Hemoglobin

Hemoglobin or haemoglobin (frequently abbreviated as Hb, {{PDB|1A3N}}) is the iron-containing oxygen-transport metalloprotein in the red cells of the blood in mammals and other animals. The molecule consists of globin, the apoprotein, and four heme (or haem) groups, which are organic molecules with an iron atom in each.

Other biological oxygen-binding proteins

It should be noted that hemoglobin is by no means unique. There are a variety of oxygen transport and binding proteins throughout the animal (and plant) kingdom. Other organisms including bacteria, protozoans and fungi all have hemoglobin like proteins, their known and predicted roles include the reversible binding of gaseous ligands.

Related Topics:
Bacteria - Protozoa - Fungi - Ligand

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Myoglobin: Found in the muscle tissue of many vertebrates including humans (gives muscle tissue a distinct red or dark gray color). Is very similar to hemoglobin in structure and sequence, but is not arranged in tetramers, it is a monomer and lacks cooperative binding and is used to store oxygen rather than transport it.

Related Topics:
Myoglobin - Cooperative binding

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Hemocyanin: Second most common oxygen transporting protein found in nature. Found in the blood of many arthropods and molluscs. Uses copper prosthetic group instead of iron heme groups and is blue in color when oxygenated.

Related Topics:
Hemocyanin - Arthropod - Mollusc

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Hemerythrin: Some marine invertebrates and a few species of annelid use this iron containing non-heme protein to carry oxygen in their blood. Appears pink/violet when oxygenated, clear when not.

Related Topics:
Hemerythrin - Annelid

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Vanabins: also known as Vanadium Chromagen are found in the blood of Sea squirt and are hypothesised to use the rare metal Vanadium as its oxygen binding prosthetic group, but this hypothesis is unconfirmed.

Related Topics:
Vanabins - Vanadium - Sea squirt

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Erythrocruorin: found in many annelids, including earthworms. Giant free-floating blood protein, contains many dozens even hundreds of Iron heme containing protein subunits bound together into a single protein complex with a molecular masses greater than 3.5 million daltons.

Related Topics:
Annelid - Earthworm

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Pinnaglobin: Only seen in the mollusk Pinna squamosa. Brown manganese-based porphyrin protein.

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Leghemoglobin: In leguminous plants, such as alfalfa or soybeans, the nitrogen fixing bacteria in the roots are protected from oxygen by this iron heme containing, oxygen binding protein.

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