Figure 1.

Red blood cells are degraded into hemoglobin (Hb) during cell turnover or damage. Hb further catabolizes to globin chains, which are broken into amino acids and heme. Heme oxygenase catabolizes the heme to yield ferrous iron, which will later travel to bone marrow to be used in new heme production, carbon monoxide, and biliverdin (Bv). Bv is then reduced to an unconjugated form of bilirubin (Bu). All of these degraded components can be present in inflammatory responses related to hemolysis, and each can maintain a unique contribution to the inflammatory reaction. The balanced reaction above is based on Hb with its heme iron in the ferrous state. The molecular image of Hb was generated using PyMol (Version 2, Schrodinger, LLC, Delano Scientific, San Carlos, CA, USA). Similar images of Heme, Bv, and Bu are available through ChemSpider online search and share chemistry, Royal Society of Chemistry, Cambridge, UK.