title: Identification of axial ligands of cytochrome c552 from Nitrosomonas europaea.
abstract: Cytochrome c552 from Nitrosomonas europaea was analyzed by visible, EPR and MCD spectroscopies. The visible and MCD data show that histidine and methionine are the axial ligands to the heme iron of the ferric protein. The EPR spectrum of the cytochrome shows an atypical highly axial low spin (HALS) type signal with g-values that make it difficult to identify the axial ligands. These results reinforce the value of near-infrared MCD spectroscopy for assigning ligands in ferric heme systems and point out the difficulties in using only EPR spectroscopy for the same purpose. The description of another c-cytochrome exhibiting a HALS-type EPR signal will eventually be helpful in explaining the physical basis for this unusual signal.
authors.affiliation: Department of Genetics and Cell Biology, University of Minnesota, St. Paul 55108.
authors.forename: D M
authors.initials: DM
authors.lastname: Arciero
authors.forename: Q
authors.initials: Q
authors.lastname: Peng
authors.forename: J
authors.initials: J
authors.lastname: Peterson
authors.forename: A B
authors.initials: AB
authors.lastname: Hooper
mesh_terms: D002942:Circular Dichroism; D003574:Cytochrome c Group / Q000737:chemistry / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D005290:Ferric Compounds / Q000737:chemistry; D006418:Heme / Q000737:chemistry; D008024:Ligands; D009606:Nitrosomonas / Q000378:metabolism*; D010084:Oxidation-Reduction; D013053:Spectrophotometry
chemical_list: D003574:Cytochrome c Group; D005290:Ferric Compounds; D008024:Ligands; C083951:cytochrome c553; D006418:Heme; C022302:cytochrome C-552