Now let's move on to the third important fact about enzymes. So, biological enzymes, biological catalysts do not change the energy of the products, nor do they actually change the energy of our reactants. And that means the change in enthalpy or the change in Gibbs free energy of the overall reaction does not exactly change. So, to see what we mean, let's take a look at the following two graphs, which are basically these graphs here. So notice that we have the reactants and the products. So this line is the energy for the reactants.