Perspectives on copper biochemistry.

The biochemistry of the essential trace element copper has been outlined. Following absorption, Cu(II) is transported by serum albumin and transcuprein to the liver where it is incorporated into the plasma Cu-protein, ceruloplasmin, or, possibly, stored as Cu-metallothionein or as superoxide dismutase. Ceruloplasmin is the long-term copper transporter and carries Cu(II) to the tissues for the biosynthesis of key Cu(II) enzymes, especially cytochrome c oxidase, lysyl oxidase and others. The production of copper enzymes raises many new questions about the metabolism of copper. Since ceruloplasmin is the centerpiece of copper metabolism and function, we conclude with more details on its chemistry and multifunctions. This Cu-protein of 132,000 daltons has now been totally sequenced and the copper-containing active sites located. Finally, we have proposed seven possible functions for ceruloplasmin, and there is now good evidence for the existence of ceruloplasmin receptors to expedite some of these functions.