Characterization, purification, and temperature/pressure stability of polyphenol oxidase extracted from plums (Prunus domestica)

In this study, polyphenol oxidase (PPO) was extracted from Prunus domestica and partially purified by ammonium sulfate precipitation, hydrophobic interaction chromatography, and ion exchange chromatography. The final purification step revealed a 32.81-fold purification, and the molecular mass was estimated to be 65 kDa by SDS-PAGE. The purified PPO showed enzymatic activity mainly toward five substrates, namely catechol, catechin, 4-methyl catechol, chlorogenic acid, and L-3,4-dihydroxyphenylalanine, whereas it showed no activity toward caffeic acid, ferulic acid, p-coumaric acid, p-cresol, and L-tyrosine. The optimum pH and temperature values were 6.0 and 25 degrees C, respectively. The enzyme showed high stability in the pH range of 5.0-7.0 and in the temperature range of 25-65 degrees C. The most effective inhibitors of this enzyme were found to be ascorbic acid and L-cysteine. The thermal inactivation followed a first-order kinetic model, with activation energy of E-a 150.46 +/- 1.29 kJ/mol. PPO extracted from plum showed stability at high pressure, with enzyme activation at 500 MPa. (C) 2017 Elsevier Ltd. All rights reserved.