Blood plasma amino acids copper complexes

Much of the copper in the plasma (60-95%) is bound to ceruloplasmin. The complex of copper and cenjloplasmir is assembled and secreted by the liver. A small fraction of plasma copper, under 7%, is weakly bound to albumin and to free amino acids, especially histidine, threonine, and glutamine. The copper bound to serum albumin is associated with a histidine residue near the amino terminus of the protein. The copper in red blood cells is bound to superoxide dismutase. 

Plasma copper exists in two forms 5% is loosely bound to albumin, and the remainder exists in the form of copper complexes. Copper forms ionic bonds with either an imidazole or a carboxyl group of the amino acid of albumin. Loosely bound copper reacts readily with dithiocarbamate, and therefore has been called the directly reacting copper. It is generally assumed but not established that the albumin that binds this copper plays an important role in transporting copper in the blood. 

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