title: The magnetic properties of the nickel cofactor F430 in the enzyme methyl-coenzyme M reductase of Methanobacterium thermoautotrophicum.
abstract: Cofactor 430 of methyl-coenzyme M reductase from Methanobacterium thermoautotrophicum was studied in both the extracted form in aqueous solution and protein-bound by using low-temperature magnetic-circular-dichroism spectroscopy. In both forms the nickel was present as high-spin paramagnetic nickel(II), spin S = 1, subject to almost equal zero-field splitting (cofactor F430, D = +9.0 cm-1, E/D = 0; methyl-coenzyme M reductase, D = +8.5 cm-1, [E/D[ = 0.2). This suggests identical axial co-ordination by oxygen ligand(s) both in aqueous cofactor F430 and in the investigated state of the protein.
authors.affiliation: School of Chemical Sciences, University of East Anglia, Norwich, U.K.
authors.forename: M R
authors.initials: MR
authors.lastname: Cheesman
authors.forename: D
authors.initials: D
authors.lastname: Ankel-Fuchs
authors.forename: R K
authors.initials: RK
authors.lastname: Thauer
authors.forename: A J
authors.initials: AJ
authors.lastname: Thompson
mesh_terms: D002942:Circular Dichroism; D003067:Coenzymes; D008280:Magnetics; D008665:Metalloporphyrins; D008667:Metalloproteins; D008772:Methylococcaceae / Q000201:enzymology*; D009532:Nickel; D010088:Oxidoreductases
chemical_list: D003067:Coenzymes; D008665:Metalloporphyrins; D008667:Metalloproteins; C023540:factor F430; D009532:Nickel; D010088:Oxidoreductases; C021572:methyl coenzyme M reductase