Characterization of the MCRred2 form of methyl-coenzyme M reductase: a pulse EPR and ENDOR study.
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.
Finazzo
Cinzia
C
Physical Chemistry, ETH Zurich, 8093 , Zurich, Switzerland.
Harmer
Jeffrey
J
Physical Chemistry, ETH Zurich, 8093 , Zurich, Switzerland.
Jaun
Bernhard
B
Organic Chemistry, ETH Zurich, 8093 , Zurich, Switzerland.
Duin
Evert C
EC
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.
Mahlert
Felix
F
Max-Planck-Institut für terrestrische Mikrobiologie and Laboratorium für Mikrobiologie, Fachbereich Biologie, Philipps-Universität, Karl-von-Frisch-Strasse, 35043 , Marburg, Germany.
Thauer
Rudolf K
RK
Max-Planck-Institut für terrestrische Mikrobiologie and Laboratorium für Mikrobiologie, Fachbereich Biologie, Philipps-Universität, Karl-von-Frisch-Strasse, 35043 , Marburg, Germany.
Van Doorslaer
Sabine
S
Physical Chemistry, ETH Zurich, 8093 , Zurich, Switzerland.|Spectroscopy in Biophysics and Catalysis (SIBAC Laboratory), University of Antwerp, Universiteitsplein 1, 2610 , Wilrijk, Belgium.
Schweiger
Arthur
A
Physical Chemistry, ETH Zurich, 8093 , Zurich, Switzerland. schweiger@phys.chem.ethz.ch.
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
D007527:Isoenzymes; D011758:Pyrroles; C049349:7-mercaptoheptanoylthreonine phosphate; D010769:Phosphothreonine; D010088:Oxidoreductases; C021572:methyl coenzyme M reductase; D009584:Nitrogen