And when they combine, when the substrate combines into the active side of the enzyme, we form the enzyme substrate complex Es and K. One is the rate constant of this reaction. Now, once we form this complex, there are two ways that this complex can basically dissociate the substrate. If it is not bound very strongly to that active side, it can simply dissociate and leave the active side without actually being transformed into the product. And this simply means it goes back to reform these two reactants in a rate constant. That case is K minus one. But if the substrate is bound strongly to the active side, that active side will be able to catalyze and transform that substrate into the product.