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Redox chemistry of cobalamin and iron‐sulfur cofactors in the tetrachloroethene reductase of Dehalobacter restrictus
Author(s) -
Schumacher Wolfram,
Holliger Christof,
Zehnder Alexander J.B,
Hagen Wilfred R
Publication year - 1997
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(97)00520-6
Subject(s) - chemistry , cofactor , cobalamin , carbon monoxide dehydrogenase , iron–sulfur cluster , redox , enzyme , reductase , metalloprotein , stereochemistry , biochemistry , inorganic chemistry , carbon monoxide , catalysis , vitamin b12
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.