Reaction: galactitol + NAD+ = L-tagatose + NADH + H+
For diagram of reaction click here.
Other name(s): GatDH
Systematic name: galactitol:NAD+ 2-oxidoreductase (L-tagatose-forming)
Comments: The enzyme, characterized in the bacterium Rhodobacter sphaeroides, has a wide subtrate specificity. In addition to galactitol, it primarily oxidizes D-threitol and xylitol, and in addition to L-tagatose, it primarily reduces L-erythrulose, D-ribulose and L-glyceraldehyde. It is specific for NAD+. The enzyme also shows activity with D-tagatose (cf. EC 220.127.116.11, galactitol 2-dehydrogenase).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
1. Schneider, K.H., Jakel, G., Hoffmann, R. and Giffhorn, F. Enzyme evolution in Rhodobacter sphaeroides: selection of a mutant expressing a new galactitol dehydrogenase and biochemical characterization of the enzyme. Microbiology 141 (1995) 1865-1873. [PMID: 7551050]
2. Carius, Y., Christian, H., Faust, A., Zander, U., Klink, B.U., Kornberger, P., Kohring, G.W., Giffhorn, F. and Scheidig, A.J. Structural insight into substrate differentiation of the sugar-metabolizing enzyme galactitol dehydrogenase from Rhodobacter sphaeroides D. J. Biol. Chem. 285 (2010) 20006-20014. [PMID: 20410293]