Redox Chemistry of Cobalamin and Iron-Sulfur Cofactors in the Tetrachloroethene Reductase of Dehalobacter Restrictus

FEBS Lett. 1997 Jun 16;409(3):421-5. doi: 10.1016/s0014-5793(97)00520-6.

Abstract

Respiration of Dehalobacter restrictus is based on reductive dechlorination of tetrachloroethene. The terminal component of the respiratory chain is the membrane-bound tetrachloroethene reductase. The metal prosthetic groups of the purified enzyme have been studied by optical and EPR spectroscopy. The 60-kDa monomer contains one cobalamin with Em(Co[1+/2+]) = -350 mV and Em(Co[2+/3+]) > 150 mV and two electron-transferring [4Fe-4S](2+;1+) clusters with rather low redox potentials of Em approximately -480 mV. The cob(II)alamin is present in the base-off configuration. A completely reduced enzyme sample reacted very rapidly with tetrachloroethene yielding base-off cob(II)alamin rather than trichlorovinyl-cob(III)alamin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacteria, Anaerobic / chemistry
  • Bacteria, Anaerobic / enzymology*
  • Cobalt / chemistry
  • Electron Spin Resonance Spectroscopy
  • Iron-Sulfur Proteins / chemistry*
  • Oxidation-Reduction
  • Oxidoreductases / chemistry*
  • Oxidoreductases / isolation & purification
  • Substrate Specificity
  • Titrimetry
  • Vitamin B 12 / chemistry*

Substances

  • Iron-Sulfur Proteins
  • Cobalt
  • Oxidoreductases
  • tetrachloroethene reductase
  • Vitamin B 12