Deamidation of Several Food Proteins Using Free and Immobilized Ca²⁺-Independent Microbial Transglutaminase

Abstract

Enzymatic deamidation of α_s1-casein was done by using Ca²⁺-independent microbial transglutaminase (MTGase) of a variant of Streptoverticillium mobaraense. Although the amount of deamidated glutamine residues in α_s1-casein was not as high as that of the case using guinea pig liver transglutaminase (GTGase), the improvements in pH-solubility and Ca²⁺-sensitivity protile of the substrate protein were comparable to it. To do the enzymatic deamidation without chemical acylation of Lys residues of α_s1-casein, several immobilized MTGase were prepared with two types of chitosan beads. Although neither α^s1-casein nor β-casein was deamidated, dimethyl casein and citraconylated soy 7S globulin were deamidated by using the immobilized enzymes.