Trypsin | |||||||||
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Identifiers | |||||||||
EC no. | 3.4.21.4 | ||||||||
CAS no. | 9002-07-7 | ||||||||
Databases | |||||||||
IntEnz | IntEnz view | ||||||||
BRENDA | BRENDA entry | ||||||||
ExPASy | NiceZyme view | ||||||||
KEGG | KEGG entry | ||||||||
MetaCyc | metabolic pathway | ||||||||
PRIAM | profile | ||||||||
PDB structures | RCSB PDB PDBe PDBsum | ||||||||
Gene Ontology | AmiGO / QuickGO | ||||||||
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Trypsin | |||||||||
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Identifiers | |||||||||
Symbol | Trypsin | ||||||||
Pfam | PF00089 | ||||||||
InterPro | IPR001254 | ||||||||
SMART | SM00020 | ||||||||
PROSITE | PDOC00124 | ||||||||
MEROPS | S1 | ||||||||
SCOP2 | 1c2g / SCOPe / SUPFAM | ||||||||
CDD | cd00190 | ||||||||
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Trypsin is an enzyme in the first section of the small intestine that starts the digestion of protein molecules by cutting 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. [2] [3] 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 trypsinogen proteolysis or trypsinization, and proteins that have been digested/treated with trypsin are said to have been trypsinized. [4]
Trypsin was discovered in 1876 by Wilhelm Kühne. [5] Although many sources say that Kühne named trypsin from the Ancient Greek word for rubbing, 'tripsis', because the enzyme was first isolated by rubbing the pancreas with glass powder and alcohol, in fact Kühne named trypsin from the Ancient Greek word 'thrýpto' which means 'I break' or 'I break apart'. [6]
In the duodenum, trypsin catalyzes the hydrolysis of peptide bonds, breaking down proteins into smaller peptides. The peptide products are then further hydrolyzed into amino acids via other proteases, rendering them available for absorption into the blood stream. Tryptic digestion is a necessary step in protein absorption, as proteins are generally too large to be absorbed through the lining of the small intestine. [7]
Trypsin is produced as the inactive zymogen trypsinogen in the pancreas. When the pancreas is stimulated by cholecystokinin, it is then secreted into the first part of the small intestine (the duodenum) via the pancreatic duct. Once in the small intestine, the enzyme enterokinase (also called enteropeptidase) activates trypsinogen into trypsin by proteolytic cleavage. The trypsin then activates additional trypsin, chymotrypsin and carboxypeptidase.
The enzymatic mechanism is similar to that of other serine proteases. These enzymes contain a catalytic triad consisting of histidine-57, aspartate-102, and serine-195. [8] This catalytic triad was formerly called a charge relay system, implying the abstraction of protons from serine to histidine and from histidine to aspartate, but owing to evidence provided by NMR that the resultant alkoxide form of serine would have a much stronger pull on the proton than does the imidazole ring of histidine, current thinking holds instead that serine and histidine each have effectively equal share of the proton, forming short low-barrier hydrogen bonds therewith. [9] [ page needed ] By these means, the nucleophilicity of the active site serine is increased, facilitating its attack on the amide carbon during proteolysis. The enzymatic reaction that trypsin catalyzes is thermodynamically favorable, but requires significant activation energy (it is "kinetically unfavorable"). In addition, trypsin contains an "oxyanion hole" formed by the backbone amide hydrogen atoms of Gly-193 and Ser-195, which through hydrogen bonding stabilize the negative charge which accumulates on the amide oxygen after nucleophilic attack on the planar amide carbon by the serine oxygen causes that carbon to assume a tetrahedral geometry. Such stabilization of this tetrahedral intermediate helps to reduce the energy barrier of its formation and is concomitant with a lowering of the free energy of the transition state. Preferential binding of the transition state is a key feature of enzyme chemistry.
The negative aspartate residue (Asp 189) located in the catalytic pocket (S1) of trypsin is responsible for attracting and stabilizing positively charged lysine and/or arginine, and is, thus, responsible for the specificity of the enzyme. This means that trypsin predominantly cleaves proteins at the carboxyl side (or "C-terminal side") of the amino acids lysine and arginine except when either is bound to a C-terminal proline, [10] although large-scale mass spectrometry data suggest cleavage occurs even with proline. [11] Trypsin is considered an endopeptidase, i.e., the cleavage occurs within the polypeptide chain rather than at the terminal amino acids located at the ends of polypeptides.
Human trypsin has an optimal operating temperature of about 37 °C. [12] In contrast, the Atlantic cod has several types of trypsins for the poikilotherm fish to survive at different body temperatures. Cod trypsins include trypsin I with an activity range of 4 to 65 °C (39 to 149 °F) and maximal activity at 55 °C (131 °F), as well as trypsin Y with a range of 2 to 30 °C (36 to 86 °F) and a maximal activity at 21 °C (70 °F). [13]
As a protein, trypsin has various molecular weights depending on the source. For example, a molecular weight of 23.3 kDa is reported for trypsin from bovine and porcine sources.
The activity of trypsin is not affected by the enzyme inhibitor tosyl phenylalanyl chloromethyl ketone, TPCK, which deactivates chymotrypsin.
Trypsin should be stored at very cold temperatures (between −20 and −80 °C) to prevent autolysis, which may also be impeded by storage of trypsin at pH 3 or by using trypsin modified by reductive methylation. When the pH is adjusted back to pH 8, activity returns.
These human genes encode proteins with trypsin enzymatic activity:
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Other isoforms of trypsin may also be found in other organisms.
Activation of trypsin from proteolytic cleavage of trypsinogen in the pancreas can lead to a series of events that cause pancreatic self-digestion, resulting in pancreatitis. One consequence of the autosomal recessive disease cystic fibrosis is a deficiency in transport of trypsin and other digestive enzymes from the pancreas. This leads to the disorder termed meconium ileus, which involves intestinal obstruction (ileus) due to overly thick meconium, which is normally broken down by trypsin and other proteases, then passed in feces. [14]
Trypsin is available in high quantity in pancreases, and can be purified rather easily. Hence, it has been used widely in various biotechnological processes.
In a tissue culture lab, trypsin is used to resuspend cells adherent to the cell culture dish wall during the process of harvesting cells. [15] Some cell types adhere to the sides and bottom of a dish when cultivated in vitro . Trypsin is used to cleave proteins holding the cultured cells to the dish, so that the cells can be removed from the plates.
Trypsin can also be used to dissociate dissected cells (for example, prior to cell fixing and sorting).
Trypsin can be used to break down casein in breast milk. If trypsin is added to a solution of milk powder, the breakdown of casein causes the milk to become translucent. The rate of reaction can be measured by using the amount of time needed for the milk to turn translucent.
Trypsin is commonly used in biological research during proteomics experiments to digest proteins into peptides for mass spectrometry analysis, e.g. in-gel digestion. Trypsin is particularly suited for this, since it has a very well defined specificity, as it hydrolyzes only the peptide bonds in which the carbonyl group is contributed either by an arginine or lysine residue.
Trypsin can also be used to dissolve blood clots in its microbial form and treat inflammation in its pancreatic form.
In veterinary medicine, trypsin is an ingredient in wound spray products, such as Debrisol, to dissolve dead tissue and pus in wounds in horses, cattle, dogs, and cats. [16]
In India, Trypsin - Chymotrypsin is widely prescribed for inflammation reduction during laryngitis and surgery recovery. Use outside India is not well documented and most papers written on its effectivity in the aforementioned situations have been funded by Torrent Pharmaceuticals which is one major brand that makes these tablets in India. [17] [18]
Commercial protease preparations usually consist of a mixture of various protease enzymes that often includes trypsin. These preparations are widely used in food processing: [19]
To prevent the action of active trypsin in the pancreas, which can be highly damaging, inhibitors such as BPTI and SPINK1 in the pancreas and α1-antitrypsin in the serum are present as part of the defense against its inappropriate activation. Any trypsin prematurely formed from the inactive trypsinogen is then bound by the inhibitor. The protein-protein interaction between trypsin and its inhibitors is one of the tightest bound, and trypsin is bound by some of its pancreatic inhibitors nearly irreversibly. [20] In contrast with nearly all known protein assemblies, some complexes of trypsin bound by its inhibitors do not readily dissociate after treatment with 8M urea. [21]
Trypsin inhibitors can serve as tools when addressing metabolic and obesity disorders. Metabolic disorders, obesity, and being overweight are known to increase non-communicable chronic disease prevalence. [22] It is of public health policy interest to explore various ways to mitigate this occurrence including use of trypsin inhibitors. These inhibitors have capabilities of reducing colon, breast, skin, and prostate cancer by way of radioprotective and anticarcinogenic activity. Trypsin inhibitors can act as regulatory mechanisms to control release of neutrophil proteases and avoid significant tissue damage. [22] In regards to cardiovascular conditions associated with unproductive serine protease activity, trypsin inhibitors can block their activity in platelet aggregation, fibrinolysis, coagulation, and blood coagulation.
The multifunctionality of trypsin inhibitors includes being potential protease inhibitors for AMP activity. [23] While the antibacterial action mechanisms of trypsin inhibitors are unclear, studies have aimed to study their mechanisms as potential applications in bacterial infection treatments. [23] Research and scanning microscopy showed antibacterial effects on bacterial membranes from Staphylococcus aureus . [23] Trypsin inhibitors from amphibian skin showed bacterial death promotion that affected the cell wall and membrane of Staphylococcus aureus. [23] Studies also analyzed antibacterial actions in trypsin inhibitor peptides, proteins, and E. coli . The results showed sufficient bacterial growth prevention. However, trypsin inhibitors have to meet certain criteria to be utilized in foods and medical treatments. [23]
Trypsin digestion of extra cellular matrix is a common practice in cell culture. However, this enzymatic degradation of the cells can negatively effect cell viability and surface markers, especially in stem cells. There are gentler alternatives than trypsin such as Accutase which doesn't effect surface markers such as cd14, cd117, cd49f, cd292. [24] [25] However Accutase decreases the surface levels of FasL and Fas receptor on macrophages, these receptors are associated with cell cytotoxicity in the immune system and can also facilitate apoptosis-related cell death. [26]
ProAlanase could also serve as an alternative to Trypsin in proteomic applications. [27] ProAlanase is an Aspergillus niger fungus protease that can achieve high proteolytic activity and specificity for digestion under the correct conditions. [27] ProAnalase, the acidic prolyl-endopeptidase protease, previously studied as An-PEP, has been observed in various experiments to define its specificity. [27] ProAnalase performed optimally in LC-MS applications with short digestion times and highly acidic pH. [27]
Chymotrypsin (EC 3.4.21.1, 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 those containing leucine at the P1 position.
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.
A protease is an enzyme that catalyzes proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the formation of new protein products. They do this by cleaving the peptide bonds within proteins by hydrolysis, a reaction where water breaks bonds. Proteases are involved in numerous biological pathways, including digestion of ingested proteins, protein catabolism, and cell signaling.
Digestion is the breakdown of large insoluble food compounds into small water-soluble components so that they can be absorbed into the blood plasma. In certain organisms, these smaller substances are absorbed through the small intestine into the blood stream. Digestion is a form of catabolism that is often divided into two processes based on how food is broken down: mechanical and chemical digestion. The term mechanical digestion refers to the physical breakdown of large pieces of food into smaller pieces which can subsequently be accessed by digestive enzymes. Mechanical digestion takes place in the mouth through mastication and in the small intestine through segmentation contractions. In chemical digestion, enzymes break down food into the small compounds that the body can use.
Serine proteases 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.
Digestive enzymes take part in the chemical process of digestion, which follows the mechanical process of digestion. Food consists of macromolecules of proteins, carbohydrates, and fats that need to be broken down chemically by digestive enzymes in the mouth, stomach, pancreas, and duodenum, before being able to be absorbed into the bloodstream. Initial breakdown is achieved by chewing (mastication) and the use of digestive enzymes of saliva. Once in the stomach further mechanical churning takes place mixing the food with secreted gastric acid. Digestive gastric enzymes take part in some of the chemical process needed for absorption. Most of the enzymatic activity, and hence absorption takes place in the duodenum.
Trypsinogen is the precursor form of trypsin, a digestive enzyme. It is produced by the pancreas and found in pancreatic juice, along with amylase, lipase, and chymotrypsinogen. It is cleaved to its active form, trypsin, by enteropeptidase, which is found in the intestinal mucosa. Once activated, the trypsin can cleave more trypsinogen into trypsin, a process called autoactivation. Trypsin cleaves the peptide bond on the carboxyl side of basic amino acids such as arginine and lysine.
Enteropeptidase is an enzyme produced by cells of the duodenum and is involved in digestion in humans and other animals. Enteropeptidase converts trypsinogen into its active form trypsin, resulting in the subsequent activation of pancreatic digestive enzymes. Absence of enteropeptidase results in intestinal digestion impairment.
A catalytic triad is a set of three coordinated amino acid residues that can be found in the active site of some enzymes. Catalytic triads are most commonly found in hydrolase and transferase enzymes. An acid-base-nucleophile triad is a common motif for generating a nucleophilic residue for covalent catalysis. The residues form a charge-relay network to polarise and activate the nucleophile, which attacks the substrate, forming a covalent intermediate which is then hydrolysed to release the product and regenerate free enzyme. The nucleophile is most commonly a serine or cysteine, but occasionally threonine or even selenocysteine. The 3D structure of the enzyme brings together the triad residues in a precise orientation, even though they may be far apart in the sequence.
Cysteine proteases, also known as thiol proteases, are hydrolase enzymes that degrade proteins. These proteases share a common catalytic mechanism that involves a nucleophilic cysteine thiol in a catalytic triad or dyad.
A trypsin inhibitor (TI) is a protein and a type of serine protease inhibitor (serpin) that reduces the biological activity of trypsin by controlling the activation and catalytic reactions of proteins. Trypsin is an enzyme involved in the breakdown of many different proteins, primarily as part of digestion in humans and other animals such as monogastrics and young ruminants. Serpins – including trypsin inhibitors – are irreversible and suicide substrate-like inhibitors.
Pancreatic elastase is a form of elastase that is produced in the acinar cells of the pancreas, initially produced as an inactive zymogen and later activated in the duodenum by trypsin. Elastases form a subfamily of serine proteases, characterized by a distinctive structure consisting of two beta barrel domains converging at the active site that hydrolyze amides and esters amongst many proteins in addition to elastin, a type of connective tissue that holds organs together. Pancreatic elastase 1 is a serine endopeptidase, a specific type of protease that has the amino acid serine at its active site. Although the recommended name is pancreatic elastase, it can also be referred to as elastase-1, pancreatopeptidase, PE, or serine elastase.
Aminopeptidases are enzymes that catalyze the cleavage of amino acids from the N-terminus (beginning), of proteins or peptides. They are found in many organisms; in the cell, they are found in many organelles, in the cytosol, and as membrane proteins. Aminopeptidases are used in essential cellular functions, and are often zinc metalloenzymes, containing a zinc cofactor.
Protein metabolism denotes the various biochemical processes responsible for the synthesis of proteins and amino acids (anabolism), and the breakdown of proteins by catabolism.
Trypsin-1, also known as cationic trypsinogen, is a protein that in humans is encoded by the PRSS1 gene. Trypsin-1 is the main isoform of trypsinogen secreted by pancreas, the others are trypsin-2, and trypsin-3 (meso-trypsinogen).
Kallikrein-6 is a protein that in humans is encoded by the KLK6 gene. Kallikrein-6 is also referred to as neurosin, protease M, hK6, or zyme. It is a 223 amino acid sequence, derived from its 244 original form, which contains a 16 residue presignal and 5 residue activation peptide.
Kunitz soybean trypsin inhibitor is a type of protein contained in legume seeds which functions as a protease inhibitor. Kunitz-type Soybean Trypsin Inhibitors are usually specific for either trypsin or chymotrypsin. They are thought to protect seeds against consumption by animal predators.
Subtilases are a family of subtilisin-like serine proteases. They appear to have independently and convergently evolved an Asp/Ser/His catalytic triad, like in the trypsin serine proteases. The structure of proteins in this family shows that they have an alpha/beta fold containing a 7-stranded parallel beta sheet.
Protease, serine, 3 is a protein that in humans is encoded by the PRSS3 gene.
The PA clan is the largest group of proteases with common ancestry as identified by structural homology. Members have a chymotrypsin-like fold and similar proteolysis mechanisms but can have identity of <10%. The clan contains both cysteine and serine proteases. PA clan proteases can be found in plants, animals, fungi, eubacteria, archaea and viruses.
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