This group represents a 10-formyltetrahydrofolate dehydrogenase (FDH). This enzyme catalyses the reaction: 10-formyltetrahydrofolate + H2O + NADP+ = tetrahydrofolate + CO2 + NADPH + H+
As such it acts as an NADP-dependent aldehyde dehydrogenase [PMID: 1848231]. It is composed of two catalytic domains (the N- and C-terminal domains), which are connected by a 100-amino acid residue linker (intermediate domain). The intermediate domain functions similarly to an acyl carrier protein by binding to 4'-phosphopantetheine [PMID: 17884809]. FDH differs from other members of the aldehyde dehydrogenase family in that it binds the 2'-phosphate group of NADP via a water-mediated contact with Gln600, which may contribute to the specificity of the enzyme for NADP over NAD [PMID: 17302434].