Catalyzes the interconversion of galactitol to the rare sugar L-tagatose (PubMed:7551050). Shows activity with a wide range of substrates, and catalyzes the oxidation of a variety of polyvalent aliphatic alcohols and polyols to the corresponding ketones and ketoses, respectively, and in the reverse reaction, it reduces ketones with high stereoselectivity yielding the corresponding S-configurated alcohols (PubMed:7551050, PubMed:15296184). Shows high activity with D-threitol, xylitol, 1,2-hexanediol, 1,2-pentanediol, 2-hexanol, L-erythrulose, D-ribulose and acetoin (PubMed:7551050). Specific for NAD(+) (PubMed:7551050). galactitol + NAD(+) = H(+) + keto-L-tagatose + NADH Can use Mg(2+), Mn(2+), Ni(2+) or Co(2+). Inhibited by the chelating agents EDTA and alpha,alpha'-dipyridyl (PubMed:7551050). Inhibited by Zn(2+) and Fe(2+) (PubMed:7551050). Optimum pH is 10.5 with 1,2-hexanediol as substrate. Optimum pH is 4.0 with acetoin as substrate. Homotetramer. Constitutively expressed. The wide substrate spectrum and the stereoselective mode of action make GDH a very interesting enzyme for the production of optically pure building blocks in the chemical synthesis of bioactive compounds (PubMed:15296184). GDH could be covalently immobilized via thiol bonds onto the surface of a gold electrode, which represents a proof-of-concept for the development of reactors for electrochemical synthon preparation using dehydrogenases (PubMed:19778027). Belongs to the short-chain dehydrogenases/reductases (SDR) family.