title: Purification and structural analysis of membrane-bound polyphenol oxidase from Fuji apple.
abstract: Membrane-bound polyphenol oxidase (mPPO) in Fuji apple (Malus domestica Borkh. cv. Red Fuji) was purified and analyzed with a nanoelectrospray ionization mass spectrometer. The three-dimensional model and binding site of mPPO to 4-methyl catechol were also studied using molecular docking. mPPO was purified 54.41-fold using temperature-induced phase partitioning technique and ion exchange chromatography. mPPO had a molecular weight of 67.3kDa. Even though a significant level of homology was observed between mPPO and the soluble polyphenol oxidase in the copper binding sequence, there was another region, rich in histidine residues, which differed in 13 amino acids. The three-dimensional structure of mPPO consisted of six α-helices, two short β-strands, and ten random coils. The putative substrate-binding pocket contained six polar or charged amino acids, His191, His221, Trp224, Trp228, Phe227, and Val190. Trp224 and Trp228 formed hydrogen bonds with 4-methyl-catechol.
authors: College of Food Science and Nutritional Engineering, China Agricultural University, No. 17 Qinghua East Road, Beijing 100083, China.
authors: Fang
authors: F
authors: Liu
authors: College of Food Science and Nutritional Engineering, China Agricultural University, No. 17 Qinghua East Road, Beijing 100083, China.
authors: Jin-Hong
authors: JH
authors: Zhao
authors: College of Food Science and Nutritional Engineering, China Agricultural University, No. 17 Qinghua East Road, Beijing 100083, China.
authors: Xin
authors: X
authors: Wen
authors: College of Food Science and Nutritional Engineering, China Agricultural University, No. 17 Qinghua East Road, Beijing 100083, China. Electronic address: niyycau@hotmail.com.
authors: Yuan-Ying
authors: YY
authors: Ni
mesh_terms: D001665:Binding Sites; D004156:Catechol Oxidase / Q000737:chemistry*; D005503:Food Additives / Q000032:analysis; D005638:Fruit / Q000737:chemistry*; D027845:Malus / Q000737:chemistry*; D062105:Molecular Docking Simulation
chemical_list: D005503:Food Additives; D004156:Catechol Oxidase
keywords: Binding site; Fuji apple; Molecular docking; Polyphenol oxidase; Purification