These enzymes are heterodimers of a flavoprotein (fccBQ06530) and a diheme cytochrome (fccA; Q06529) that carry out hydrogen sulfide-dependent cytochrome Creduction. The diheme cytochrome folds into two domains, each of which resembles mitochondrial cytochrome c, with the two haem groups bound to the interior of the subunit. The flavoprotein subunit has a glutathione reductase-like fold consisting of a beta(3,4)-alpha(3) core, and an alpha+beta sandwich. The active site of the flavoprotein subunit contains a catalytically important disulfide bridge located above the pyrimidine portion of the flavin ring. The flavoprotein contains a C-terminal domain required for binding to flavin, and subsequent electron transfer.[4]Electrons are transferred from the flavin to one of the haem groups in the cytochrome. Both FAD and heme C are covalently bound to the protein.
^Kusai K, Yamanaka T (November 1973). "The oxidation mechanisms of thiosulphate and sulphide in Chlorobium thiosulphatophilum: roles of cytochrome c-551 and cytochrome c-553". Biochimica et Biophysica Acta (BBA) - Bioenergetics. 325 (2): 304–14. doi:10.1016/0005-2728(73)90106-0. PMID4357558.
^Fukumori Y, Yamanaka T (June 1979). "Flavocytochrome c of Chromatium vinosum. Some enzymatic properties and subunit structure". Journal of Biochemistry. 85 (6): 1405–14. doi:10.1093/oxfordjournals.jbchem.a132467. PMID222744.
^Sorokin DY, Gray GO, Gaul DF, Knaff DB (April 1983). "Partial purification and characterization of two soluble c-type cytochromes from Chromatium vinosum". Archives of Biochemistry and Biophysics. 222 (1): 78–86. doi:10.1016/0003-9861(83)90504-0. PMID6301383.
^ abcChen ZW, Koh M, Van Driessche G, Van Beeumen JJ, Bartsch RG, Meyer TE, Cusanovich MA, Mathews FS (October 1994). "The structure of flavocytochrome c sulfide dehydrogenase from a purple phototrophic bacterium". Science. 266 (5184): 430–2. Bibcode:1994Sci...266..430C. doi:10.1126/science.7939681. PMID7939681.
