What is the role of ceruloplasmin in the serum?

Ceruloplasmin is a copper-carrying protein in the blood that is crucial for iron metabolism and the transport of copper. It plays a significant role in transporting the majority of copper in the serum, maintaining copper homeostasis and helping to prevent copper toxicity.

Ceruloplasmin also has oxidase activity, which is responsible for converting ferrous iron (Fe2+) to ferric iron (Fe3+). This function is vital in iron metabolism because ferric iron binds to transferrin, the primary iron transport protein in the serum. Therefore, while ceruloplasmin is involved in iron metabolism, its primary function and significance lie in copper transport.

Other choices do not accurately describe ceruloplasmin's primary role, which is specifically associated with binding copper rather than iron or other substances.