Biochem 3300 - Glycolysis II PI

  1. Reaction six substrate and products
    • (Glyceraldehyde-3-phosphate)x2
    • (1,3-Bisphosphoglycerate)x2
  2. ΔG'° of reaction six
    6.3 KJ mol-1
  3. Why is glyceraldehyde-3-phosphate important?
    It is the first high energy intermediate
  4. Key residues of glyceraldehyde-3-phosphate deyhydrogenase
    • Cysteine
    • Histidine
  5. Reaction six mechanism
    • 1. Cysteine's -S-H donates electrons to C3 resulting in tautomerization of C3=O to C3-O:-
    • 2. C3 donates it's proton to NAD+ reforming the C3=O bond
    • 3. NADH is exchanged for NAD+
    • 4. Pi-O:- attacks S-C3=O, histidine donates it's proton to cysteine's -S:-
    • 5. 1,3-Bisphosphoglycerate is eliminated
  6. How are phosphoglycerate kinase and hexokinase similar?
    • Both kinases
    • Both swing shut upon allosteric binding
    •    - Exclude water
  7. What does phosphoglycerate kinase do?
    • Removes Pi from 1,3-bisphosphate carbon 1, and phosphorylates ADP
    • Produces 3-phosphoglycerate as a biproduct
  8. ΔG'° of reaction seven
    -18.5 KJ mol-1
  9. Mechanism of reaction seven
    • a. Mg2+ coordinates ADP's α and β phoshates
    • b. β-phosphate attacks phosphate on 1,3-BPG's C1, causing the O-P oxygen to draw electrons from the bond
    • c. ATP is formed
  10. Substrate and products of reaction eight
    • 3-phosphoglycerate
    • 2-Phosphoglycerate
  11. Thing to know about reaction eight
    • Reversible
    • Mg2+ required
    • Specific amounts of 2,3-BPG are required for enzyme function
  12. ΔG'° of reaction eight
    4.4 KJ mol-1
  13. Key residue for phosphoglycerate mutase
  14. Mechanism of reaction eight
    • 1. Phosphorylated histidine phosphorylates C2-OH
    • 2. C3-P rephosphorylates His
  15. Reaction eight's tangential reaction (include enzyme and product)
    • 1,3-BPG -> 2,3-Bisphosphoglycerate
    • Via bisphosphoglycerate mutase
  16. Enzyme converting 2,3-Bisphosphoglycerate to 3-phosphoglycerate
    2,3-Bisphosphoglycerate phosphatase
  17. Why is 2,3-Bisphosphoglycerate important?
    Binds to deoxyhemoglobin and influences O2 affinity
  18. Where does synthesis and degradation of 2,3-Bisphosphoglycerate occur
  19. Reaction nine substrate and products
    • 2-phosphoglycerate
    • Phosphoenolpyruvate
  20. ΔG'° of reaction nine
    7.5 KJ mol-1
  21. Mechanism of reaction nine
    • i. Two Mg2+ ions coordinate the C1 carboxyl group
    • 1. Lysine abstracts proton C2-H, forming a terminal enol intermediate R-C2=COO2-(Mg2+)x2
    • 2. Glutamate deprotonates causing water to leave from the C3, allowing formation of phosphoenolpyruvate
  22. Why is fluorine an inhibitor of enolase?
    It can bind to the Mg2+ ions
  23. Products and substrates of reaction ten
    • Phosphoenol pyruvate, ADP
    • Pyruvate, ATP
  24. ΔG'° of reaction ten
    -31.4 KJ mol-1
  25. Key requirements for reaction ten
    Two Mg2+ ions (one for ADP, one for PEP)
  26. Basic steps of reaction ten
    • 1. Depshophorylation of PEP (ADP->ATP)
    • 2. Tautomerization of Enolpyruvate
Card Set
Biochem 3300 - Glycolysis II PI
Biochem 3300