Incorporation of Amino Acids into Food Proteins by Transglutaminase

Abstract

Transglutaminase catalyzes the formation of ε-(ν-glutamyl)lysine crosslinks and the substitution of a variety of primary amines for the ν-carboxamide groups of protein-bound glutaminyl residues. This study examined the feasibility of the use of the transglutaminase reaction for fortifying food proteins by the covalent attachment of limiting essential amino acids.
In the reactions using L-methionine ethyl ester as a substrate, the methionine content of α_s1 and β-caseins, and soybean 7S and 11S proteins increased to 200, 150, 240 and 350% of the starting materials, respectively. With wheat gluten, incorporation of L-lysine was tested and a 5.1-fold increase in lysine content was observed. These results suggest that transglutaminase could be a useful tool for improving the amino acid composition of food proteins.