Family members include the C termini of D-galactarate dehydratase (EC:188.8.131.52) which is thought to catalyze the reaction D-galactarate = 5-keto-4-deoxy-D-glucarate + H2O, and altronate hydrolase (altronic acid hydratase, EC:184.108.40.206), which catalyzes D-altronate = 2-keto-2-deoxygluconate + H2O. As purified, both enzymes are catalytically inactive in the absence of added Fe2+, Mn2+, and beta-mercaptoethanol. Synergistic activation of altronate hydrolase activity is seen in the presence of both iron and manganese ions, suggesting that the enzyme may have two ion binding sites. Mn2+ appears to be part of the enzyme active centre, but the function of the single bound Fe2+ ion is unknown. The hydratase has no Fe-S core.