Full assignment of heme redox potentials of cytochrome <i>c</i>₃ of <i>D. vulgaris</i> Miyazaki F by ¹H‐NMR

Abstract

Site-specific heme assignment of the 1H-NMR spectrum of cytochrome c3 of D. vulgaris Miyazaki F, a tetraheme protein, was established. The major reduction of the heme turned out to take place in the order of hemes I, III, IV and II (numbering in the crystal structure). The hemes with the smallest and greatest solvent accessibility were reduced at the highest and lowest potentials on average, respectively. A cooperative interheme interaction was attributed to a pair of the closest hemes, namely, hemes III and IV. This assignment can provide the physiochemical basis for the elucidation of electron transfer of this protein.