ceruloplasmin) CP Copper-binding (6-7 atoms per molecule) glycoprotein with ferroxidase
activity oxidizing Fe(2+) to Fe(3+) without releasing radical oxygen species.
Among the minerals required for skeletal formation, colloidal system maintenance, acid--base balance, and enzyme activities, Cu has been considered increasingly important in crustacean nutrition because of its functions in hematopoiesis and in numerous Cu-dependent enzymes including lysyl oxidase, cytochrome c oxidase, ferroxidase
, tyrosinase, and superoxide dismutase (SOD) (Lall 2002).
We previously developed an immunoassay for CP, a ferroxidase
that plays a role in copper and iron metabolism, and characterized the antibody pair for this blood protein (15).
More than 90% of copper is bound to ceruloplasmin, an [alpha]2-globulin with ferroxidase
Ceruloplasmin is an [alpha]2-glycoprotein synthesized in hepatocytes that binds plasma copper and has ferroxidase
It is remarkably similar to 1-I-ferritin that assembles into typical ferritin shells within mitochondria and has ferroxidase
CP also has an important role as a ferroxidase
and superoxide scavenger.
An important feature of H subunit is its ferroxidase
activity that facilitates the oxidation of Fe2+ (predominant form in the cytosol) to Fe3+ to be bound to ferritin.
Ceruloplasmin is a copper-dependent ferroxidase
that likely cooperates with ferroportin to export iron from macrophages, hepatocytes, and intestinal mucosal cells (Fig.
Ceruloplasmin has ferroxidase
activity as well as ferritin H subunits, and patients with a congenital absence of ceruloplasmin develop severe iron overload (17,18).
The H chain has ferroxidase
activity, whereas the L chain favors iron mineralization in the cavity.
2+] among other substrates (1), and the catalytic oxidation of ferrous ions or ferrous complexes to the ferric state by ceruloplasmin is termed as ferroxidase