title: Characterization of the MCRred2 form of methyl-coenzyme M reductase: a pulse EPR and ENDOR study.
abstract: Methyl-coenzyme M reductase (MCR), which catalyses the reduction of methyl-coenzyme M (CH(3)-S-CoM) with coenzyme B (H-S-CoB) to CH(4) and CoM-S-S-CoB, contains the nickel porphinoid F430 as prosthetic group. The active enzyme exhibits the Ni(I)-derived axial EPR signal MCR(red1) both in the absence and presence of the substrates. When the enzyme is competitively inhibited by coenzyme M (HS-CoM) the MCR(red1) signal is partially converted into the rhombic EPR signal MCR(red2). To obtain deeper insight into the geometric and electronic structure of the red2 form, pulse EPR and ENDOR spectroscopy at X- and Q-band microwave frequencies was used. Hyperfine interactions of the four pyrrole nitrogens were determined from ENDOR and HYSCORE data, which revealed two sets of nitrogens with hyperfine couplings differing by about a factor of two. In addition, ENDOR data enabled observation of two nearly isotropic (1)H hyperfine interactions. Both the nitrogen and proton data indicate that the substrate analogue coenzyme M is axially coordinated to Ni(I) in the MCR(red2) state.
authors.affiliation: Physical Chemistry, ETH Zurich, 8093 , Zurich, Switzerland.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Finazzo
authors.affiliation: Physical Chemistry, ETH Zurich, 8093 , Zurich, Switzerland.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Harmer
authors.affiliation: Organic Chemistry, ETH Zurich, 8093 , Zurich, Switzerland.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Jaun
authors.affiliation: Max-Planck-Institut für terrestrische Mikrobiologie and Laboratorium für Mikrobiologie, Fachbereich Biologie, Philipps-Universität, Karl-von-Frisch-Strasse, 35043 , Marburg, Germany.|Department of Chemistry, Auburn University, Auburn, AL , 36849-5312, USA.
authors.forename: Evert C
authors.initials: EC
authors.lastname: Duin
authors.affiliation: Max-Planck-Institut für terrestrische Mikrobiologie and Laboratorium für Mikrobiologie, Fachbereich Biologie, Philipps-Universität, Karl-von-Frisch-Strasse, 35043 , Marburg, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Mahlert
authors.affiliation: Max-Planck-Institut für terrestrische Mikrobiologie and Laboratorium für Mikrobiologie, Fachbereich Biologie, Philipps-Universität, Karl-von-Frisch-Strasse, 35043 , Marburg, Germany.
authors.forename: Rudolf K
authors.initials: RK
authors.lastname: Thauer
authors.affiliation: Physical Chemistry, ETH Zurich, 8093 , Zurich, Switzerland.|Spectroscopy in Biophysics and Catalysis (SIBAC Laboratory), University of Antwerp, Universiteitsplein 1, 2610 , Wilrijk, Belgium.
authors.forename: Sabine
authors.initials: S
authors.lastname: Van Doorslaer
authors.affiliation: Physical Chemistry, ETH Zurich, 8093 , Zurich, Switzerland. schweiger@phys.chem.ethz.ch.
authors.forename: Arthur
authors.initials: A
authors.lastname: Schweiger
mesh_terms: D000465:Algorithms; D018360:Crystallography, X-Ray; D004578:Electron Spin Resonance Spectroscopy; D007527:Isoenzymes / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry; D010088:Oxidoreductases / Q000737:chemistry*; D010769:Phosphothreonine / Q000031:analogs & derivatives* / Q000737:chemistry; D011758:Pyrroles / Q000737:chemistry
chemical_list: D007527:Isoenzymes; D011758:Pyrroles; C049349:7-mercaptoheptanoylthreonine phosphate; D010769:Phosphothreonine; D010088:Oxidoreductases; C021572:methyl coenzyme M reductase; D009584:Nitrogen