In enzymology, S-(hydroxymethyl)glutathione dehydrogenase () is an enzyme that catalyzes the chemical reaction
The two substrates of this enzyme are S-(hydroxymethyl)glutathione and oxidised nicotinamide adenine dinucleotide (NAD<sup>+</sup>). Its products are S-formylglutathione, reduced NADH, and a proton. The enzyme can also use the alternative cofactor, nicotinamide adenine dinucleotide phosphate.
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 S-(hydroxymethyl)glutathione:NAD<sup>+</sup> oxidoreductase. Other names in common use include NAD-linked formaldehyde dehydrogenase (incorrect), formaldehyde dehydrogenase (incorrect), formic dehydrogenase (incorrect), class III alcohol dehydrogenase, ADH3, &chi, -ADH, FDH (incorrect), formaldehyde dehydrogenase (glutathione) (incorrect), GS-FDH (incorrect), glutathione-dependent formaldehyde dehydrogenase (incorrect), NAD-dependent formaldehyde dehydrogenase, GD-FALDH, and NAD- and glutathione-dependent formaldehyde dehydrogenase. This enzyme participates in methane metabolism.
As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes and .