| Description | Xanthine dehydrogenase is a complex metallo-flavoprotein catalysing the oxidation of hypoxanthine to xanthine followed by oxidation of xanthine to uric acid, linked to the reduction of NAD(+). Additionally, this enzyme can catalyse the oxidative hydroxylation of purines, pyrimidines, pterins, and aldehyde substrates. The mammalian form of this enzyme is a homodimer in which each monomer acts as an independent catalytic unit, while the bacterial form is a cytoplasmic heterotetramer composed of two small (alpha) and two large (beta) subunits [ ].In the bacterial enzyme, each heterotetramer is composed of two functionally independent large-small heterodimers [ ]. The small subunit binds two iron-sulphur clusters and FAD, while the large subunit binds molybdenum cofactor (MoCF). The small unit is composed of an N-terminal iron-sulphur binding domain with a ferredoxin-like fold, and a C-terminal FAD-binding domain similar in structure to other flavoproteins. The large subunit contains the Moco cofactor, located near the subunit interface, the substrate-binding site, and the site of dimerisation between heterodimers. The overall fold of the protein is similar to that of the mammalian enzyme, despite the difference in subunit composition. During catalysis, the electrons derived from substrate oxidation are transferred to molybdenum, then passed via the iron-sulphur clusters to the FAD cofactor, which is the site of NAD(+) reduction.This entry represents the small subunit of the bacterial enzyme. | Name | Xanthine dehydrogenase, small subunit, bacteria |
| Short Name | Xanth_DH_ssu_bac | Type | Family |
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