Incorporation of Lysine- and Lysine Dipeptides into α_s1-Casein by Ca²⁺-independent Microbial Transglutaminase

Abstract

Ca²⁺-independent microbial transglutaminase of a variant of Streptoverticillium mobaraense was compared with Ca²⁺-dependent guinea pig liver transglutaminase as a tool for incorporating lysine or lysine dipeptides into a food protein. The microbial enzyme was able to incorporate up to ca. 12 mol lrsine into a mole of citra-conylated α_s1-casein. Twenty two lysine dipeptides could be the substrate for incorporation catalyzed by the enzyme. The microbial enzyme showed much higher incorporation of lysine or lysine dipeptides than the guinea pig liver enzyme, which was attributed to the higher themostability of the microbial enzyme.