Fructose-1,6-bisphosphate aldolase or, as it is more commonly known, aldolase, is a tetrameric protein catalyzing the cleavage of fructose-1,6-bisphosphate (F1,6BP) to dihydroxyacetone phosphate (DHAP) and D-glyceraldehyde-3-phosphate (G3P).

F1,6BP <=> Dihydroxyacetone Phosphate + D-Glyceraldehyde-3-Phosphate ( = +23.9 kJ/mol)

The reaction is common to both glycolysis and gluconeogenesis.

The of the reaction indicates a strongly endergonic reaction under standard state conditions, but intracellular substrate concentrations (determined in rabbit skeletal muscle) reveal an overall G of -1.3 kJ/mol, consistent with flux in the direction of cleavage normally. Under conditions in which gluconeogenesis is favored, the reaction can be readily reversed to favor F1,6BP formation. Thus, aldolase functions in both glycolysis and gluconeogenesis.

A different kind of aldolase activity in the liver, called Aldolase B, acts on fructose-1-phosphate to yield dihydroxyacetone phosphate and D-glyceraldehyde.

Previous step of glycolysis; Next step of glycolysis

INTERNET LINKS:

1. RasMol Image (slow)

2. Glycolysis/Gluconeogenesis