Succinate Dehydrogenase Loss in Familial Paraganglioma: Biochemistry, Genetics, and Epigenetics

Figure 3

Structure of succinate dehydrogenase [20]. The enzyme is conserved through evolution and has two transmembrane subunits (SDHC and SDHD) and two matrix subunits (SDHA and SDHB). SDHA contains a bound FAD cofactor and the binding site for succinate. SDHB has three Fe-S centers. Heme b and ubiquinone are sandwiched between SDHC and SDHD. Electron pairs move from the substrate succinate to FAD, through the three Fe-S centers, and then to ubiquinone. Heme b prevents reactive oxygen species formation and does not participate in electron transfer. IMS (intermembrane space); IMM (inner mitochondrial membrane).