Active site
Waiting to bind
Free energy
Reaction coordinate
- Activation energy
- 22 kJ/mol
- Barrier drop
- −38 kJ/mol
- Net ΔG
- −24 kJ/mol
- Relative rate
- 10⁶×
From the ES well to ‡
How far the hill has fallen
Unchanged by the enzyme
From the Arrhenius factor
Bind
The substrate drifts into a complementary pocket. Induced fit closes the enzyme around it, forming the enzyme–substrate complex. The protein is a catalyst: it is regenerated at the end.
Lower the hill
The enzyme stabilizes the transition state, so the free-energy peak drops. A smaller Ea means a far larger fraction of collisions have enough energy to react. ΔG, the net drop from reactants to products, stays the same.
Release
The strained bond rearranges, products leave the pocket, and the free enzyme is ready for another turnover. Watch the marble roll a lower curve when the catalyst is bound.