Polyphenol oxidase (PPO) was purified from peach pulp by a three-step column chromatographic procedure. The kinetics properties of the PPO fractions obtained from different purification steps were compared. All the fractions showed high affinities for (+)-catechin and (-)-epicatechin. The optimum pHs and optimum temperatures for all the fractions were the same. However, the fraction that contained pectin was more sensitive to the change of pH, and it had a lower affinity for the substrates and a higher thermostability than the fractions without pectin. In addition, the protein impurities in PPO fractions might have no effect on the properties of PPO. l-Cysteine and glutathione were effective for the inhibition of all the PPO fractions, while NaF inhibited moderately. However, the pectin could reduce the inhibition effects of those inhibitors.
Keywords: (+)-Catechin (PubChem CID: 9064); (−)-Epicatechin (PubChem CID: 72276); Catechol (PubChem CID: 289); Glutathione (PubChem CID: 124886); Kinetics; NaF (PubChem CID: 5235); Peach; Pectin; Polyphenol oxidase; Purification; l-Cysteine (PubChem CID: 5862).
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