Ceruloplasmin (CP)

Ceruloplasmin is is the major copper-carrying protein in the blood, and in addition plays a role in iron metabolism. It was first described in 1948.  It is an enzyme (EC 1.16.3.1) synthesized in the liver containing 6 atoms of copper in its structure. Ceruloplasmin carries 90% of the copper in plasma. The other 10% is carried by albumin, albumin may be confused at times to have a greater importance as a copper carrier because it binds copper less tightly than ceruloplasmin. Ceruloplasmin exhibits a copper-dependent oxidase activity, which is associated with possible oxidation of Fe2 (ferrous iron) into Fe3 (ferric iron), therefore assisting in its transport in the plasma in association with transferrin, which can only carry iron in the ferric state. The molecular weight of human ceruloplasmin is reported to be 151kDa.