By definition[31], TGases, including the well-characterized guinea pig liver enzyme, require Ca2+ for expression of enzymatic activity. However, MTGase from a variant of Streptoverticillium mobaraense is totally independent of Ca2+. In this aspect, MTGase is quite unique from other mammalian enzymes. Such a property is very useful in the modification of functional properties of food proteins, because many food proteins, such as milk caseins, soybean globulins and myosins, are susceptible to Ca2+. They are easily precipitated in the presence of Ca2+ and become less sensitive to MTGase.