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KMID : 0380220070400030412
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Journal of Biochemistry and Molecular Biology
2007 Volume.40 No. 3 p.412 ~ p.418
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Purification and Physicochemical Characterization of a Recombinant Phospholipid Hydroperoxide Glutathione Peroxidase from Oryza sativa
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Wang Zebin
Wang Feng
Duan Rui
Liu Jin-Yuan
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Abstract
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Phospholipid hydroperoxide glutathione peroxidase (PHGPx) is an unique antioxidant enzyme that directly reduces lipid hydroperoxides in biomembranes. In the present work, the entire encoding region for Oryza sativa PHGPx was expressed in Escherichia coli M15, and the purified fusion protein showed a single band with 21.0 kD and pI = 8.5 on SDS- and IFE-PAGE, respectively. Judging from CD and fluorescence spectroscopy, this protein is considered to have a well-ordered structure with 12.2% &agr;-helix, 30.7% &bgr;-sheet, 18.5% &ggr;-turn, and 38.5% random coil. The optimum pH and temperature of the enzyme activity were pH 9.3 and 27°C. The enzyme exhibited the highest affinity and catalytical efficiency to phospholipid hydroperoxide employing GSH or Trx as electron donor. Moreover, the protein displayed higher GSH-dependent activity towards t-Butyl-OOH and H2O2. These results show that OsPHGPx is an enzyme with broad specificity for hydroperoxide substrates and yielded significant insight into the physicochemical properties and the dynamics of OsPHGPx.
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KEYWORD
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Oryza sativa, Phospholipid hydroperoxide glutathione peroxidase, Purification, Physicochemical characterization, Enzyme activity
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