In enzymology, a mannitol-1-phosphate 5-dehydrogenase (EC 1.1.1.17) is an enzyme that catalyzes the chemical reaction

D-mannitol 1-phosphate + NAD⁺ ${\displaystyle \rightleftharpoons }$ D-fructose 6-phosphate + NADH + H⁺

Thus, the two substrates of this enzyme are D-mannitol 1-phosphate and NAD⁺, whereas its 3 products are fructose 6-phosphate, NADH and H⁺.

This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD⁺ or NADP⁺ as acceptor. The systematic name of this enzyme class is D-mannitol-1-phosphate:NAD⁺ 2-oxidoreductase. Other names in common use include hexose reductase, mannitol 1-phosphate dehydrogenase, D-mannitol-1-phosphate dehydrogenase, and fructose 6-phosphate reductase. This enzyme participates in fructose and mannose metabolism.

• D-Mannitol

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• Wolfe JB; Kaplan NO (1956). "D-Mannitol 1-phosphate dehydrogenase from Escherichia coli". J. Biol. Chem. 218 (2): 849–869. doi:10.1016/S0021-9258(18)65848-X. PMID 13295236.