Transglutaminase
Encyclopedia
Transglutaminases are a family of enzymes  that catalyze the formation of a covalent bond
Covalent bond
A covalent bond is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms. The stable balance of attractive and repulsive forces between atoms when they share electrons is known as covalent bonding....

 between a free amine
Amine
Amines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...

 group (e.g., protein- or peptide-bound lysine) and the gamma-carboxamid group of protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

- or peptide
Peptide
Peptides are short polymers of amino acid monomers linked by peptide bonds. They are distinguished from proteins on the basis of size, typically containing less than 50 monomer units. The shortest peptides are dipeptides, consisting of two amino acids joined by a single peptide bond...

-bound glutamine
Glutamine
Glutamine is one of the 20 amino acids encoded by the standard genetic code. It is not recognized as an essential amino acid but may become conditionally essential in certain situations, including intensive athletic training or certain gastrointestinal disorders...

. Bonds formed by transglutaminase exhibit high resistance to proteolytic degradation
Proteolysis
Proteolysis is the directed degradation of proteins by cellular enzymes called proteases or by intramolecular digestion.-Purposes:Proteolysis is used by the cell for several purposes...

.

Transglutaminases were first described in 1959. The exact biochemical activity of transglutaminases was discovered in blood coagulation
Coagulation
Coagulation is a complex process by which blood forms clots. It is an important part of hemostasis, the cessation of blood loss from a damaged vessel, wherein a damaged blood vessel wall is covered by a platelet and fibrin-containing clot to stop bleeding and begin repair of the damaged vessel...

 protein factor XIII
Factor XIII
Factor XIII or fibrin stabilizing factor is an enzyme of the blood coagulation system that crosslinks fibrin.- Function :Factor XIII is a transglutaminase that circulates in the plasma as a heterotetramer of two catalytic A subunits and two carrier B subunits...

 in 1968.

Physiological transglutaminases

Eight transglutaminases have been characterised.
Name Gene Activity Chromosome
Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...

 
OMIM
Mendelian Inheritance in Man
Online Mendelian Inheritance in Man is a database that catalogues all the known diseases with a genetic component, and—when possible—links them to the relevant genes in the human genome and provides references for further research and tools for genomic analysis of a catalogued gene. OMIM is one...

Factor XIII
Factor XIII
Factor XIII or fibrin stabilizing factor is an enzyme of the blood coagulation system that crosslinks fibrin.- Function :Factor XIII is a transglutaminase that circulates in the plasma as a heterotetramer of two catalytic A subunits and two carrier B subunits...

 (fibrin-stabilizing factor)
F13A1
F13A1
Coagulation factor XIII A chain is a protein that in humans is encoded by the F13A1 gene.-Interactions:Coagulation factor XIII, A1 polypeptide has been shown to interact with F13B.-Further reading:...

, F13B
F13B
Coagulation factor XIII B chain is a protein that in humans is encoded by the F13B gene.-Interactions:F13B has been shown to interact with Coagulation factor XIII, A1 polypeptide.-Further reading:...

 
coagulation 6p25-p24
Keratinocyte transglutaminase
Keratinocyte transglutaminase
Protein-glutamine gamma-glutamyltransferase K is an enzyme that in humans is encoded by the TGM1 gene.Keratinocyte transglutaminase is a transglutaminase enzyme.-Pathology:...

 
TGM1  skin 14q11.2
Tissue transglutaminase
Tissue transglutaminase
Tissue transglutaminase is an enzyme of the transglutaminase family. Like other transglutaminases, it crosslinks proteins between an ε-amino group of a lysine residue and a γ-carboxamide group of glutamine residue, creating an inter- or intramolecular bond that is highly resistant to proteolysis...

 
TGM2  ubiquitous 20q11.2-q12
Epidermal transglutaminase  TGM3
TGM3
For the Tetris game, see Tetris: The Grand Master.Protein-glutamine gamma-glutamyltransferase E is an enzyme that in humans is encoded by the TGM3 gene.-Further reading:...

 
skin 20q12
Prostate transglutaminase  TGM4
TGM4
Protein-glutamine gamma-glutamyltransferase 4 is an enzyme that in humans is encoded by the TGM4 gene.-Further reading:...

 
prostate 3p22-p21.33
TGM X TGM5
TGM5
TGM5 is a transglutaminase enzyme.TGM5 encodes one member of a the multigene transglutaminase family. Transglutaminases are involved in protein cross-linking by catalyzing the formation of gamma-glutamyl-lysine isodipeptide bonds between adjacent polypeptides...

 
skin 15q15.2
TGM Y TGM6  unclear 20q11-15 not assigned
TGM Z TGM7  testis, lung 15q15.2

Mechanism of action

Transglutaminases form extensively cross-linked, generally insoluble protein polymers. These biological polymers are indispensable for the organism to create barriers and stable structures. Examples are blood clots (coagulation factor XIII
Factor XIII
Factor XIII or fibrin stabilizing factor is an enzyme of the blood coagulation system that crosslinks fibrin.- Function :Factor XIII is a transglutaminase that circulates in the plasma as a heterotetramer of two catalytic A subunits and two carrier B subunits...

), as well as skin
Skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...

 and hair
Hair
Hair is a filamentous biomaterial, that grows from follicles found in the dermis. Found exclusively in mammals, hair is one of the defining characteristics of the mammalian class....

.

The catalytic reaction is generally viewed as being irreversible, and must be closely monitored through extensive control mechanisms. A collection of the transglutaminase substrate proteins and interaction partners is accessible in the TRANSDAB database.

Role in disease

Deficiency of factor XIII (a rare genetic condition) predisposes to hemorrhage; concentrated enzyme can be used to correct the abnormality and reduce bleeding risk.

Antibodies
Antibody
An antibody, also known as an immunoglobulin, is a large Y-shaped protein used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. The antibody recognizes a unique part of the foreign target, termed an antigen...

 to tissue transglutaminase are found in celiac disease and may play a role in the small bowel damage in response to dietary gliadin
Gliadin
Gliadin is a glycoprotein present in wheat and several other cereals within the grass genus Triticum. Gliadins are prolamins and are separated on the basis of electrophoretic mobility and isoelectric focusing.- Types :...

 that characterises this condition. In the related condition dermatitis herpetiformis
Dermatitis herpetiformis
Dermatitis herpetiformis , or Duhring's disease,Freedberg, et al. . Fitzpatrick's Dermatology in General Medicine. . McGraw-Hill. ISBN 0-07-138076-0. is a chronic blistering skin condition, characterised by blisters filled with a watery fluid...

, in which small bowel changes are often found and which responds to dietary exclusion of gliadin-containing wheat products, epidermal transglutaminase is the predominant autoantigen.

Recent research indicates that sufferers from neurological diseases like Huntington
Huntington's disease
Huntington's disease, chorea, or disorder , is a neurodegenerative genetic disorder that affects muscle coordination and leads to cognitive decline and dementia. It typically becomes noticeable in middle age. HD is the most common genetic cause of abnormal involuntary writhing movements called chorea...

's, and Parkinson's
Parkinson's disease
Parkinson's disease is a degenerative disorder of the central nervous system...

 may have unusually high levels of one type of transglutaminase, tissue transglutaminase
Tissue transglutaminase
Tissue transglutaminase is an enzyme of the transglutaminase family. Like other transglutaminases, it crosslinks proteins between an ε-amino group of a lysine residue and a γ-carboxamide group of glutamine residue, creating an inter- or intramolecular bond that is highly resistant to proteolysis...

. It is hypothesized that tissue transglutaminase may be involved in the formation of the protein aggregates that causes Huntington's disease, although it is most likely not required.

Mutations in keratinocyte transglutaminase
Keratinocyte transglutaminase
Protein-glutamine gamma-glutamyltransferase K is an enzyme that in humans is encoded by the TGM1 gene.Keratinocyte transglutaminase is a transglutaminase enzyme.-Pathology:...

 are implicated in lamellar ichthyosis.

Industrial and culinary applications

In commercial food processing, transglutaminase is used to bond proteins together. Examples of foods made using transglutaminase include imitation crabmeat, and fish ball
Fish ball
Fish balls are a common food in southern China and overseas Chinese communities made from surimi . They are also common in Scandinavia, where they are usually made from cod or haddock.-Terminology:...

s. It is produced by Streptoverticillium mobaraense fermentation
Industrial fermentation
Industrial fermentation is the intentional use of fermentation by microorganisms such as bacteria and fungi to make products useful to humans. Fermented products have applications as food as well as in general industry.- Food fermentation :...

 in commercial quantities or extracted from animal blood, and is used in a variety of processes, including the production of processed meat
Meat
Meat is animal flesh that is used as food. Most often, this means the skeletal muscle and associated fat and other tissues, but it may also describe other edible tissues such as organs and offal...

 and fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

 products.

Transglutaminase can be used as a binding agent to improve the texture of protein-rich foods such as surimi
Surimi
Surimi is a Japanese loan word referring to a fish-based food product that has been pulverized to a thick paste and has the property of a dense and rubbery food item when cooked...

 or ham
Ham
Ham is a cut of meat from the thigh of the hind leg of certain animals, especiallypigs. Nearly all hams sold today are fully cooked or cured.-Etymology:...

.

Transglutaminase can be used in these applications:
  • Improving texture of emulsified meat products, such as sausage
    Sausage
    A sausage is a food usually made from ground meat , mixed with salt, herbs, and other spices, although vegetarian sausages are available. The word sausage is derived from Old French saussiche, from the Latin word salsus, meaning salted.Typically, a sausage is formed in a casing traditionally made...

    s and hot dog
    Hot dog
    A hot dog is a sausage served in a sliced bun. It is very often garnished with mustard, ketchup, onions, mayonnaise, relish and/or sauerkraut.-History:...

    s.
  • Binding different meat parts into a larger ones ("portion control"), such as in restructured steak
    Restructured steak
    Restructured steak is a catch-all term to describe a class of beef steaks made from smaller pieces of beef fused together by a binding agent. Its development started from the 1970s. Allowed food-grade agents include:...

    s. Transglutaminase is one of several forms of "meat glue".
  • Improving the texture of low-grade meat such as so-called "PSE meat
    PSE meat
    Pale, soft, exudative meat or PSE meat or PSE pork is pork generally regarded as being of inferior quality, characterised by its pallor, softness and low water binding capacity. It is more common in pigs sensitive to the anaesthetic halothane. In most cases it appears to be the result of...

    " (pale, soft, and exudative meat, whose characteristics are attributed to stress and a rapid postmortem pH
    PH
    In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...

     decline)
  • Making milk
    Milk
    Milk is a white liquid produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals before they are able to digest other types of food. Early-lactation milk contains colostrum, which carries the mother's antibodies to the baby and can reduce the risk of many...

     and yogurt creamier
  • Making noodles firmer

Molecular gastronomy

Transglutaminase is also used in molecular gastronomy
Molecular gastronomy
Molecular gastronomy is a subdiscipline of food science that seeks to investigate, explain and make practical use of the physical and chemical transformations of ingredients that occur while cooking, as well as the social, artistic and technical components of culinary and gastronomic phenomena in...

 to meld new textures with existing tastes. Besides these mainstream uses, transglutaminase has been used to create some unusual foods. British chef Heston Blumenthal
Heston Blumenthal
Heston Marc Blumenthal OBE is an English chef and owner of The Fat Duck, a three-Michelin-starred restaurant in Bray, Berkshire voted Best Restaurant in the UK by The Good Food Guide 2007 and 2009, and voted best restaurant in the world by Restaurant magazine in 2005...

 is credited with the introduction of transglutaminase into modern cooking.

Wylie Dufresne
Wylie Dufresne
Wylie Dufresne is the chef and owner of wd~50 restaurant in Manhattan. Dufresne is a leading American proponent of molecular gastronomy, the movement to incorporate science and new techniques in the preparation and presentation of food.-Early life:...

, chef
Chef
A chef is a person who cooks professionally for other people. Although over time the term has come to describe any person who cooks for a living, traditionally it refers to a highly skilled professional who is proficient in all aspects of food preparation.-Etymology:The word "chef" is borrowed ...

 of New York's avant-garde
Avant-garde
Avant-garde means "advance guard" or "vanguard". The adjective form is used in English to refer to people or works that are experimental or innovative, particularly with respect to art, culture, and politics....

 restaurant wd~50, was introduced to transglutaminase by Blumenthal, and invented a "pasta
Pasta
Pasta is a staple food of traditional Italian cuisine, now of worldwide renown. It takes the form of unleavened dough, made in Italy, mostly of durum wheat , water and sometimes eggs. Pasta comes in a variety of different shapes that serve for both decoration and to act as a carrier for the...

" made from over 95% shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...

thanks to transglutaminase.
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