So if we place two phosphoryl groups in close proximity, that increases the energy of that molecule. And that's why the two three BPG is higher in energy than this molecule or this molecule. And so what that means is it's not going to exist for a very long time. It will either go back here and reform these reactants, or follow this pathway and form these products. So that same histidine then removes the phosphoryl group from the third carbon, forming that rearranged two phosphoglycerate molecules. So that's how this step actually takes place.