TALDO is a reversible enzyme of the non-oxidative branch of the Pentose Phosphate Pathway (PPP). The PPP plays a central role in generating ribose-5-phosphate for nucleic acid synthesis and NADPH for lipid biosynthesis. This NADPH is used in the body’s biosynthetic reactions as well as in the maintenance of glutathione in a reduced state for protection against oxidative stress. This pathway has both a reversible non-oxidative branch as well as an irreversible oxidative branch; both of which are inter-related. The TALDO enzyme catalyzes the transfer of a three-carbon keto unit, corresponding to dihydroxyacetone (DHA), from sedoheptulose-7-phosphate (S7P) to glyceraldehyde-3-phosphate (G3P) generating erythrose-4-phosphate (E4P) and fructose-6-phosphate (F6P).
Deficiency of this enzyme leads to a condition characterized by hepatosplenomegaly, liver failure, and cutis laxa. Individuals affected by this condition are also particularly susceptible to hepatocellular carcinoma, due to the resultant oxidative stress.