Selenoprotein P in human plasma as an extracellular phospholipid hydroperoxide glutathione peroxidase: Isolation and enzymatic characterization of human selenoprotein P

Yoshiro Saito, Takaaki Hayashi, Ayako Tanaka, Yasuko Watanabe, Masayo Suzuki, Eiji Saito, Kazuhiko Takahashi

研究成果: Article査読

216 被引用数 (Scopus)

抄録

Selenoprotein P is an extracellular protein containing presumably 10 selenocysteines that are encoded by the UGA stop codon in the open reading frame of the mRNA. The function of selenoprotein P is currently unknown, although several indirect lines of evidence suggest that selenoprotein P is a free radical scavenger. We first developed a conventional procedure to isolate selenoprotein P from human plasma. Next, we investigated the reactivities of selenoprotein P against various hydroperoxides in the presence of glutathione. Although selenoprotein P reduces neither hydrogen peroxide nor tertiary butyl hydroperoxide, it does reduce phospholipid hydroperoxide such as 1-palmitoyl-2-(13-hydroperoxy-cis-9,trans-11- octadecadienoyl)-3-phosphatidylcholine hydroperoxide. Kinetic analysis demonstrated a tert-uni ping-pong mechanism, similar to those described for classical glutathione peroxidase and phospholipid hydroperoxide glutathione peroxidase. Not only glutathione, but also dithiothreitol, mercaptoethanol, cysteine, and homocysteine, were effective as reducing substances, as in the case of phospholipid hydroperoxide glutathione peroxidase. These results show that selenoprotein P functions as a phospholipid hydroperoxide glutathione peroxidase in extracellular fluids.

本文言語English
ページ(範囲)2866-2871
ページ数6
ジャーナルJournal of Biological Chemistry
274
5
DOI
出版ステータスPublished - 1999 1月 29
外部発表はい

ASJC Scopus subject areas

  • 生化学
  • 分子生物学
  • 細胞生物学

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