Ceruloplasmin (human plasma)

Serum copper transport and iron-oxidizing protein. Expressed in plasma at concentrations of 1-5µM. Contains six copper centers and is known to oxidize amines in a process coupled to the reduction of molecular oxygen. Has ferroxidase activity that is responsible for the oxidation of ferrous iron to its ferric form, which is necessary for efficient iron efflux from the cell (e.g. during hypoxia). Has previously been considered a target for nitric oxide (NO) and an inhibitor of endothelial nitric oxide synthase (eNOS/NOS III). Catalyzes S-nitrosothiol formation in cell culture media. Is a NO oxidase and nitrite synthase that determines endocrine NO homeostasis.