S-class cytochromes c have a variety of folding patterns: structure of cytochrome c-553 from Desulfovibrio vulgaris determined by the multi-wavelength anomalous dispersion method.

The three-dimensional structure of cytochrome c-553 isolated from sulfate-reducing bacterium, Desulfovibrio vulgaris Miyazaki F strain, has been determined by the multi-wavelength anomalous dispersion technique with use of synchrotron radiation. The result shows that bacterial S-class cytochromes c have a variety of folding patterns. The relative location of two a-helices at amino- and carboxyl-terminals and the style of bonding to the heme group show "cytochrome c folding," but other regions of the structure are different from those of other cytochromes c previously reported. The results also give useful information about the location of sulfate-reducing bacterium on the phylogenetic tree of the bacterial cytochromes c superfamily.