And that's precisely why when we go from no CO2 PH of 7.4 to no CO2 and a PH of 7.2 because we increase our h plus iron concentration, we essentially form these sold bridges. And that basically shifts the black curve to the blue position shown here. So once again, as the hydrogen ion concentration increases, the histidine side chain becomes protonated. 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.