Confirmation. Why? Well, remember in our discussion of glucose molecules and sugar molecules. We said that when the sugar molecules exist in their cyclic form, they do not typically undergo any reactions because that aldehyde group or the ketone group is not actually exposed. And so what happens is a special enzyme known as phosphorglucose isomerase opens up this structure to form the open chain, confirmation now that exposes this reactive aldehyde group. In the next step, we basically catalyze the transformation of this glucose in its open chain into a fructose in the open chain.