Ceruloplasmin copper content

Ceruloplasmin (about 160 kDa) is an a2-globulin. It has a blue color because of its high copper content and... 

Wilson s disease Autosommal recessive, low serum ceruloplasmin and increased hepatic copper content. 

The number and type of copper centers, EPR parameters, and the two relevant absorption bands in the visible region for several representative members of the blue oxidases are listed in Table II. All laccases except that of the P. radiata enzyme contain four coppers per molecule with one type-1, one type-2, and one type-3 copper center. The EPR and absorption parameters resemble each other very much. Phlebia radiata laccase is supposed to contain only two coppers with one type 1, one type 2, and one PQQ per mole (70). This is quite unusual and will be discussed critically below, since it is possible that the copper content determined for this enzyme is inaccurate. Ascorbate oxidases have eight coppers per homodimer with two type-1, two type-2, and two type-3 copper centers. Ceruloplasmin typically contains six to seven copper ions per molecule with three type-1, one type-2, and one type-3 copper centers. It has also been proposed that there are only two type-1 copper ions and a new type-4 copper that is presumed to exhibit no EPR signal. In addition there is a variable content of chelatable copper. It is responsible for copper contents exceeding 6 coppers/mol but does not seem to be required for catalysis. It is now generally accepted that ceruloplasmin has three type-1 copper centers and the reason for this will be discussed below. 

Confirmation The diagnosis is verified by laboratory parameters (determination of the serum values of copper and ceruloplasmin as well as of copper excretion in the urine, if necessary also by means of the penicillamine test) and by demonstration of the copper content of the liver, with simultaneous differentiation of existing liver damage. 

Wilson s disease is an autosomal recessive disease of copper metabolism. It has a prevalence of 1 in 30,000 live births in most populations. The disease has a highly variable clinical presentation. It is characterized by impairment of biliary copper excretion, decreased incorporation of copper into ceruloplasmin, and accumulation of copper in the liver and, eventually, in the brain and other tissues. The biochemical findings include low serum ceruloplasmin, high urinary copper excretion, and high hepatic copper content. Some patients have normal serum cerulo-plasmia levels, and heterozygous individuals do not consistently show reduced levels of this protein. 

Low serum ceruloplasmin levels, if present, are a constant feature of the disease. Very low levels have been found in completely asymptomatic patients as early as infancy (H3). The author has investigated two completely asymptomatic patients with Wilson s disease (3 and 21 years of age) and found very low serum ceruloplasmin and reduced serum copper levels. Asymptomatic patients similarly to the symptomatic ones show no evidence of incorporation of Cu into the ceruloplasmin. The copper content of the... 

In summary, reported results contribute to an understanding of altered copper metabolism associated with RA and osteoarthritis and its patterning in these and other degenerative diseases [113], Marked increases in serum copper were confirmed in patients with early active disease. The observed alteration in serum copper is now understood as being mediated by interleukin-1 [29]. The increased rate of synthesis and accelerated turnover-rate of Cp was found to be directly related to disease activity. Synovial fluid copper content was found to increase in RA and osteoarthritis. Ceruloplasmin, which accounted for most of the SF copper increase, was found to increase with increasing duration of disease. 

The laboratory diagnosis of Wilson s disease is confirmed by decreased serum ceruloplasmin, increased urinary copper content, and elevated hepatic copper concentration. In most cases, a liver biopsy will be warranted to obtain an accurate measurement of hepatic copper, that will be elevated even in asymptomatic patients. Witt et al. (2001) recently described a DNA-based method for rapid determination of the H1069Q mutation in the ATP7B gene. 

Copper content of biological materials is determined by dicyclohexanoneoxalyldihydrazone (DCO) through a procedure which is a combination and modification of two frequently used methods in the literature [27,28]. The estimation is carried out by spectrophotometric measurement at 600 nm. As has been discussed previously, ceruloplasmin level in serum provides an important diagnostic feature of Wilson s and Menkes s diseases. This copper-containing metallopiotein in plasma can catalyze the oxidation of p-phenylenediamine (PPD) [29], The rate at which PPD is oxidized is proportional to the concentration of ceruloplasmin in serum. Under precisely defined conditions of composition of the medium, and at a given temperature, the rate of oxidation allows the calculation of the concentration of enzyme in the serum. 

Lewis CD, Laemmli UK (1982) Higher order metaphase chromosome structure evidence for metalloprotein interactions. Cell 29 171-181 Li NQ, Reddy PS, Thyagaraju K, Reddy AP, Hsu BL, Scholz RW, Tu CP, Reddy CC (1990) Elevation of rat liver mRNA for selenium-dependent glutathione peroxidase by selenium deficiency. J Biol Chem 265 108-113 McArdle HJ, Mercer JF, Sargeson AM, Danks DM (1990) Effects of cellular copper content on copper uptake and metallothionein and ceruloplasmin mRNA levels in mouse hepatocytes. J Nutr 120 1370-1375... 

Dietary copper does not seem to be important in either disease, except possibly when anemia is present. Probably this means that the intake of copper is sufficient imder our present circumstances. The copper content of the serum, however, is very important in both diseases. There is some evidence that the serum protein to which nearly all the copper is bound, the ceruloplasmin, plays the piimaiy role (see below). 

As with all antiarthritic drugs, the situation is not clear. Biochemical effects of copper are general, and no one target, such as a particular protein, is recognizable. The copper complexes are presumably a means of further increasing the copper content, because the species are expected to be rather labile. The introduction of exogenous copper will also affect thiol content and redox state of the cell, and some biochemical responses listed above may be a consequence of this altered state. Besides ceruloplasmin and albumin, major binding sites of Cu(II) are histidine and cysteine [94, 95] and some possibilities for the mechanism of action have been summarized [64]. 

Recent publications signal the continued interest in the function of this protein. It has been called a stress enzyme, involved in influenza virus infection (Tomas and Toparceanu, 1986). An explanation for Wilson s disease in terms of a genetic defect resulting in failure to convert from a neonatal (i.e., low) level of ceruloplasmin and copper to a normal adult level has been reported (Srai et al., 1986). Tissue specificity for the binding of ceruloplasmin to membranes was demonstrated in a study investigating the possible role of ceruloplasmin-specific receptors in the transfer of copper from ceruloplasmin to other copper-containing proteins (Orena et al, 1986). Ceruloplasmin has been shown to be effective in transferring copper to Cu,Zn-SOD in culture (Dameron and Harris, 1987), as has copper albumin. In view of the variable content of copper in this protein, it is not clear which copper is transferred. 

A word of comment on the high Cu64 content of the bile seems justifiable, since the exact chemical form of copper excreted in the bile has not been determined. The possibility that ceruloplasmin or some copper-containing metabolite of ceruloplasmin is normally excreted in the bile has not been carefully examined. The abnormal elevation of the serum ceruloplasmin level in acute biliary obstruction (7), and the abnormally low serum ceruloplasmin seen in some cases of advanced liver disease, particularly Wilson s disease (2, 3), are in keeping with the liver being the site of ceruloplasmin synthesis and excretion. 

Copper is an essential trace element absorbed in the gut and transported to the liver bound to albumin. It is found in a variety of enzymes, including superoxide dismutase. In the bloodstream Cu is present mostly in ceruloplasmin. Tissues with a relatively high content of Cu are liver, heart, and brain. The RDA for Cu in normal, healthy adults is 0.9 mg day-1, but newborns usually have liver levels higher than those of adults. The concentration of Cu in mature milk ranges between 0.2 and 0.3 mg l-1 in colostrum it is higher (0.4-0.6 mg l-1), but decreases along the lactation period (see the Chapter 13 by de la Flor St Remy et al.). 

The disease is a rare inherited disorder characterized by a progressive degeneration of the lenticular nucleus in the brain and by cirrhosis of the liver. Barbeau et al. (Bl) studied a case of Wilson s disease which presented normal ceruloplasmin and serum copper values but increased excretion of kynurenine, 3-hydroxykynurenine, and conjugated anthra-nilic acid in xurine after an oral dose of 2 g L-tryptophan. This defect in tryptophan metabolism could be related to that of other amino acids and to the actual content of ceruloplasmin in Wilson s disease (Bl). These findings corroborated Marver s (M2) investigations demonstrating a definite excretion of kynurenine and 3-hydroxykynurenine in abnormal proportions after a tryptophan load in a case of Wilson s disease. 

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