Copper uptake

The P-alanyl dipeptides carnosine and anserine (A -methylcarnosine) (Figure 31-2) activate myosin ATPase, chelate copper, and enhance copper uptake. P-Alanyl-imidazole buffers the pH of anaerobically contracting skeletal muscle. Biosynthesis of carnosine is catalyzed by carnosine synthetase in a two-stage reaction that involves initial formation of an enzyme-bound acyl-adenylate of P-alanine and subsequent transfer of the P-alanyl moiety to L-histidine. 

Saccharomyces cerevisiae 85 copper uptake 290 iron storage 100 zinc uptake 295 scandium 108 selenium xvii... 

Bran, L.A., Maillet, J., Richarte, J., Herrmann, P. and Remy, J.C. (1998). Relationships between extractable copper, soil properties and copper uptake by wild plants in vineyard soils , Environmental Pollution, 102, 151-161. 

In addition, treatment with zinc acetate helps to reduce serum copper levels. Zinc acetate is a relatively nontoxic agent which blocks intestinal copper uptake and induces... 

Harland, A.D. and N.R. Nganro. 1990. Copper uptake by the sea anemone Anemonia viridis and the role of... 

Handy, R. D., Eddy, F. B. and Baines, H. (2002). Sodium-dependent copper uptake across epithelia a review of rationale with experimental evidence from gill and intestine, Biochim. Biophys. Acta-Biomembranes, 1566, 104—115. 

Gadd, G. M. and White, C. (1985). Copper uptake by Penicillium ochro-chloron influence of pH on toxicity and demonstration of energy-dependent copper influx using protoplasts, J. Gen. Microbiol., 131, 1875-1879. 

Figure 7.4 Copper uptake and release in E. hirae. The extracellular reductase CorA reduces Cu2+ to Cu+ for uptake by CopA. In conditions of copper excess CopB functions as a copper exporter. (From Solioz and Stoyanov, 2003. Reproduced with permission from Blackwell Publishing Ltd.)...

Because of their importance in many enzymes, bacteria have had to develop uptake systems for copper and zinc. Copper uptake (and homeostasis, which is discussed in Chapter 8) has been extensively studied in the Gram-positive bacterium Enterococcus hirae. Two of the genes in the cop operon, copA and copB, encode membrane ATPases. An extracellular reductase CorA reduces Cu2+ to Cu+, which is taken up by CopA when copper is limiting. 

We will discuss in more detail in Chapter 8 how intracellular copper levels are maintained at extremely low levels by a series of copper chaperone proteins, which sequester newly assimilated copper within the cytoplasm of cells and deliver it in a targeted manner to be incorporated into specific copper-containing proteins. While copper uptake across the gastrointestinal tract is poorly understood—most probably utilising the divalent cation transporter... 

We have already described the plasma membrane systems employed in yeast for copper uptake, and here we briefly describe the chaperone proteins involved in the intracellular transport and delivery of copper to target proteins (Figure 8.10), which were first described... 

Figure 18.4 Proteins involved in copper uptake, incorporation into ceruloplasmin and biliary excretion in normal and Wilson s disease hepatocytes. (From Crichton and Ward, 2006. Reproduced with permission from John Wiley Sons., Inc.)...

Treiber, C., Simons, A., Strauss, M., et al. (2004) Clioquinol mediates copper uptake and counteracts copper efflux activities of the amyloid precursor protein of Alzheimer s disease. J. Biol. Chem., 279, 51958-51964. 

Few studies have evaluated the potential for use of microorganisms in the remediation of sea water however, the problems encountered are similar to those of other aquatic systems. Stupakova et al. (1988) proposed the use of the marine bacteria Deleya venustus and Moraxella sp. for copper uptake from sea water. Additionally, Corpe (1975) performed metal-binding studies with copper using exopolymer from film-producing marine bacteria and found that insoluble copper precipitates formed, effectively decreasing copper toxicity. 

The high-affinity uptake system is more puzzling. It requires a permease encoded by FTRI and an additional protein encoded by FET3.30/33 35 The Fet3 protein is a copper oxidoreductase related to ceruloplasmin (Section D). The protein Frelp (encoded by FRE1) is a metalloreductase that reduces Cu2+ to Cu+, as well as Fe3+ to Fe2+. It is essential for copper uptake (Section D).33 It has long been known that ceruloplasmin is required for mobilization of iron from mammalian tissues.30 Hereditary ceruloplasmin deficiency causes accumulation of iron in tissues.36 Yeast also contains both mitochondrial and vacuolar iron transporters.37/37a b... 

Copper Uptake by Ryegrass Grown in Calcareous Soil Amended with Sewage Sludge, Pig Manure, and Green Manure in Greenhouse Experiment... 

Implications for Human Nutrition. The human studies cited have examined the effect of zinc on copper uptake, and evidence suggests that Zn/Cu ratios of greater than 10 1 can produce a nutritional impact. The source of the discrepancies among the three metabolic studies reviewed is not immediately evident. One possibility would be a different susceptibility to copper malabsorption at different ages. Another might have to do with the actual Zn/Cu ratios in those meals which provided the bulk of the daily Intake of the two minerals or with their chemical forms. Studies in which all of the copper and zinc are derived from natural foodstuffs would complement the foregoing human studies in this area. 

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