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 K_M, V_m and K_si for H₂O₂ were 477.26 mM, 721.53 µM/min and 0.37 mM, respectively. In PME, the values of K_M and V_m 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.

Keywords:
peroxidase; pectin methylesterase; kinetic parameters; thermal inactivation and pH inactivation