Function
Catalyzes the oxidation of D-galacturonate and D-glucuronate to galactarate and D-glucarate, respectively. In fact, in water solution the substrate D-galacturonate is predominantly in pyranosic form whose beta anomer is converted by the enzyme to D-galactaro-1,5-lactone; in solution, this reaction product rearranges to the more stable D-galactaro-1,4-lactone. Makes part of the oxidative degradation pathway of D-galacturonate, which allows A.tumefaciens to utilize D-galacturonate as a sole carbon source. Cannot use NADP(+) instead of NAD(+) as cosubstrate. Is not active on D-galactose, D-glucose, D-galactonate and D-gluconate.