Fructose-bisphosphate aldolase (EC: 4.1.2.13) [PMID:2199259, PMID:1412694] is a glycolytic enzyme that catalyses the reversible aldol cleavage or condensation of fructose-1,6-bisphosphate into dihydroxyacetone-phosphate and glyceraldehyde 3-phosphate. There are two classes of fructose-bisphosphate aldolases with different catalytic mechanisms: class I enzymes [PMID:3355497] are found in animals, do not require a metal ion, and are characterised by the formation of a Schiff base intermediate between a highly conserved active site lysine and a substrate carbonyl group, while the class II enzymes are produced in bacteria and fungi, and require an active-site divalent metal ion. This entry represents the class I enzymes.

In vertebrates, three forms of this enzyme are found: aldolase A is expressed in muscle, aldolase B in liver, kidney, stomach and intestine, and aldolase C in brain, heart and ovary. The different isozymes have different catalytic functions: aldolases A and C are mainly involved in glycolysis, while aldolase B is involved in both glycolysis and gluconeogenesis. Defects in aldolase B result in hereditary fructose intolerance.