Hemocyanin
| Hemocyanin, common lobster ( Palinurus vulgaris ) | ||
|---|---|---|
| Mass / length primary structure | 657 amino acids | |
| Secondary to quaternary structure | Homooligomer | |
| Cofactor | n Cu 2+ | |
| Identifier | ||
| External IDs | ||
| Occurrence | ||
| Parent taxon | Arthropods , molluscs | |
Hemocyanin (. Of gr heme , Blood and kyanos , sky blue ') is a blood pigment of arthropods (u a.. Crustaceans , arachnids , in insects , the trachea have, it occurs to a lesser extent) and mollusks (u a.. Mussels , snails and Cuttlefish ). It serves as an oxygen transporter .
In contrast to red, iron-containing hemoglobin , the oxygen in hemocyanin is bound by two copper ions. In addition, hemocyanin does not have a porphyrin structure like heme ; instead, the copper ions are bound to the protein via amino acid residues ( histidine ) . Oxygen-free hemocyanin is colorless; with bound oxygen it is blue.
The binding of oxygen is stronger than with hemoglobin. Compared to hemoglobin, however, hemocyanin has a lower oxygen binding capacity, which leads to an overall lower transport capacity for oxygen.
However, at very low temperatures, hemocyanin is superior to hemoglobin.
The mode of binding of the oxygen is also different from the iron-containing compounds hemoglobin and hemerythrin , in which the oxygen is bound end-on to an iron (II) ion. With hemocyanin, the oxygen is bridged between two copper (I) ions in a side-on coordination, which are oxidized to copper (II).
Hemocyanin, especially from mollusks, causes strong defensive reactions in the immune systems of mammals, but is completely non-toxic and is quickly broken down. It is therefore used as an adjuvant , but is also used in cancer therapy.
See also
- Slotted snail hemocyanin
- Hämerythrin , an iron-containing protein with a corresponding function.
Web links
- University Medical Center Hamburg-Eppendorf: Haemocyanins - the oxygen transporters ( Memento from March 17, 2004 in the Internet Archive )
- About the structure of hemocyanin (pages 6–7) (PDF file; 4.63 MB)
Individual evidence
- ↑ Search result UniProt hemocyanin family by taxonomy
- ↑ Entry on hemocyanin. In: Römpp Online . Georg Thieme Verlag, accessed on June 13, 2014.
- ↑ Michael Oellermann, Bernhard Lieb, Hans-O Pörtner, Jayson M Semmens, Felix C Mark: Blue blood on ice: modulated blood oxygen transport facilitates cold compensation and eurythermy in an Antarctic octopod . In: Frontiers in Zoology . tape 12 , no. 1 , March 2015, doi : 10.1186 / s12983-015-0097-x (English).
- ^ Karen A. Magnus, Hoa Ton-That, Joan E. Carpenter: Recent Structural Work on the Oxygen Transport Protein Hemocyanin. In: Chemical Reviews . 94, 1994, pp. 727-735, doi : 10.1021 / cr00027a009 .
- ↑ Markl J. Evolution of molluscan hemocyanin structures. Biochim Biophys Acta. 2013 ep; 1834 (9): 1840-52. doi : 10.1016 / j.bbapap.2013.02.020 .
- ^ JR Harris, J. Markl, Keyhole limpet hemocyanin (KLH): a biomedical review. Micron, 30 (1999), pp. 597-623