Carbaminohemoglobin (CO2Hb)

Carbaminohemoglobin is a compound of haemoglobin and carbon dioxide, and is one of the forms in which carbon dioxide exists in the blood. 10% of carbon dioxide is carried in blood this way. The nature of carbon dioxide's binding to hemoglobin to form carbaminohaemoglobin is not always agreed upon by biochemistry texts. Four molecules of oxygen can bind to one molecule of haemoglobin. It is suggested by some that haemoglobin can also bind to four molecules of carbon dioxide. Among those who share this belief, it is generally agreed that each molecule of carbon dioxide must bind to a region on the heme monomer which a molecule of oxygen would not typically use. Other biochemistry texts claim that carbon dioxide does not bind to the haemoglobin tetramer at all and can only be found floating in the cytoplasm of the red blood cells. Research is currently being conducted in order to ascertain the truth of the matter.