Aldolase: Step 4 of Glycolysis Flashcards
What enzyme cleaves fructose-1, 6-bisphosphate into two trioses?
Aldolase
What two trioses are formed from the cleavage of F 1, 6 P?
1) Glyceraldehyde-3-phosphate (GAP)
2) Dihydroxyacetone phosphate (DHAP)
What type of reaction is catalyzed by aldolase?
An aldol cleavage
What characterizes the products in the steps of glycolysis following the aldol cleavage by aldolase?
The products are three-carbon (rather than 6-carbon) molecules.
True or false: The aldol cleavage that generates dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (GAP) from FBP is readily reversible.
True
What does DHAP stand for?
dihydroxyacetone phosphate
What does GAP stand for?
glyceraldehyde 3-phosphate
Which of the two products in the reaction catalyzed by aldolase is on the direct path of glycolysis?
Glyceraldehyde 3-phosphate (GAP)
Which of the two products in the reaction catalyzed by aldolase is not on the direct path of glycolysis?
Dihydroxyacteone phosphate (DHAP)
What enzyme catalyzes the isomerization of dihydroxyacetone phosphate (DHAP) to glyceraldehyde phosphate (GAP) (and vice versa?
Triose phosphate isomerase (TPI or TIM)
What general kind of isomerization is catalyzed by TIM (triose phosphate isomerase)?
Interconversion of a ketose to/from an aldose
What contols the rate of reaction between the enzyme and substrate for triose phosphate isomerase (TIM)?
Diffusion
What is the effect of the efficient interconversion of GAP and DHAP allowed by TIM?
Equilibrium concentration is maintained
At equilibrium, what are the relative concentrations of dihydroxyacetone phosphate (DHAP) and (GAP)?
The concentration of DHAP is much greater (96%).
Why does the reaction between DHAP and GAP move readily in the direction of GAP?
Because subsequent steps of glycolysis are removing GAP
