title: Purification of Cu/Zn superoxide dismutase from Piper betle leaf and its characterization in the oral cavity.
abstract: The aim of this study was to purify protein(s) from Piper betle leaf for identification and further characterization. A functionally unknown protein was purified to apparent homogeneity with a molecular mass of 15.7 kDa and identified as Cu/Zn superoxide dismutase (SOD). The purified SOD appeared to be monomeric and converted to its dimeric form with increased enzymatic activity in betel nut oral extract. This irreversible conversion was mainly induced by slaked lime, resulting from the increase in pH of the oral cavity. Oral extract from chewing areca nut alone also induced SOD dimerization due to the presence of arginine. The enhanced activity of the SOD dimer was responsible for the continuous production of hydrogen peroxide in the oral cavity. Thus, SOD may contribute to oral carcinogenesis through the continuous formation of hydrogen peroxide in the oral cavity, in spite of its protective role against cancer in vivo.
authors: Proteomics Core Lab, Department of Medical Research, China Medical University Hospital , No. 2 Yu-De Road, Taichung, 40407, Taiwan R.O.C.
authors: Yu-Ching
authors: YC
authors: Liu
authors: Miau-Rong
authors: MR
authors: Lee
authors: Chao-Jung
authors: CJ
authors: Chen
authors: Yung-Chang
authors: YC
authors: Lin
authors: Heng-Chien
authors: HC
authors: Ho
mesh_terms: D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008409:Mastication; D009055:Mouth / Q000737:chemistry / Q000378:metabolism*; D031721:Piper betle / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000737:chemistry / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D013482:Superoxide Dismutase / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase
keywords: Piper betle leaf; areca nut; arginine; dimerization; hydrogen peroxide; superoxide dismutase