Hemoglobin Allostery Hemoglobin Allostery Hemoglobin is the oxygen carrier in the blood. Hemoglobin is a protein made up of four chains - two alpha and two beta chains. Each one of the chains carries a non-covalently bound heme group that binds oxygen. Alpha Chains are in red and beta chains in green. Figure 2 .The Heme group.
Carbon atoms are colored white, oxygens in red, nitrogens in blue and iron golden.
Each heme group can bind one oxygen molecule. Thus, the hemoglobin tetramer can bind a total of four oxygen molecules. Hemoglobin also serves the purpose of transporting carbon dioxide . Oxygen is bound by hemoglobin at the lungs, carried through the blood stream to various tissues, where it gives up the oxygen, and binds carbon dioxide and transports it back to the lungs. Carbon dioxide is bound as the bicarbonate ion, HCO 3 - , at the dimer interface and not to the heme.