In which form does copper exist predominantly in human blood?

Copper predominantly exists in human blood in the form bound to ceruloplasmin. Ceruloplasmin is a copper-carrying protein that plays a crucial role in transporting copper through the bloodstream and facilitating its proper utilization in the body. This binding to ceruloplasmin not only helps in solubilizing copper for transport but also plays a role in its bioavailability and functionality, particularly in various enzymatic reactions that involve copper.

While some copper can exist in other forms, such as in a free ionic state or associated with different proteins, the predominant form is indeed bound to ceruloplasmin. This primarily ensures that copper is delivered to tissues that require it for various biological processes, including iron metabolism and antioxidant defense. The other forms mentioned are present to a lesser extent and do not play as significant a role in copper transport in the bloodstream.