This group contains proteins identified as alcohol dehydrogenases and glutathione-dependant formaldehyde dehydrogenases (FDH) of the zinc-dependent/medium chain alcohol dehydrogenase family. The MDR family uses NAD(H) as a cofactor in the interconversion of alcohols and aldehydes, or ketones. FDH converts formaldehyde and NAD to formate and NADH. 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. The medium chain alcohol dehydrogenase family (MDR) has 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.