| Abstract
| - The kinetics of the activation process of latent peach PPO by trypsin was studied. By coupling thisactivation process to the oxidation of 4-tert-butylcatechol (TBC) to its corresponding quinone, itwas possible to evaluate the specific rate constant of active PPO formation, k3, which showed avalue of 0.04 s-1. This proteolytic activation of latent peach PPO permitted us to characterize themonophenolase activity of peach PPO for the first time using p-cresol as substrate, and it showedthe characteristic lag period of the kinetic mechanism of monophenols hydroxylation, which dependedon the enzyme and substrate concentration, the pH and the presence of catalytic amounts ofo-diphenol (4-methylcatechol). The enzyme activation constant, kact, was 2 μM. Keywords: Latent PPO; trypsin; peach; monophenolase activity
|
