The isothermal pressure inactivation of microbial transglutaminase in 0.2 M tris-acetate buffer (pH 6.0) was studied at 20, 40 and 60 degreesC. The inactivation kinetics followed a first order kinetic model. With increasing pressure at constant temperature, a consistent increase in inactivation rate constants k was noted, pointing to a negative activation volume DeltaV*. The values of DeltaV* were calculated as -7.1 cm(3)/mol at 20 degreesC, -17.4 cm(3)/mol at 40 degreesC and -2.3 cm(3)/mol at 60 degreesC, indicating a reduced pressure sensitivity at high temperature. A casein-based system was used to prove that transglutaminase is capable of cross-linking protein under high pressure, indicating that the enzyme can be used in combination with high pressure treatment of food.