Component of the glyceraldehyde dehydrogenase which is involved the nonphosphorylated Entner-Doudoroff pathway. Catalyzes the oxidation of D-glyceraldehyde to yield glycerate. When the artificial electron acceptor 2,6-dichlorophenol-indophenol (Cl2Ind) is used, the enzyme shows a broad substrate range (glyceraldehyde-3-phosphate, formaldehyde, acetaldehyde, propionaldehyde and isobutyraldehyde), but is most active with D-glyceraldehyde. It is not known which acceptor is utilized in vivo. A + D-glyceraldehyde + H2O = (R)-glycerate + AH2 + H(+) Binds 1 FAD per subunit. Optimum pH is 6.7. At pH 6.7, glyceraldehyde is the predominant substrate, however at pH 7.5 the dehydrogenase exhibits activity preferentially towards the aliphatic aldehydes such as formaldehyde, acetaldehyde and propionaldehyde. Heterotrimer composed of a large chain (CutA), a medium chain (CutB) and a small chain (CutC).