Selenite reduction by the thioredoxin system: Kinetics and identification of protein-bound selenide

Takashi Tamura, Kumi Sato, Kentaro Komori, Takeshi Imai, Mitsuhiko Kuwahara, Takahiro Okugochi, Hisaaki Mihara, Nobuyoshi Esaki, Kenji Inagaki

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10 Citations (Scopus)


Selenite (SeO32-) assimilation into a bacterial selenoprotein depends on thioredoxin (trx) reductase in Esherichia coli, but the molecular mechanism has not been elucidated. The mineral-oil overlay method made it possible to carry out anaerobic enzyme assay, which demonstrated an initial lag-phase followed by timedependent steady NADPH consumption with a positive cooperativity toward selenite and trx. SDS-PAGE/autoradiography using 75Se-labeled selenite as substrate revealed the formation of trx-bound selenium in the reaction mixture. The protein-bound selenium has metabolic significance in being stabilized in the divalent state, and it also produced the selenopersulfide (-S-SeH) form by the catalysis of E. coli trx reductase (TrxB).

Original languageEnglish
Pages (from-to)1184-1187
Number of pages4
JournalBioscience, Biotechnology and Biochemistry
Issue number6
Publication statusPublished - 2011



  • Anaerobic enzyme assay
  • Escherichia coli
  • Selenite
  • Selenopersulfide
  • Thioredoxin reductase

ASJC Scopus subject areas

  • Biotechnology
  • Biochemistry
  • Molecular Biology
  • Applied Microbiology and Biotechnology
  • Analytical Chemistry
  • Organic Chemistry

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