xanthine dehydrogenase (XDH, XDHA)

Function

• key enzyme in purine degradation
• catalyzes oxidation of hypoxanthine to xanthine
• catalyzes oxidation of xanthine to uric acid
• has low oxidase activity towards aldehydes (in vitro)
• can be converted from dehydrogenase form to the oxidase form (xanthine oxidase) irreversibly by proteolysis or reversibly through oxidation of sulfhydryl groups
• interacts with BTN1A1 (putative)

Xanthine + NAD+ + H2O <--> urate + NADH

Xanthine + H2O + O2 <--> urate + H2O2

Cofactor:

• binds 2 2Fe-2S clusters
• FAD
• molybdopterin

Structure

• homodimer
• belongs to the xanthine dehydrogenase family
• contains 1 2Fe-2S ferredoxin-type domain
• contains 1 FAD-binding PCMH-type domain

Compartment

cytoplasm (putative), peroxisome, secreted

Expression

detected in milk (at protein level)

Pathology

• defects in XDH are the cause of xanthinuria type 1
• may contribute to the generation of reactive oxygen species
• may contribute to adult respiratory stress syndrome (ARDS) & may potentiate influenza infection through an oxygen metabolite-dependent mechanism

More general terms

• ketone oxidoreductase
• flavoprotein
• dehydrogenase
• oligomerizing protein
• metalloprotein
• phosphoprotein
• human longevity protein

More specific terms

• xanthine oxidase

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=7498
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:7498
• OMIM: https://mirror.omim.org/entry/278300
• OMIM: https://mirror.omim.org/entry/607633
• UniProt: http://www.uniprot.org/uniprot/P47989.html