Erythrocruorin

Erythrocruorin is a type of oxygen-carrying protein found in the blood of certain invertebrates, including many annelids and some arthropods. It is a giant extracellular hemoglobin that can be up to 3.6 million daltons in size, making it one of the largest known proteins.

Structure

Erythrocruorin is a complex of multiple subunits, each of which is a globin molecule. These subunits are arranged in a hexagonal pattern, forming a large, spherical structure. Each subunit can bind to one molecule of oxygen, allowing erythrocruorin to carry a large amount of oxygen relative to its size.

Function

The primary function of erythrocruorin is to transport oxygen from the respiratory system to the cells of the body. It does this by binding to oxygen in the lungs or gills, and then releasing it in the tissues where it is needed. This is similar to the function of hemoglobin in vertebrates, but erythrocruorin is able to carry a larger amount of oxygen due to its larger size and complex structure.

Distribution

Erythrocruorin is found in a variety of invertebrate species, including many annelids and some arthropods. It is particularly common in species that live in low-oxygen environments, such as deep-sea worms and insects that live in stagnant water.

See also

• Hemoglobin
• Myoglobin
• Hemocyanin

References

• 
  Erythrocruorin structure at 3.5 Å resolution
• 
  Chlorocruorin ligand structure