title: Comparison of the solution and crystal structures of mitochondrial cytochrome c. Analysis of paramagnetic shifts in the nuclear magnetic resonance spectrum of ferricytochrome c.
abstract: The two accompanying papers describe the assignment of methyl-containing spin-systems in the 1H nuclear magnetic resonance spectra of tuna ferricytochrome c and tuna ferrocytochrome c. At present, 104 resonances from 208 C-H protons are assigned in both oxidation states. In this paper, the difference in chemical shift of a resonance between the two oxidation states is used together with a dipolar model of the unpaired electron spin of ferricytochrome c to compare the structure of cytochrome c in solution with three high-resolution structures of cytochrome c obtained by X-ray diffraction in single crystals. The overall protein fold and the positions of most of the haem-packing residues are shown to be invariant between the crystal and solution. However, three regions of the protein, at the C terminus, around the haem propionic acid groups and at the haem crevice near thioether-2, are found to undergo conformational changes on the removal of crystal packing constraints.
authors.forename: G
authors.initials: G
authors.lastname: Williams
authors.forename: N J
authors.initials: NJ
authors.lastname: Clayden
authors.forename: G R
authors.initials: GR
authors.lastname: Moore
authors.forename: R J
authors.initials: RJ
authors.lastname: Williams
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003574:Cytochrome c Group; D006418:Heme; D009682:Magnetic Resonance Spectroscopy; D008928:Mitochondria / Q000032:analysis*; D010084:Oxidation-Reduction; D011487:Protein Conformation; D011522:Protons; D012996:Solutions; D014413:Tuna; D014961:X-Ray Diffraction
chemical_list: D003574:Cytochrome c Group; D011522:Protons; D012996:Solutions; D006418:Heme