ATP can be made in 3 ways :
- substrate level phosphorylation (animals- glycolysis)
- oxidative phosphorylation (animals- mitochondria and electron transport chain)
- photophosphorylation (plants)
First Phase Enzymes
- Phosphohexose isomerase
- Phospho-fructokinase-1 (PFK-1)
- Triose phosphate isomerase
Hexokinase and PFK-1 are both enzymes for the irreversible reactions of the first phase. Their reactions are energetically favorable due to a large negative change of free energy(ΔG)
Second Phase Enzymes
6. Glyceraldehye 3-phosphate dehydrogenase
7. Phosphoglycerate kinase
8. Phosphoglycerate mutase
10. Pyruvate kinase
The most energetically favorable reaction in glycolysis is reaction 10. between phosphoenolpyruvate to pyruvate using pyruvate kinase. The reaction is irreversible due to ΔG being very negative.
ΔG is close to zero when the reaction is reversible.