Hemoglobin is a complex protein that is localized in erythrocytes and transports oxygen and carbon dioxide in the blood. There are several forms of this protein; one of these forms, hemoglobin A, which is found in adult humans, is composed of four polypeptide chains, (two α-chains and two β-chains) each with a heme group containing an iron atom [1].

Ligand binding to the heme sites in the hemoglobin protein does not occur simultaneously. For example, the addition of the first oxygen molecule causes conformational changes in the protein that facilitate the rapid acquisition of the remaining oxygen molecules. In an environment with a high level of carbon dioxide, hemoglobin releases its bound oxygen. When the first oxygen molecule is disengaged, the hemoglobin begins to change its shape releasing the other three oxygen molecules. In addition to the oxygen in carbon dioxide, hemoglobin binds and transports nitric oxide, carbon monooxide and several other inorganic compounds [2, 3]. Hemoglobin is a well-studied protein that was discovered by the German physiologist Otto Funke in 1851, and its structure was first described in 1959 by the Austrian molecular biologist Max Perutz, who later received the Nobel Prize in chemistry for his work [4].

Date: Feb 08, 2010


  1. Liddington R. et al., J Mol Biol. 1992 Nov 20;228(2):551-79.
  2. Chan N.L. et al., Biochemistry. 1998 Nov 24;37(47):16459-64.
  3. Baldwin J.M., J Mol Biol. 1980 Jan 15;136(2):103-28.
  4. Perutz M.F., Nature. 1960 Feb 13;185(4711):416-22.