Binding of α‐tocopherylquinone, an oxidized form of α‐tocopherol, to glutathione‐S‐transferase in the liver cytosol

FEBS Letters

Arita, Makoto¹  Sato, Yuji¹  Arai, Hiroyuki¹  Inoue, Keizo¹ 

[1] Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan

关键词: α-Tocopherol;    Antioxidant;    α-Tocopherylquinone;    Binding protein;    Glutathione-S-transferase;    Rat liver;    αTTP;    α-tocopherol transfer protein;    GST;    glutathione-S-transferase;   

DOI  :  10.1016/S0014-5793(98)01176-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

α-Tocopherol (vitamin E) is an important fat-soluble antioxidant in biological systems and, as a result of scavenging reactive oxygen, it is converted to α-tocopherylquinone. α-Tocopherol binds to α-tocopherol transfer protein (αTTP) in the liver cytosol, whereas α-tocopherylquinone does not. We found that α-tocopherylquinone binds to a liver protein with a molecular mass of about 40 kDa that is distinct from αTTP. This α-tocopherylquinone binding protein was purified further by multiple-step column chromatography. Sodium dodecylsulfate-polyacrylamide gel electrophoresis of the final preparation yielded a single band with an apparent molecular mass of 25 kDa, which microsequencing revealed was identical to glutathione-S-transferase (GST). The GST activity was inhibited in the presence of α-tocopherylquinone, as it is by other non-substrate ligands for GST, confirming that GST and α-tocopherylquinone interact directly. α-Tocopherylquinone binds to GST and may be transported to the site of metabolism or excreted in the bile as other non-substrate ligands for GST.

【 授权许可】

Unknown