heme

(noun)

the component of hemoglobin responsible for binding oxygen; consists of an iron ion that binds oxygen and a porphyrin ring that binds the globin molecules; one molecule binds one molecule of oxygen

Related Terms

  • sickle cell anaemia
  • haem
  • sickle cell anemia
  • thalassemia

Examples of heme in the following topics:

  • Electron Transport Chain

    • Cytochrome proteins have a prosthetic heme group.
    • The heme molecule is similar to the heme in hemoglobin, but it carries electrons, not oxygen.
    • The heme molecules in the cytochromes have slightly different characteristics due to the effects of the different proteins binding them, which makes each complex.
    • This complex contains two heme groups (one in each of the cytochromes a and a3) and three copper ions (a pair of CuA and one CuB in cytochrome a3).
  • Transport of Oxygen in the Blood

    • Each subunit surrounds a central heme group that contains iron and binds one oxygen molecule, allowing each hemoglobin molecule to bind four oxygen molecules.
    • Molecules with more oxygen bound to the heme groups are brighter red.
    • Hemoglobin is made up of four symmetrical subunits and four heme groups.
    • Iron associated with the heme binds oxygen.
  • Red Blood Cells

    • Despite the name, hemerythrin does not contain a heme group; its oxygen-carrying capacity is poor compared to hemoglobin.
    • Hemoglobin is composed of four protein subunits, two alpha chains and two beta chains, and a heme group that has iron associated with it.
    • Like hemoglobin, hemerythrin is carried in blood cells and has iron associated with it, but despite its name, hemerythrin does not contain heme.
  • Types and Functions of Proteins

    • For instance, the blood protein hemogobin is made up of four polypeptide chains, each of which also contains a heme molecule, which is ring structure with an iron atom in its center.
    • The proteins' α and β subunits are in red and blue, and the iron-containing heme groups in green.
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