So this nitrogen is protonated to form this bond here. And this allows us to form sold bridges, which are stabilizing electric interaction with the nearby Aspartate side chain. This sold bridge stabilizes the t state of the deoxy hemoglobin, thereby lowering its affinity for oxygen and allowing to unload more of the oxygen to the tissue. So this is our stabilizing salt bridge. It's called a salt bridge because we have a partial positive charge and a partial negative charge on this side. So this is how the PH effect actually creates or allows the hemoglobin to unload more oxygen.