Activation Energy, Transition State & Reaction Intermediates Explained

[lha08]

Homework Statement

I'm a little confused as to the concept of activation energy, transition state, and reaction intermediates...For example, I know that the activation energy is the difference between the ground state of the reactants and the transition state but on a diagram, does the top hill represent the transition state or the reaction intermediates? The thing is that supposedly the transition state is not a chemical species, its just a fleeting moment, but is this particular state represented by the reaction intermediates or is this state just between the formation of the ES and EP complexes?

Homework Equations

The Attempt at a Solution

 

[Borek]

If there is a multistep reaction, intermediates are in the valleys between tops occupied by transition states.

 

[lha08]

If there is a multistep reaction, intermediates are in the valleys between tops occupied by transition states.

I'm just wondering, in terms of the activation energy, if the enzyme binds complementary to the transition state, is the activation energy first lowered by the binding energy that is released when some weak noncovalent interactions are formed between the enzyme-substrate complex, and then the binding energy that is released when the ES noncovalently binds further lowers the activation energy?

 

[Borek]

I can be wrong, but as far as I can tell enzyme doesn't bind to the transition state, transition state appears after enzyme binds to the molecule.