Extracellular Copper Substituents and Mammalian Copper Transport
At present, there are at least five major components of the blood plasma with which we know copper to be associated. These are ceruloplasmin, a fairly abundant α 2-glycoprotein, long recognized as containing the largest proportion of copper in most animal and human plasma; albumin, containing (except in the dog, pig, and chicken) a single high-affinity Cu-binding site at the N-terminus; two larger, nonceruloplasmin, nonalbumin proteins, one called ferroxidase II, and the other as yet less defined and named transcuprein; and a fraction of the plasma comprising small molecules (especially amino acids and small peptides), among which histidine may be the most important ligand. Other potential copper ligands include a histidine-rich glycoprotein and α 2-macroglobulin, both of which (like albumin) are also associated with zinc. It is thought that most of these components are present not just in plasma but also in interstitial fluid and in other fluids involved with copper transport, such as the cerebrospinal fluid in the brain (on the other side of the blood—brain barrier) and fluids in specialized areas (testes, amniotic fluid). This chapter reviews what is known about these components, their structure, properties, and potential function in copper transport.
KeywordsBlood Plasma Copper Atom Amine Oxidase Ascorbate Oxidase Copper Transport
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