So the energy of the transition state minus the energy of the reactants gives us this quantity known as the free energy of activation or simply the activation energy, the activation barrier of this particular chemical reaction. Now, what happens is when the enzyme actually takes in these molecules. So we have the enzyme in the enzyme. We have this special location in that enzyme that we're going to discuss in much more detail in the next lecture. But this special location in the enzyme is known as the active side. And it's the active side that creates a microenvironment and binds to these molecules here.