Biochem 3300 - Glycolysis I PI

  1. Major pathways of glucose utilization
    • Storage - Glycogen, starch, sucrose
    • Pentose phosphate pathway (oxidation) - Ribose-5-phosphate
    • Glycolysis (oxidation) - Pyruvate
  2. Two broad phases of glycolysis
    • Preparatory phase
    • Payoff phase
  3. Enzymes of the preparatory phase (in order)
    • 1. Hexokinase
    • 2. Phosphohexose isomerase
    • 3. Phosphofructokinase-1
    • 4. Aldolase
    • 5. Triose phosphate isomerase
  4. Substrate and products of the preparatory phase
    • Glucose (6C)
    • Glyceraldehyde-3-phosphate (3C)
    • Dihydroxyacetone phosphate (3C)
  5. Steps of preparatory phase that use ATP or NAD+
    1 and 3, both ATP
  6. Enzymes of the payoff phase (in order)
    • 1(6)   - Glyceraldehyde-3-phosphate dehydrogenase
    • 2(7)   - Phosphoglycerate kinase
    • 3(8)   - Phosphoglycerate mutase
    • 4(9)   - Enolase
    • 5(10) - Pyruvate kinase
  7. Substrate and products of the payoff phase
    • (Glyceraldehyde-3-phosphate)x2
    • (Pyruvate)x2
  8. Stages of the payoff phase using ADP or NAD+
    • (1)6   - (NAD+)x2
    • (2)7   - ADP )x2
    • (5)10 - ADP )x2
  9. Which step in glycolysis is committing?
    Step one - Glucose phosphorylation
  10. Why is glucose converted to fructose?
    Symmetry - Production of two 3C compounds
  11. End products of glycolysis
    • (ATP)x2
    • (NADH)x2
    • (H+)x2
    • (Pyruvate)x2
  12. First reaction in glycolysis
    Phosphorylation of glucose (hexokinase)
  13. Key steps of reaction 1
    • 1. Mg2+ coordinates the β and γ phosphates altering their conformation
    • 2. 6' :OH attacks the γ phosphate
    • 3. The γ phosphate bond donates electrons to the β phosphate oxygen
    • 6. ADP and glucose-6-phosphate are formed
  14. ΔG'° of phosphorylation of glucose
    -16.7 KJ mol-1
  15. How does hexokinase function?
    • Allostery - ATP and glucose
    • Two lobes swing together on substrate binding
  16. Reaction 2, products and substrates
    • Glucose-6-phosphate (aldose)
    • Fructose-6-phosphate (ketose)
  17. C=O bond on linear glucose
    Carbon 1 (aldose)
  18. C=O bond on linear fructose
    Carbon 2 (ketose)
  19. What type of reaction does phosphohexose catalyze?
    Acid-base
  20. Key steps of reaction 2
    • 1. The O-C1 of glucose-6-phosphate abstracts a proton from an acidic residue, breaking the O-C1 bond
    • 2a. A basic residue abstracts a proton from C2
    • 2b. The sugar tautomerizes forming a terminal enol around C1
    • 3a. The C2=C1 bond abstracts the proton abstracted by the basic residue
    • 3b. The C2-OH forms a ketone, eliminating a proton
    • 4a. The acidic residue abstracts the proton from C5-OH
    • 4b. The C5-O: attacks C2=O, forming a five membered ring
    • 5. C2-O- is neutralized with aqueous H+
Author
Ant
ID
314979
Card Set
Biochem 3300 - Glycolysis I PI
Description
Biochem 3300
Updated