This implies that they will not change the equilibrium of the reaction. That is the same concentration of products and reactants will be formed in the presence as in the absence of the enzyme. So this is the case where we have our uncatalyzed reaction. But if we add an enzyme the energy value of the reactants and products will not actually change. Now, if the thermodynamics of the products and reactants is not changed by an enzyme, what is actually changed? Well, recall that the kinetics of the chemical reaction is determined by the energy of the transition state.