Formaldehyde dehydrogenase (FDH) is a member of the zinc-dependent/medium chain alcohol dehydrogenase family. Formaldehyde dehydrogenase (aka ADH3) may be the ancestral form of alcohol dehydrogenase, which evolved to detoxify formaldehyde. This CD contains glutathione dependant FDH, glutathione independent FDH, and related alcohol dehydrogenases. FDH converts formaldehyde and NAD(P) to formate and NAD(P)H. The initial step in this process the spontaneous formation of a S-(hydroxymethyl)glutathione adduct from formaldehyde and glutathione, followed by FDH-mediated oxidation (and detoxification) of the adduct to S-formylglutathione. Unlike typical FDH, Pseudomonas putida aldehyde-dismutating FDH (PFDH) is glutathione-independent. The medium chain alcohol dehydrogenase family (MDR) have a NAD(P)(H)-binding domain in a Rossmann fold of a beta-alpha form. The N-terminal region typically has an all-beta catalytic domain. These proteins typically form dimers (typically higher plants, mammals) or tetramers (yeast, bacteria), and have 2 tightly bound zinc atoms per subunit.