Kinetic characterization, thermal and pH inactivation study of peroxidase and pectin methylesterase from tomato (Solanum betaceum)

Abstract Peroxidase (POD) and pectin methylesterase (PME) from tomato were characterized, studied thermal stability, and analyzed the synergistic effect of temperature and pH. For POD, the optimal activity, using H2O2 as substrate and ABTS+• as the donor H+, was obtained at pH 3.5, and for PME, the optimal activity using pectin as substrate was obtained at pH 7.5. In POD, it was found that the values of KM, Vm and Ksi for H2O2 were 477.26 mM, 721.53 µM/min and 0.37 mM, respectively. In PME, the values of KM and Vm obtained for pectin were 0.54 mM and 436.12 µM/min, respectively. On the other hand, it was found that POD was inactivated with 90 °C, at pH from 2.5 to 3.5 with temperatures of 55 to 90 °C, and at pH of 2.5 to 3 with temperatures of 40 to 90 °C. Likewise, PME was inactivated at 90 °C, and at pH of 3.5 with 70 °C.