And now we begin to add the substrate that the enzyme actually catalyzes. What will begin to take place? Well, initially, this is the reaction that we're going to see take place. So basically, on the reactant side, we have the enzyme by itself, we have the substrate by itself, and then a reaction takes place that has a raid constant of K one. And this reaction basically is the reaction in which the substrate actually goes on and binds onto the active side of that enzyme to form the intermediate molecule, the enzyme substrate complex. Now, once we form the enzyme substrate complex, one of two things can take place.