title: Purification and partial characterization of polyphenol oxidase from the flower buds of Lonicera japonica Thunb.
abstract: The purification and partial enzymology characteristics of polyphenol oxidase from Lonicera japonica (LjPPO) were studied in this paper. The crude enzyme solution was purified in turn by ammonium sulfate, dialysis, and DEAE-cellulose ion-exchange chromatography after preliminary treatments. Purification resulted in 31-fold enrichment and its molecular weight was estimated to be ~49 kDa exhibited on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The pH for optimal conditions of LjPPO was 7.5, and the temperature was 25 °C, in addition, the inhibitive effects of inhibitors were enhanced positively with increasing of the concentration. Moreover, crude enzyme solution showed diphenolase activity toward catechol, l-dopa and chlorogenic acid rather than monophenolase and triphenolase activity, and the best substrate was catechol because of the highest V(max)/K(m) value. However, the oxidation of diphenol related to browning significantly, so the data obtained in this research provided theoretical basis for the prevention of enzymatic browning of L. japonica during processing.
authors.affiliation: Shandong Analysis and Test Center, Shandong Academy of Sciences, 19 Keyuan Street, Jinan, Shandong 250014, China.
authors.forename: Na-na
authors.initials: NN
authors.lastname: Liu
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.forename: Dai-jie
authors.initials: DJ
authors.lastname: Wang
authors.forename: Yi-bin
authors.initials: YB
authors.lastname: Zhou
authors.forename: Xiao-jing
authors.initials: XJ
authors.lastname: Lin
authors.forename: Xiao
authors.initials: X
authors.lastname: Wang
authors.forename: Sheng-bo
authors.initials: SB
authors.lastname: Li
mesh_terms: D004156:Catechol Oxidase / Q000737:chemistry* / Q000302:isolation & purification* / Q000378:metabolism; D004795:Enzyme Stability; D035264:Flowers / Q000201:enzymology / Q000254:growth & development; D007700:Kinetics; D031239:Lonicera / Q000737:chemistry / Q000201:enzymology*; D008970:Molecular Weight; D010940:Plant Proteins / Q000737:chemistry* / Q000302:isolation & purification* / Q000378:metabolism; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D010940:Plant Proteins; D004156:Catechol Oxidase