Analysis Note

Assayed according to the method of Yamanaka, Meth. Enzymol., 41(B), 138 (1975).

Application

Can be used for the production of D-mannitol.

This preparation is useful in the determination of mannitol in urine.

It has been used in a study to assess glucosylglycerol and glucosylglycerate as enzyme stabilizers.

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.

General description

The molecular weight of mannitol dehydrogenase is 136 kDa.

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.

Physical form

Lyophilized powder containing buffer salts, potassium phosphate, and dithiothreitol

Preparation Note

Partially purified

Unit Definition

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.