Redox chemistry of cobalamin and iron-sulfur cofactors in the tetrachloroethene reductase of Dehalobacter restrictus

• Published in: FEBS letters Vol. 409; no. 3; pp. 421 - 425
• Main Authors: Schumacher, Wolfram, Holliger, Christof, Zehnder, Alexander J.B, Hagen, Wilfred R
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 16.06.1997
• Subjects: Bacteria, Anaerobic - chemistry; Bacteria, Anaerobic - enzymology; Biochemie; Biochemistry; Cobalamin; Cobalt - chemistry; Dehalobacter restrictus; Electron Spin Resonance Spectroscopy; Iron-sulfur; Iron-Sulfur Proteins - chemistry; Oxidation-Reduction; Oxidoreductases - chemistry; Oxidoreductases - isolation & purification; Reductive dechlorination; Substrate Specificity; Tetrachloroethene reductase; Titrimetry; Vitamin B 12 - chemistry; Tetrachloroethene reductase; Cobalamin; Dehalobacter restrictus; Reductive dechlorination; Iron-sulfur
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/S0014-5793(97)00520-6

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 E m(Co 1+/2+)=−350 mV and E m(Co 2+/3+)>150 mV and two electron-transferring [4Fe–4S] (2+;1+) clusters with rather low redox potentials of E m≈−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.