Polyol dehydrogenases: intermediate role in the bioconversion of rare sugars and alcohols.

Polyol dehydrogenases (PDHs) play a pivotal role in the biotransformation between rare sugar and alcohol. Among these PDHs, mannitol 2-dehydrogenase (MDH, EC 1.1.1.67), galactitol 2-dehydrogenase (GDH, EC 1.1.1.16), ribitol 2-dehydrogenase (RDH, EC 1.1.1.56), xylitol 4-dehydrogenase (XDH, EC 1.1.1.14), and arabitol 2-dehydrogenase (ArDH, EC 1.1.1.12) are the most studied. MDH can catalyze the transformation between D-fructose and mannitol as well as the transformation between D-arabitol and D-xylulose. In addition to MDH, the other PDHs including RDH, GDH, ArDH, and XDH are also important tools for the production of rare sugars including D-tagatose, allitol, D-xylulose, and L-xylulose. Concerning the intermediate function of PDH in the linkage of rare sugar and sugar alcohols, this review attempts to conclude their catalytic properties and potential applications.