Deamidation of Several Food Proteins Using Free and Immobilized Ca(2 +)-Independent Microbial Transglutaminase

Enzymatic deamidation of αsl-casein was done by using Ca(2 +)-independent microbial transglutaminase (MTGase) of a variant of Streptoverticillium mobaraense. Although the amount of deamidated glutamine residues in αsl -casein was not as high as that of the case using guinea pig liver transglutaminase (GTGase), the improvements in pH-solubility and Ca(2 +)-sensitivity profile of the substrate protein were comparable to it. To do the enzymatic deamidation without chemical acylation of Lys residues of αsl- casein, several immobilized MTGase were prepared with two types of chitosan beads. Although neither αsl-casein nor β-casein was deamidated, dimethyl casein and citraconylated soy 7S globulin were deamidated by using the immobilized enzymes.