Mannitol dehydrogenase (MDH) is a NAD-dependent enzyme, obtained from several organisms like, Lactobacillus brevis, Leuconostoc mesenteroides, Absidia glauca and Rhodococcus. MDH obtained from L. mesenteroides exhibits similarity in sequence with the medium-chain dehydrogenase/reductase protein family. It also contains four identical subunits of about 38 kDa in size.
