Members of this protein resemble conventional xanthine dehydrogenase enzymes, which depend on molybdenum cofactor - molybdopterin bound to molybdate with two sulfur atoms as ligands. But all members of this family occur in species that contain markers for the biosynthesis of enzymes with a selenium-containing form of molybdenum cofactor. The member of this family from Enterococcus faecalis has been shown to act as a xanthine dehydrogenenase, and its activity if dependent on SelD (selenophosphate synthase), selenium, and molybdenum [, ].
This gene has been characterised in Bacillus subtilis []as the molybdopterin binding-subunit of xanthine dehydrogenase (pucD), acting in conjunction with pucC, the FAD-binding subunit and pucE, the FeS-binding subunit. The more common XDH complex () includes the xdhB gene which is related to pucD. It appears that most of the relatives of pucD outside of this narrow clade are involved in other processes as they are found in unrelated genomic contexts, contain the more common XDH complex and/or do not appear to process purines to allantoin.
Members of this protein family are PucB proteins found in Bacillus subtilis []. The expression of this protein is located in an operon with the structural subunits of xanthine dehydrogenase, and has been found to be essential for XDH activity. Some members of this family appear to have a distant relationship to the MobA protein involved in molybdopterin biosynthesis, although this may be coincidental.
This protein has been characterised in Bacillus subtilis []as the iron-sulphur cluster binding-subunit of xanthine dehydrogenase (pucE), acting in conjunction with pucC, the FAD-binding subunit and pucD, the molybdopterin binding subunit. The more common XDH complex () includes the xdhA gene as the Fe-S cluster binding component.
This entry includes aldehyde oxidases (AOXs) and xanthine dehydrogenases (XDHs). They are both molybdenum cofactor (Moco) containing enzymes []. AOX catalyses the reaction:aldehyde + H(2)O + O(2) = a carboxylic acid + H2O2 It binds 2 2Fe-2S clusters uses FAD and molybdopterin as cofactors. XDH has the same cofactors and some of them can be converted from the dehydrogenase form (D) to the oxidase form (O). This can be done irreversibly by proteolysis or reversibly through the oxidation of sulfhydryl groups []. This enzyme catalyses three reactions:Xanthine + H2O + NAD+= urate + NADHHypoxanthine + H2O + NAD+= xanthine + NADHXanthine + H2O + O2 = urate + H2O2In Arabidopsis thaliana, the molybdenum cofactor sulfurase ABA3 is needed for post-translational activation of aldehyde oxidase and xanthine dehydrogenase. It does this by transferring a sulfur atom to the desulfo-molybdenum cofactor of these enzymes [, ].
