Abstract
BACKGROUND: This paper describes the modeling of the kinetics of thermal inactivation of transglutaminase (TGase) from a newly isolated Bacillus circulans BL32, isolated from the Amazon environment. The purified enzyme was incubated at temperatures ranging from 30 to 70 °C and values of the thermodynamic inactivation parameters, such as activation energy (Δ__E__), activation enthalpy (Δ__H__), activation entropy (Δ__S__), and free energy (Δ__G__) for thermal inactivation, were calculated.
RESULTS: The kinetics of TGase thermo‐inactivation followed a Lumry–Eyring model. The enzyme was very stable up to 50 °C, with approximately 50% of activity remaining after heating for 12 h. It was completely inactivated by incubation at 70 °C for 2 min. Δ__E__ for TGase was 350.5 kJ mol^−1^. Δ__H__ and Δ__S__ for thermo‐inactivation of the TGase were 347.8 kJ mol^−1^ and 744 J mol^−1^ K^−1^ at 50 °C, respectively. Dynamic light scattering measurements suggest that the thermal inactivation of this microbial TGase can be partially attributed to the formation of aggregates.
CONCLUSION: These results provide useful information about the thermal characteristics of the microbial TGase from B. circulans BL32 and indicate that this enzyme could be a good candidate for industrial applications. Copyright © 2009 Society of Chemical Industry