Glycolysis (detail) Flashcards
Step 1: phosphorylation of glucose
Irreversible
Enzyme: Hexokinase
- Transferase
- Glucokinase in liver
Requires ATP and Mg2+ to generate ADP
Product: Glucose-6-phosphate
Exergonic
Step 2: isomerization of Glucose-6-phosphate to Fructose-6-phosphate
Reversible
Enzyme: phosphohexose isomerase
- Isomerase
Requires Mg2+
Step3: Phosphorylation of Fructose 6-Phosphate to Fructose 1,6- Bisphosphate
Irreversible
Phosphofructokinase-1 (PFK-1)
- Transferase
- Activated by PFK-2 (converts F6P to F26BP).
- F26BP activates PFK-1
- stimulated by insulin and inhibited by glucagon.
Requires ATP and Mg2+ to generate ADP
Step 3 is rate limiting
Exergonic
Step 4: Cleavage of Fructose 1,6 Bisphosphate
Reversible
Enzyme: aldolase
- lyase
Yields:
- glyceraldehyde 3- phosphate (G3P)
a. Aldose - dihydroxyacetone phosphate (DHAP)
a. Ketose
Endergonic
Stage 5: Interconversion of the triose phosphate
Reversible
Enzyme: Triosephosphate Isomerase
- Isomerase
glyceraldehyde 3- phosphate (G3P) continues in the glycolysis pathway
Endergonic
Step 6: Oxidation of Glyceraldehyde 3-phosphate to 1,3- Bisphosphoglycerate
Reversible
Enzyme: Glyceraldehyde 3-phosphate dehydrogenase
- Oxidoreductase
Requires NAD+ and yields NADH
Endergonic
Step 7: Transfer or phosphate from 1,3- Bisphosphoglyerate to ADP
Reversible
Enzyme: Phophoglycerate kinase
- Transferase
Requires ADP and Mg2+ To generate ATP and have recovered ATP reaching break even.
Exergonic
Step 8: Isomerization of 3- phosphoglycerate to 2-phosphoglycerate
Reversible
Enzyme: Phosphoglycerate mutase
- Isomerase
Endergonic
Step 9: Dehydration of 2-phosphoglycerate to phosphoenolpyruvate
Reversible
Enzyme: Enolase
- Lyase
Requires Mg2+
Endergonic
Step 10: Transfer if the phosphorylation group from phosphoenolpyruvate to ADP
Irreversible
Enzyme: Pyruvate kinase
- Transferase
Requires ADP, Mg2+ and K+ to generate ATP and enolpyruvate.
Enolpyruvate tautomerizes into PYRUVATE
Exergonic
