Yes. Carbon dioxide (CO2) and carbon monoxide (CO) also bind to hemoglobin. Hemoglobin, when saturated with oxygen, is called oxyhemoglobin. It is cherry red in color. When oxyhemoglobin loses its oxygen, it becomes bluish purple. Hemoglobin in combination with carbon dioxide is called carbaminohemoglobin. Oxygen and carbon dioxide have distinct carry sites on the Hb molecule. Carbon monoxidecombined with Hb is called carboxyhemoglobin. Carbonmonoxide binds to a heme and has 200 times the affinity for the heme that oxygen has. It is this competitive exclusion of oxygen that makes carbon monoxide so dangerous a gas.
