Reaction: (1) β-D-galacturonate + NAD+ = D-galactaro-1,5-lactone + NADH + H+
(2) β-D-glucuronate + NAD+ = D-glucaro-1,5-lactone + NADH + H+
Other name(s): uronate:NAD-oxidoreductase; uronic acid dehydrogenase
Systematic name: uronate:NAD+ 1-oxidoreductase
Comments: Requires Mg2+. The enzyme, characterized from the bacterium Agrobacterium fabrum, participates in oxidative degradation pathways for galacturonate and glucuronate. The enzyme can only accept the β anomeric form of the substrate [4]. The 1,5-lactone product is rather stable at cytosolic pH and does not hydrolyse spontaneously at a substantial rate.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 37250-98-9
References:
1. Kilgore, W.W. and Starr, M.P. Uronate oxidation by phytopathogenic pseudomonads. Nature (Lond.) 183 (1959) 1412-1413. [PMID: 13657147]
2. Boer, H., Maaheimo, H., Koivula, A., Penttila, M. and Richard, P. Identification in Agrobacterium tumefaciens of the D-galacturonic acid dehydrogenase gene. Appl. Microbiol. Biotechnol. 86 (2010) 901-909. [PMID: 19921179]
3. Andberg, M., Maaheimo, H., Boer, H., Penttila, M., Koivula, A. and Richard, P. Characterization of a novel Agrobacterium tumefaciens galactarolactone cycloisomerase enzyme for direct conversion of D-galactarolactone to 3-deoxy-2-keto-L-threo-hexarate. J. Biol. Chem. 287 (2012) 17662-17671. [PMID: 22493433]
4. Parkkinen, T., Boer, H., Janis, J., Andberg, M., Penttila, M., Koivula, A. and Rouvinen, J. Crystal structure of uronate dehydrogenase from Agrobacterium tumefaciens. J. Biol. Chem. 286 (2011) 27294-27300. [PMID: 21676870]