ЦЕРУЛОПЛАЗМИН, ЧЕЛОВЕКА

A copper-containing alpha globulin in blood plasma that contains type 1, type 2, and type 3 copper cen- ters in which the type 2 and type 3 centers are near each other, constituting a trinuclear copper cluster. It may play a part in red blood cell production and oxygen reduction.

Typically, 50% of the daily copper intake is absorbed in theGI tract and transported to the liver from where it is transported to the peripheral tissue bound to ceruloplasmin, acopper-binding glycoprotein. A smaller amount of copper is also bound to albumin. Excess copper is mainly excreted in bile into the gut and then the faeces.
Ceruloplasmin (ferroxidase I) and ferroxidase II, two copper-based enzymes, can oxidise ferrous iron to ferric iron. Ferric iron can then be transported with the help of transferrin,for example, to form red blood cells. Furthermore, a variety of copper-dependent enzymes, such as cytochrome c and superoxide dismutase, work as antioxidants and are involved in the reduction of reactive oxygen species (ROS).
Cancer progression has been linked to increased ceruloplasmin and copper levels in a variety of tissues.Copper deficiency has been considered as an anticancer strategy, but several clinical studies have not been encouraging.

Ceruloplasmin (Cp), the principal carrier of copper in plasma, is thought to be involved in oxidative modification of lipoproteins and participate in the acute phase reaction to stress. Cp is an effective antioxidant for a variety of radicals and has a potent peroxidase activity to decompose hydrogen peroxide in the presence of reduced glutathione. It inhibits the peroxidase activity of myeloperoxidase in a concentration-dependent manner and shows selective binding to myeloperoxidase in vitro. This suggests that ceruloplasmin may participate in the clearance and inactivation of myeloperoxidase in vivo. At physiological (micromolar) concentrations it was found to inhibit relaxation of rabbit aorta induced by endothelium-dependent agonists like acetylcholine or ADP. However, it was found ineffective toward vasodilation due to direct stimulation of smooth muscle cells by nitroglycerin. Cp plays an essential role in iron homeostasis, regulating the efflux of iron from macrophages and the oxidation of Fe2+ to Fe3+. Cp deficiency leads to neurodegenerative disorders, possibly by starving neurons of iron.