Transglutaminase
- CAS Number: 80146-85-6
Transglutaminases (more precisely, protein - glutamine γ - Glutamyltransferasen ) are enzymes that cross-links can manufacture within or between proteins, whereby the properties of the substrate are greatly changed. An example is the bonding of fibrin in blood coagulation by Factor XIII. Transglutaminases are found in all eukaryotes, are known in humans, eight such enzymes whose function is adjacent to the coagulation of blood in the stabilization of different structural proteins. Mutations that lead to genetic diseases are known by F13A1, EPB42, TGM1 and TGM5.
Most known transglutaminases from higher organisms are calcium - dependent, but in addition are also calcium - independent bacterial transglutaminases (eg Streptomyces mobaraensis ) are known which have no common root with eukaryotic transglutaminases.
Catalyzed reaction
Transglutaminase catalyzes the acyl transfer of protein-bound glutamine residues to primary amines. Is in the reaction in addition to the γ - glutamyl group of the amino acid glutamine and the ε -amino function of a lysine residue involved, there is an intra - or intermolecular linking of proteins by the formation of an isopeptide bond.
In the active site of transglutaminase is a reactive cysteine residue (E -SH ). The reaction is divided into two steps, which are released in the first step with the formation of the acyl - enzyme complex ammonium ions. The second step is to release the enzyme is transferring to primary amines. The isopeptide bond formed is very stable from a biochemical point of view, since it can not be enzymatically cleaved by proteases.
Medicine
The tissue transglutaminase ( Transglutaminase2, TG2 ) has gained outstanding importance for the diagnosis of celiac disease. This food intolerance to cereal proteins leads to the formation of auto-antibodies against the body's own tissue transglutaminase. Of autoantibodies ( anti- TG2 IgA antibody) is considered the major autoantigen. He is the most important chemical laboratory screening test (next to the Endomysiumantikörper (EMA ) IgA type ). He has negative predictive value of almost 100 % and a positive predictive value of 72%.
Application as meat glue
An industrial application of transglutaminase cross-linking of proteins in sausages and " restrukturiertem " meat ( processed meat ) and fish and dairy products. For industrial use transglutaminase is obtained from Streptomyces mobaraensis.
"Just a transglutaminase preparation is currently available on the European market. The enzyme is mobaraense ( syn.: mobaraensis ) using the conventional bacterium Streptoverticillium won ". .