So let's suppose the oxalo acetate binds into the active side that induces a conformational change that then allows that acetyl coenzymen to bind into the active side. And so now we have this diagram. So in step one, what takes place is we ultimately want to form an enol intermediate. And remember, the enol form of this molecule contains a hydroxyl group here and a double bond between this carbon and this carbon. So remember from organic chemistry that whenever we have an aldol condensation reaction, we essentially have an enorm intermediate molecule. And so, to essentially stimulate the formation of this enormous molecule that will act as a nucleophile that will help form the citrull coenzyme A, we see that these enzymes, or I should say these catalytic residues of the enzyme, actually help with this process.