Copper in the body

Copper is an essential trace metal for all living beings. However, although copper is indispensable for many physiological functions of human organism, the presence of excess amount of copper in the body may be toxic. One possible source of copper in human body that is scarcely investigated is dental materials. 

Copper is an essential trace element. It is required in the diet because it is the metal cofactor for a variety of enzymes (see Table 50—5). Copper accepts and donates electrons and is involved in reactions involving dismu-tation, hydroxylation, and oxygenation. However, excess copper can cause problems because it can oxidize proteins and hpids, bind to nucleic acids, and enhance the production of free radicals. It is thus important to have mechanisms that will maintain the amount of copper in the body within normal hmits. The body of the normal adult contains about 100 mg of copper, located mostly in bone, liver, kidney, and muscle. The daily intake of copper is about 2—A mg, with about 50% being absorbed in the stomach and upper small intestine and the remainder excreted in the feces. Copper is carried to the liver bound to albumin, taken up by liver cells, and part of it is excreted in the bile. Copper also leaves the liver attached to ceruloplasmin, which is synthesized in that organ. 

Despite the positive effects of optimal levels of copper, deleterious effects may occur if a threshold level is exceeded. Wilson s disease (hepatolenticularic degeneration) is one of the diseases linked to the excess of copper in the body. It results from a dysfunction of the copper transmission process, which occurs due to a lack of suitable enzyme to catalyze the process of copper deletion from detached bonds with albumins and binding to ceruloplasma. The condition leads to neuron degradation, liver cirrhosis, and occurrence of colorful rings on the cornea (DiDonato and Sarkar, 1997). 

If One had to state an overall role of copper in the body, one might say oxygen metabolism. One major factor shared by both zinc and copper is that both metal ions occur bound to metal loth tonein. The function of melallothioncin is not fitmlv... 

If one had to state an overall role of copper in the body, one might say oxygen metabolism. One major factor shared by both zinc and copper is that both metal ions occur bound to metallothionein. The function of metallothionein is not firmly established. Copper is bound to another protein, ceruloplasmin, which occurs in the cell and plasma. The function of this protein is not clear either. Zinc absorption, as iron absorption, is impaired by high levels of phytic acid. Copper absorption is not inhibited by phytic acid. The major route of excretion of both metal ions is fecal, rather than urinary. 

Ceruloplasmin, first reported by Holmberg and Laurrell (47), is a copper-alpha-2-globulin. It comprises about 95% of the total copper body pool and is released only when the protein molecule is catabolized. This fraction of copper is in an exchangeable equilibrium with the ionic form the remainder is loosely bound to albumin (48) and to amino acids (49). This last fraction recently has been reported to play a major role in transporting copper in the body. 

Returning now to the distribution of copper in the body, a large percentage of the copper which rapidly disappears from the blood is taken up by the liver. Bush et al. (B32) were the first to discover the concentration of activity in the liver following administration of radiocopper. Osborne et al. (01, 04) in control human subjects found 66-95% of an intravenously injected 30-300-/ig dose of copper in the liver 2-8 hours following injection. Results of a similar study (S8) in a control individual are shown in Fig. 3. The lower part of the graph shows that 86% of the intravenous 1-mg dose of copper was concentrated in the liver 4 hours after its administration. Thereafter, activity over the liver declined, a phenomenon also noted earlier by Osborne and Walshe (01). 

The availability of copper in the body is somewhat different from that of iron. Copper in the Mood serum is bound in caeruloplasmin, Excessive dietary copper is predominately carried by serum albumin. Serum albumin copper is in the equilibrium with low molecular mass complexes of amino acids or small peptides. Unfortunately, the concentration of such complexes is below the detection limit. Regardless of the... 

The copper present in the plasma is used to synthesize copper proteins in practically all tissues. Kidney, brain, and liver seem to be particularly rich in copper on a weight basis. However, because of their mass, skeleton and muscle contain about 50% of the total copper in the body. 

What are the roles of selenium, chromium, and copper in the body ... 

Treatment is directed towards reducing the amount of copper in the body [4, 5]. Measuring urinary copper and zinc can monitor the efficacy of chelation and/or zinc therapy. With adequate treatment the prognosis is good. In severe liver damage, liver transplantation might be necessary [5]. 

The amount of copper in the body is 80-100 mg. Copper is a component of a number of oxido-reductase enzymes (cytochrome oxidase, superoxide dismutase, tyrosinase, uricase, amine oxidase). In blood plasma, it is bound to ceruloplasmin, which catalyzes the oxidation of Fe + to Fe +. This reaction is of great significance since it is only the Fe + form in blood which is transported by the transferrin protein to the iron pool in the liver. The daily copper requirement is 1-1.5 mg and it is supplied in a normal diet. Copper is even less desirable than iron during food processing and storage since it catalyzes many unwanted reactions. Cu +-Ions are taste bearing. The threshold value 2.4-3.8 mg/1 was determined with aqueous solutions of CuSOa or CuCl2. 

The average concentration of copper in blood is 1.10 mg/1 in men and 1.23 mg/I in women. More than 90% of copper in the body is found in the blood plasma. The major copper-binding substance in blood plasma is monomeric glycometaUoprotein ceruloplasmin from a group of a2-globulins (132 kDa), which is composed of 1046 amino acids and contains about 7-8% of sugar components. Ceruloplasmin has a blue colour and in the normal state one molecule of ceruloplasmin contains six atoms of copper (at full saturation additional binding sites may be occupied by an additional two copper atoms). Blood plasma contains about 300 mg/1 of ceruloplasmin. In erythrocytes, copper occurs in another protein called erythrocuprein (31 kDa) and in the enzyme superoxide dismutase. 

---