So the entire point of step four is to create a molecule with a greater phosphoryl transfer potential. So in the step number four, an enzyme called Nalase converts the two phosphoglycerate that was formed in this step three into a phosphoenyl Pyruvate or Pet. So this is the reaction shown here. So we begin with the same molecule. And now we basically label this H atom and this oh group. And we also label this bond here, because what happens is we have a dehydration reaction that is catalyzed by the enolase.