title: Proton NMR assignments and magnetic axes orientations for wild-type yeast iso-1-ferricytochrome c free in solution and bound to cytochrome c peroxidase.
abstract: Extensive proton hyperfine-shifted resonance assignments have been made for wild-type yeast iso-1-ferricytochrome c when it is free in solution and when it is noncovalently complexed to resting state cytochrome c peroxidase. Complete heme proton resonance assignments were made for free iso-1-ferricytochrome c, while for CcP-complexed iso-1-ferricytochrome c, 70% of heme proton assignments were made. Additional proton resonance assignments were made for hyperfine-shifted protons of amino acids near the heme. These assignments allowed identification of the most extensive set of complex-induced proton shifts yet reported for CcP/cytochrome c complexes. Several purely dipolar-shifted resonances from heme vicinity amino acid protons were also assigned in both free and complexed iso-1-ferricyt c. Both sets of resonance assignments allowed assessment of the origin of proton complex-induced shifts. Using the assigned dipolar-shifted proton resonances as a basis, the orientations of the principal axis systems of the paramagnetic susceptibility tensors for free and cytochrome c peroxidase-bound iso-1-ferricytochrome c were elucidated. The results indicated that the iso-1-ferricytochrome c magnetic axis system orientation shifts significantly upon complex formation. The direction of the complex-induced shifts for heme proton resonances is largely accounted for by the magnetic anisotropy changes. However, analysis of heme complex-induced shifts also reveals local changes in magnetic environment for two heme substituents, presumably through a specific structure change.
authors.affiliation: Department of Chemistry, Washington State University, Pullman 99164-4630, USA.
authors.forename: S F
authors.initials: SF
authors.lastname: Sukits
authors.forename: J E
authors.initials: JE
authors.lastname: Erman
authors.forename: J D
authors.initials: JD
authors.lastname: Satterlee
mesh_terms: D001665:Binding Sites; D003574:Cytochrome c Group / Q000737:chemistry* / Q000378:metabolism; D003578:Cytochrome-c Peroxidase / Q000378:metabolism*; D045304:Cytochromes c; D006418:Heme; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D012996:Solutions
chemical_list: C014059:CYC1 protein, S cerevisiae; D003574:Cytochrome c Group; D029701:Saccharomyces cerevisiae Proteins; D012996:Solutions; D006418:Heme; D045304:Cytochromes c; D003578:Cytochrome-c Peroxidase