Transglutaminases are a family of enzymes that catalyze the posttranslational modification of proteins by inserting an isopeptide bond within or between polypeptide chains. These enzymes catalyze the acyl transfer reaction between the g-carboxyamide groups of peptide-bound glutamine residues and a variety of primary amines, particularly the e-amino group of lysine. The resulting crosslink is of great significance since it is highly stable and also resistant to mechanical and proteolytic degradation.