Biochem FINAL Glycolysis reactions

Question 1

Reaction 1

Answer 1

Hexakinase (HK); Glucokinase in liver Kinase transfers phosphoryl group Nucleophilic attack by C6 - OH group on gammaP of ATP Mg2+ shields charges Highly exergonic reactions Conformational change; (Displaces H2O and prevent ATP hydrolysis from occuring.)

Question 2

What happens to [Glc]cyto during Reaction 1, and what does it cause.

Answer 2

Decrease; which makes passive transport into the cell more likely.

Question 3

Reaction 2

Answer 3

Phosphoglucose isomerase (PGI) Acid-Base mechanism

Question 4

Reaction 3

Answer 4

PFK (Similar to HK) Highly exergonic Point of regulation (PoR): Often exergonic

Question 5

Reaction 4

Answer 5

Fructose-1,6,-bisphosphate (FBP) <==Aldase===> GAP + DHAP

• Aldase:
  
  • Mechanism: Aldol Cleavage (Reverse of Aldol condensation)
    
    • FBP (6 Carbons) <===> GAP (3C) + DHAP (3C)

Question 6

Reaction 5

Answer 6

DHAP <===> GAP

• Triose phosphate isomerase (TIM)
  
  • Catalytically perfect enzyme
• Shows why reaction 2 is important
  
  • Without step 2 we would end up with 2C + 4C

Question 7

AAR of Investment Stage

Answer 7

2 ATP per Glc

2 GAP per Glc

Question 8

Reaction 6

Answer 8

• GAPDH
  
  • Produces NADH by oxidizing GAP
  • Adds Di to GAP
• NAD(+) + 2e(-) to H <==>NADH
• NADH
  
  • Goes to ETC (Electron Transport Chain) If O2 is present
  • If no O2, lactic Acid fermentation

Question 9

Reaction 7

Answer 9

• 1,3-BPG + ADP <==(PGK)/(Mg2+)===> 3PG
• PGK
  
  • Named after Reverse reaction
  • ATP regenerated regardless of [O2]
    
    • Substrate level phosphorylation

Question 10

Reaction 8

Answer 10

3 PG <===PGM===> 2PG

• PGM (Phosphoglycerate mutase)
  
  • Phosphoryl group transfer
    
    • Not intramolecular
    • Moves it from the 3C to 2C
• During process 2,3-bisphosphoglycerate is produced.
  
  • This reduces O2 affinity in Hb
    *

Question 11

Reaction 9

Answer 11

• Enolase
  
  • Dehydraation rxn
• Produces PEP
  
  • PEP is known as a “High-energy” intermediate

Question 12

Reaction 10

Answer 12

• Pyruvate Kinase (PK)
  
  • Named after reverse reaction
• Substrate level phosphorylation

Question 13

AAR of “Payoff” Stage

Answer 13

• For each Glc
  
  • Consumed:
    
    • 2 ATP
  • Produced:
    
    • 4 ATP
    • 2 NADH
  • Net:
    
    • 2 ATP