Description
General description
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.
Mannitol dehydrogenase is a cytoplasmic enzyme whose primary role is the regulation of intracellular levels of the sugar alcohol mannitol in plants. It catalyzes the pyridine nucleotide dependent reduction of fructose to mannitol.
The molecular weight of mannitol dehydrogenase is 136 kDa.
Application
Can be used for the production of D-mannitol.
It has been used in a study to assess glucosylglycerol and glucosylglycerate as enzyme stabilizers.
This preparation is useful in the determination of mannitol in urine.
Biochem/physiol Actions
Mannitol dehydrogenase (MDH) helps to catalyze the pyridine nucleotide-dependent oxidation of D-mannitol to D-fructose. Mannitol dehydrogenase (MDH) obtained from L. mesenteroides is highly specific for the conversion fructose and mannitol.
Physical form
Lyophilized powder containing buffer salts, potassium phosphate, and dithiothreitol
Preparation Note
Partially purified
Analysis Note
Assayed according to the method of Yamanaka, Meth. Enzymol., 41(B), 138 (1975).
Other Notes
One unit will reduce 1.0 μmole of D-fructose per min in the presence of NADH at pH 5.3 at 30°C. One unit of enzyme, as defined above, is equivalent to approximately 1.8 units of enzyme, as described by Lunn et al., one unit will oxidize 1.0 μmole of D-mannitol per min in the presence of NAD at pH 8.6 at 40°C.
