Transglutaminase Protein Substrates of Food Interest

Transglutaminases (TGase, EC 2.3.2.13) are a widely distributed group of enzymes that crosslink proteins through an acyl transfer reaction resulting in a ε-(γ-glutamyl)lysine isopeptide bond. The number of proteins acting as TGase substrate is restricted, since both protein’s primary structure and conformation determine whether a glutamine or lysine residue can be reactive. The interest towards these enzymes is stimulated by their involvement in a growing number of human diseases such as celiac disease. Among the TGase isoforms, the microbial one (mTGase) has been object of special attention in the food sector, because of its calcium independency and its broad substrate specificity for the acyl donor. In fact, it was used to strengthen the texture of homogenized sausages made of pork, beef, or poultry meat, to increase the hardness of fishes, to improve the quality of different dairy products, as well as to enhance the elasticity of candies. In addition, the mTGase-catalysed modification of wheat flour proteins increases the elasticity and resilience of dough as well as the volume of bread. The purpose of this chapter is to present an overview of the literature focused on the ability of plant and animal proteins of food interest to act as mTGase substrates.