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acireductone dioxygenase (ARD), cupin domain Acireductone dioxygenase (ARD; also known as 1,2-dihydroxy-3-keto-5-methylthiopentene dioxygenase) catalyzes the oxidation of 1,2-dihydroxy-3-keto-5-methylthiopentene to yield two different products depending on which active site metal is present (Fe2+ or Ni2+) as part of the methionine salvage pathway. The ARD apo-enzyme, obtained after the metal is removed, is catalytically inactive. The Fe(II)-ARD reaction yields an alpha-keto acid and formic acid, while Ni(II)-ARD instead catalyzes a shunt out of the methionine salvage pathway, yielding methylthiocarboxylic acid, formic acid, and CO. ARD belongs to the cupin superfamily with a conserved "jelly roll-like" beta-barrel fold capable of homodimerization |
Jiyao W et al.(2023). "The conserved domain database in 2023.",