Characterization of a nine heme cytochrome by NMR

A multiheme cytochrome c was isolated from the periplasm of the sulphate reducing bacterium, Desulfovibrio desulfuricans ATCC 27774. This protein contains nine hemes with bishistidinyl axial coordination and is part of a transmembrane complex which is involved in electron transfer across the cytoplasmic membrane for the reduction of sulphate. Nuclear magnetic resonance spectra in partially and fully oxidised samples allowed the preliminary assignment of the heme proton resonances. The chemical shifts of the heme methyl groups of the nine-heme cytochrome c are also predicted on the basis of the crystal structure. (author)