Structural Biochemistry/Enzyme Catalytic Mechanism/Summary
Enzyme Catalysis: Summary
Enzymes accelerate reactions using :
Proximity and orientation effects
Preferential Transition State Binding
General acid/base catalysis
Metal ion catalysis
Enzymes accelerate chemical reactions by lowering the activation energy, DG‡.
Strong binding of the transition state and weak binding of the substrate leads to the maximum rate because all the binding energy is used to lower DG‡.
Any process that uses some of the binding energy for another purpose, e.g., a protein conformational change, will lower the maximum rate.
Under physiological conditions, the maximum rate is achieved by maximizing kcat/Km AND having Km greater than the physiological [S]. This means that most of the enzyme will be free to interact with a substrate molecule and that every encounter will lead to a reaction.