The GMP protein content from dough decreased drastically and significantly when TG was added to 0.5%, although a lower dose increased the GMP content (Table 1). TG induced cross-linking into gluten proteins, but these new bonds caused structural changes in proteins, modifying their SDS solubility (Steffolani et al., 2008). TG catalyzes the formation of isopeptide bonds as well as the deami- dation of glutamine residues where water molecules are used as acyl acceptors (Motoki and Seguro, 1998). This reaction occurs mainly when glutamine residues are predominant over lysine residues such as in gluten proteins. Glutamine is transformed to glutamic acid by increasing negative charge density; the increase of repulsive interactions among protein chains prevents a stable aggregation (Weegels et al., 1990) and this promotes an increase of
Table 2