title: Purification and kinetic characterization of polyphenol oxidase from Barbados cherry (Malpighia glabra L.).
abstract: Polyphenol oxidase (PPO) of Barbados cherry was extracted and purified through ammonium sulfate precipitation, gel filtration, and affinity chromatography. The purification factor for PPO was 60% with 8.3% yield. The enzyme was characterized for thermal stability, pH and kinetic parameters. The molecular mass of PPO was approximately the sum of 52 and 38kDa estimated by SDS-PAGE. The purity was checked by native PAGE, showing a single prominent band. The optimum pH was 7.2. The enzyme had a temperature optimum at 40°C and was relatively stable at 60°C, with 55% loss of activity. Sodium diethyl dithiocarbamate (SDDC), l-cysteine and ascorbate significantly inhibited PPO activity. 4-Methyl catechol and catechol were found to be efficient diphenolic substrates for cherry PPO, considering the Vmax/Km ratio. The data obtained in this study may help to understand cherry fruit browning.
authors.affiliation: Plant Biochemistry and Molecular Biology Laboratory, Department of Botany, University College, Thiruvananthapuram 695 034, Kerala, India.
authors.forename: V B Anil
authors.initials: VB
authors.lastname: Kumar
authors.affiliation: Plant Biochemistry and Molecular Biology Laboratory, Department of Botany, University College, Thiruvananthapuram 695 034, Kerala, India.
authors.forename: T C Kishor
authors.initials: TC
authors.lastname: Mohan
authors.affiliation: Plant Biochemistry and Molecular Biology Laboratory, Department of Botany, University College, Thiruvananthapuram 695 034, Kerala, India. Electronic address: harimurukan@gmail.com.
authors.forename: K
authors.initials: K
authors.lastname: Murugan
keywords: Affinity chromatography; Barbados cherry; Browning; Inhibition; Kinetics; Polyphenol oxidase