title: Redox chemistry of cobalamin and iron-sulfur cofactors in the tetrachloroethene reductase of Dehalobacter restrictus.
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.
authors.affiliation: Swiss Federal Institute for Environmental Science and Technology (EAWAG), Limnological Research Center, Kastanienbaum.
authors.forename: W
authors.initials: W
authors.lastname: Schumacher
authors.forename: C
authors.initials: C
authors.lastname: Holliger
authors.forename: A J
authors.initials: AJ
authors.lastname: Zehnder
authors.forename: W R
authors.initials: WR
authors.lastname: Hagen
mesh_terms: D001421:Bacteria, Anaerobic / Q000737:chemistry / Q000201:enzymology*; D003035:Cobalt / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D007506:Iron-Sulfur Proteins / Q000737:chemistry*; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry* / Q000302:isolation & purification; D013379:Substrate Specificity; D017186:Titrimetry; D014805:Vitamin B 12 / Q000737:chemistry*
chemical_list: D007506:Iron-Sulfur Proteins; D003035:Cobalt; D010088:Oxidoreductases; C098849:tetrachloroethene reductase; D014805:Vitamin B 12