Enzymatic Mechanism of Class I Aldolase

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Questions and Answers

What is the function of aldolase?

  • Regulates blood sugar levels
  • Breaks down fatty acids
  • Catalyzed reaction 4 of glycolysis (correct)
  • Synthesizes amino acids

What is the first step of the enzymatic mechanism of aldolase?

Substrate fructose-1,6-bisphosphate binds to enzyme.

What happens in step 2 of the reaction mechanism?

Epsilon amino group of Lys attacks the carbonyl of the substrate, forming protonated Schiff base with loss of H2O.

What occurs during step 3 of aldolase action?

<p>Asp acts as a general base, leading to aldol cleavage between the 3rd and 4th carbon, forming enamine intermediate and releasing product 1, glyceraldehyde-3-phosphate.</p> Signup and view all the answers

What is formed in step 4 after the enamine intermediate is protonated?

<p>A new protonated Schiff base complex is formed.</p> Signup and view all the answers

What happens in step 5 of the aldolase mechanism?

<p>The protonated Schiff base is hydrolyzed, releasing product 2, dihydroxyacetone phosphate, and the enzyme is free to begin a new cycle of catalysis.</p> Signup and view all the answers

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Study Notes

Function of Aldolase

  • Catalyzes reaction 4 in glycolysis
  • Cleaves biphosphorylated hexose into two 2-phosphorylated trioses

Substrate Binding

  • Fructose-1,6-bisphosphate is the substrate that binds to the aldolase enzyme
  • This initiates the first step of the enzymatic mechanism

Formation of Schiff Base

  • The epsilon amino group of lysine attacks the carbonyl of the substrate
  • This leads to the formation of a protonated Schiff base and the loss of water

Aldol Cleavage

  • Aspartate acts as a general base, facilitating aldol cleavage
  • Cleavage occurs between the 3rd and 4th carbon of the substrate
  • Produces glyceraldehyde-3-phosphate and forms an enamine intermediate

Tautomerization Process

  • The enamine intermediate is protonated by aspartate
  • Undergoes tautomerization to create a new protonated Schiff base complex

Hydrolysis of Schiff Base

  • The protonated Schiff base is hydrolyzed
  • Results in the release of the second product, dihydroxyacetone phosphate
  • The enzyme is now free to begin a new catalytic cycle

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