Transglutaminase

Transglutaminase refers to a family of enzymes that catalyze acyl transfer reactions between the gamma-carboxamide groups of glutamine residues and primary amines, forming epsilon-(gamma-glutamyl) lysine isopeptide bonds. This cross-linking strengthens and stabilizes protein networks in tissues and food products. In humans, several transglutaminases exist; the best studied is tissue transglutaminase (TG2), a Ca2+-dependent enzyme involved in extracellular matrix stabilization, wound healing, and cellular signaling. Other mammalian members participate in various tissues, sometimes with distinct substrate specificities.

A widely utilized form in industry is microbial transglutaminase (MTGase), produced by Streptomyces mobaraensis (formerly Streptoverticillium mobaraense). MTGase is calcium-independent and functions under a broad range of pH and temperatures, making it practical for food processing.

Applications and uses: MTGase is employed to create and improve protein networks in foods, enhancing texture, water-holding capacity, sliceability, and yield. In bakery, MTGase strengthens dough and crumb structure; in meat, dairy, and seafood products it acts as a binder and optimizer of mouthfeel; it is also used to improve texture in gluten-free products and refrigerated foods.

Safety and regulation: Transglutaminases are widely used processing aids in many countries, with regulatory status varying by jurisdiction. Tissue TG2 is also an endogenous human enzyme and an autoantigen of interest in celiac disease; the relevance of dietary MTGase-treated gluten to disease pathogenesis is a subject of research and regulatory review. As with other enzyme additives, labeling and exposure are subject to food safety oversight.