Structure and Significance of Hemocyanin
Hemocyanins are proteins that transport oxygen throughout the bodies of some invertebrate animals. These metalloproteins contain two copper atoms that reversibly bind a Unlike the hemoglobin in red blood cells found in vertebrates, hemocyanins are not bound to blood cells but are instead suspended directly in the hemolymph. Oxygenation causes a color change between the colorless Cu(I) deoxygenated and the blue Cu(II) oxygenated form.
The respiratory function of hemocyanin is similar to that of hemoglobin, there are a significant number of differences in its molecular structure and mechanism. Whereas hemoglobin carries its iron atoms in porphyrin rings (hemegroups), the copper atoms of hemocyanin are bound as prosthetic groups coordinated by histidine residues.
Most hemocyanins bind with oxygen non-cooperatively and are roughly one-fourth as efficient as hemoglobin at transporting oxygen per amount of blood.
Hemoglobin binds oxygen cooperatively due to steric conformation changes in the protein complex,Hemocyanin is made of many individual subunit proteins, each of which contains two copper atoms and can bind one oxygen molecule (O2).. The subunits are usually homogeneous, or heterogeneous with two variant subunit types. Because of the large size of hemocyanin, it is usually found free-floating in the blood, unlike hemoglobinHexamers are characteristic of arthropod hemocyanins.. A hemocyanin from the house centipede Scutigera coleoptrat is made up of 6 hexamers or 36 chains. Peptide chains in crustaceans are about 660 amino acid residues long, In the large complexes there is a variety of variant chains, all about the same length.
Anti Cancer Effects
Concholepas hemocyanin showed antitumor effects: prolonged survival, decreased tumor growth and incidence, and lack of toxic effects and may have a potential use in future immunotherapy for superficial bladder cancer.
Megathura crenulata. has been shown to be a significant treatment against the proliferations of breast cancer, pancreas cancer, and prostate cancer cells when delivered in vitro. esophageal cancer through both apoptic and nonapoptic mechanisms of cell death.
By – Assistant Professor – Mr. Ranjeet Kumar Jha
Chemistry Department
Uttaranchal (P.G.) College Of Bio-Medical Sciences & Hospital