Now, it's the second step of this overall process that drives the overall equilibrium of this process to the product side so that we can basically form the citrate molecules effectively and efficiently. And that's because the cleavage of this high energy bond is actually a very beneficial process because we don't want to have this high thio esther bond, this high in energy thio ester bond. So in this lecture, I'd like to focus on step one or actually the first process of step one. So the Aldol condensation reaction because this step is much more complicated than the simple hydrolysis step. So before we look at the reaction mechanism what actually takes place in the active side of the enzyme, let's discuss briefly this citrate synthase enzyme. So citrate synthase, the enzyme that catalyzes step one of the citric acid cycle is actually a dimer enzyme.