1. Catalysts

Overview of catalysis

Overview

  • 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

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