Overview of catalysis
- A reaction at equilibrium has no net change in the concentration of the reactants.
- The reaction will be spontaneous if the ΔGp < ΔGr.
- A catalyst lowers the free energy of the transition state. It does not change the free energy of the reaction itself.
- Biological catalysts increase the rate of reaction by 5-7 orders of magnitude.
- Not all catalysts are proteins: some are made of RNA. The synthesis of proteins, for example, relies on a ribosomal RNA catalyst.
Example: Glucose + APT => Glucose-6-phospate + ADP.
Here ΔG<0, but the reaction is made 10,000,000 faster by hexokinase
Activation Energy: the larger it is, the slower the reaction. It’s the hump a reaction needs to overcome to go forward. These are often insurmountable without a catalyst.
E + S <- -> ES <- -> EP <- -> P + E
ES = enzyme-substrate complex
ES = enzyme-product complex