Hemoglobin (Hb) (Hb)

Hemoglobin (Hb) is a metalloprotein in red blood cells composed of four subunits, each with an iron-containing heme group that reversibly binds up to four oxygen molecules, enabling transport from lungs to tissues for ATP production via oxidative phosphorylation. It also facilitates carbon dioxide return to lungs and nitric oxide transport for vascular control, with unloading regulated by factors like pH, temperature, and 2,3-BPG concentration via the Bohr effect and cooperative binding shown in its sigmoidal dissociation curve. Dysfunctions like anemia or sickle cell disease impair oxygen delivery, causing hypoxia and tissue damage, while carbon monoxide toxicity blocks heme sites. Artificial mimics such as HBOCs aim to substitute in transfusions but face challenges including vasoconstriction; hemoglobin remains essential for aerobic life across vertebrates.

Other names

HaemoglobinHgbOxygen transporterRed blood cell oxygen carrier

HBOCs bind and release oxygen reversibly like natural hemoglobin to improve tissue oxygenation; Perfluorocarbons dissolve high quantities of oxygen for delivery as red blood cell substitutes; Used to avoid or reduce allogeneic blood transfusions.