Tissue transglutaminase function

An alternative to modifying the functional group attached to fibrils is to utilise the chemistry present in the amino acid side chains. Furthermore, as peptides often undergo specific modification by enzymes in vivo, these could be harnessed for synthetic purposes. Qll (Ac-QQKFQFQFEQQ-Am, a fibril-forming peptide based on Pi 1-2), was coupled to lysine-based molecules by treatment with an enzyme (tissue transglutaminase, TGase) which results in a reaction between lysine and glutamine side chains [72] (Fig. 32). 

Seissler J, Wohlrab U, Wuensche C, Scherbaum WA, Boehm BO. Autoantibodies from patients with coeliac disease recognize distinct functional domains of the autoantigen tissue transglutaminase. Clin Exp Immunol 2001 125 216-221. 

In vitro, the enzyme is able to catalyze crosslinking of whey proteins, soy proteins, wheat proteins, beef myosin, casein and crude actomyosin (which is refined from mechanically deboned meat), leading to their texturization [74, 117]. This capacity of the enzyme has been used in attempts to improve the functional properties of food. Until the end of the 1980s, commercial transglutaminase could only be obtained from animal tissues, most commonly from guinea pig liver. 

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