The carbon dioxide molecule is removed from the isocytrate, and we form this alpha ketoglutrate molecule. Now let's move on to step four. In step four, once again, we have another oxidative decarboxylation step. We're going to remove yet another carbon dioxide in the process abstracting the pair of high energy electrons to basically form the reduced NADH molecule, which eventually will be used by the electron transport chain to generate those high energy adenosine triphosphate molecules. And in this step, we actually use the coenzyme A, the same coenzyme A that we use in Pyruvate decarboxylation. So the next step is a second oxidative decarboxylation reaction of the citric acid cycle.