Hemoglobin, the most crucial oxygen-carrying molecule in red blood cells, carries equally oxygen and carbon dioxide. However, the CO2 bound to hemoglobin isn't going to bind to the same web site as oxygen. Rather, it combines with the N-terminal groups to the 4 globin chains. Nonetheless, thanks to allosteric https://www.youtube.com/watch?v=buIHtQY7fCU