In enzymology, a GDP-mannose 6-dehydrogenase () is an enzyme that catalyzes the chemical reaction
The 3 substrates of this enzyme are GDP-D-mannose, NAD<sup>+</sup>, and H<sub>2</sub>O, whereas its 3 products are GDP-D-mannuronate, NADH, and H<sup>+</sup>.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD<sup>+</sup> or NADP<sup>+</sup> as acceptor. The systematic name of this enzyme class is GDP-D-mannose:NAD<sup>+</sup> 6-oxidoreductase. Other names in common use include guanosine diphosphomannose dehydrogenase, GDP-mannose dehydrogenase, guanosine diphosphomannose dehydrogenase, and guanosine diphospho-D-mannose dehydrogenase. This enzyme participates in fructose and mannose metabolism.
This protein may use the morpheein model of allosteric regulation.
As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes , , and .