was a salient feature of its early study. As a type of enzyme inhibitor, it protects tissues from enzymes of inflammatory cells, especially neutrophil elastase, and has a reference range in blood of 0.9–2.3 g/L (in the US the reference range is expressed as mg/dL or micromoles), but the concentration can rise manyfold upon acute inflammation. When the blood contains inadequate amounts of A1AT or functionally defective A1AT (such as in alpha-1 antitrypsin deficiency), neutrophil elastase is exce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha 1-antichymotrypsin
Alpha 1-antichymotrypsin (symbol α1AC, A1AC, or a1ACT) is an alpha globulin glycoprotein that is a member of the serpin superfamily. In humans, it is encoded by the ''SERPINA3'' gene. Function Alpha 1-antichymotrypsin inhibits the activity of certain enzymes called proteases, such as cathepsin G that is found in neutrophils, and chymases found in mast cells, by cleaving them into a different shape or conformation. This activity protects some tissues, such as the lower respiratory tract, from damage caused by proteolytic enzymes. This protein is produced in the liver, and is an acute phase protein that is induced during inflammation. Clinical significance Deficiency of this protein has been associated with liver disease. Mutations have been identified in patients with Parkinson disease and chronic obstructive pulmonary disease. Alpha 1-antichymotrypsin is also associated with the pathogenesis of Alzheimer's disease as it enhances the formation of amyloid-fibrils in thi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ficolin
Ficolins are pattern recognition receptors that bind to acetyl groups present in the carbohydrates of bacterial surfaces and mediate activation of the lectin pathway of the complement cascade. Structure Ficolins (Fi+Col+Lin) are a group of oligomeric lectins with N-terminal collagen-like domain and a C-terminal fibrinogen-like domain. The primary ficolin structure contains 288 amino acids. The combination of collagen-like and fibrinogen-like domain allows the protein to form a basic subunit containing a triple helical tail and a trio of globural heads. Ficolins are produced in the liver by hepatocytes and in the lung by alveolar cells type II, neutrophils and monocytes. Role in innate immunity We now know that innate immune recognition mechanisms are sophisticated. Exocrine secretions provide a variety of soluble factors that are able to protect the body from potential pathogens. Together with pentraxins, collectins and C1q molecules, ficolins constitute the soluble pattern-r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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