Fructose Bisphosphate Aldolase

Fructose bisphosphate aldolaseFructose bisphosphate aldolase

Introduction and Structure

is an enzyme in glycolysis. It catalyzes the cleavage of fructose-1,6-bisphosphate into dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (GAP). It can also catalyze the cleavage of fructose 1-phosphate to diydroxyacetone and glyceraldehyde (GA). Different isozymes exhibit preferences for either or both of the substrates, depending on the role of the aldolase (i.e. gluconeogenesis versus glycolysis).Voet, D, Voet, J, & Pratt, C. (2008). Fundamentals of biochemistry, third edition. Hoboken, NJ: Wiley & Sons, Inc.</ref>

The reaction is an aldol cleavage, or otherwise termed, retro aldo condensation. Catalysis occurs first when the nucleophilic ε-amine group of Lys229 attacks the carbonyl (alpha) carbon of the substrate (FBP) in its open-ring state, pushing an electron pair to the oxygen of the carbonyl. The oxygen is protonated and leaves as water as a protonated is produced (an imine resulting from a ketone and amine) with the open-ring form of FBP, accompanied by electrostatic stabilization from . Aldol cleavage between C3 and C4 produces GAP and an enamine precursor to DHAP. Tautomerization, protonation and the hydrolysis of the Schiff base produce the final product of DHAP and regenerate the enzyme. The catalysis is driven by the more favorable stability of the protonated Schiff base compared to the enolate that would appear in basic catalysis pathways. can be seen in their specific regions concentrically located around the active site. Template:STRUCTURE 2ald

Kinetics

Regulation

References