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PubMed1984

Studies of copper(II) binding to glycylglycyl-L-tyrosine-N-methyl amide, a peptide mimicking the NH2-terminal copper(II)-binding site of dog serum albumin by analytical potentiometry, spectrophotometry, CD, and NMR spectroscopy.

Unlike human serum albumin (HSA), dog serum albumin (DSA) does not possess the characteristics of the specific first binding site for Cu(II). In DSA, the important histidine residue in the third position, responsible for the Cu(II)-binding specificity in HSA, is replaced by a tyrosine residue. In order to study the influence of the tyrosine residue in the third position of DSA, a simple model of the NH2-terminal native sequence tripeptide of DSA, glycylglycyl-L-tyrosine-N-methylamide (GGTNMA) was synthesized and its Cu(II)-binding properties studied by analytical potentiometry, spectrophotometry, CD, and NMR spectroscopy. The species analysis indicated the existence of five mono-complexes at different protonation states: MHA, MA, MH-1A, MH-2A, MH-3A, and only one bis-complex MH-2A-2. The complexing ability of GGTNMA to Cu(II) was found to be weaker than that of the Cu(II) binding peptide models of HSA. The visible absorption spectra of Cu(II)-GGTNMA complexes are similar to those observed in the case of DSA-Cu(II) complexes. The weaker binding and the spectral properties of Cu(II)-GGTNMA complexes are consistent with less specific Cu(II)-binding properties of the peptide of this sequence similar to what was noted with DSA. CD results are in excellent agreement with species analysis and visible spectra where it is clearly evident that Cu(II) binds to GGTNMA starting from the alpha-NH2 group and step by step to deprotonated amide nitrogens as the pH is raised. The absence of any charge transfer band around 400 nm strongly indicates that Cu(II) does not bind to the phenolate group. Furthermore, NMR results are consistent with the noninvolvement of the tyrosine residue of GGTNMA in Cu(II) complexation. Thus, it is clear that the low Cu(II)-binding affinity of DSA is due to the genetic substitution of tyrosine for histidine at the NH2-terminal region of the protein.

Animals↗
PubMed1984

A cupric ion-copper bioaccumulation relationship in coho salmon exposed to copper-containing treated sewage.

Exposure of coho salmon for 25 days to dilutions of sewage treatment plant effluent with river water containing added Cu (either 35 or 70 micrograms total Cu 1(-1) and an array of Cu2+ concentrations resulted in accumulations of Cu in gill and liver tissues that (a) correlated positively with the Cu2+ contents of the solutions; (b) reached a plateau coincident with onset of mortalities; and (c) correlated positively between these two tissues. Increases in hematocrit percentage and plasma albumin levels occurred in response to 7 micrograms Cu2+ 1(-1), indicating hemoconcentration. Treatment of blood in vitro under similar conditions resulted in association of Cu with the plasma rather than with the erythrocyte fraction.

Animals↗
PubMed1992

Seasonal changes in subcellular distribution of zinc, copper, cadmium and metallothionein in the liver of bank vole (Clethrionomys glareolus): a possible essential role of cadmium and metallothionein in the hepatic metabolism of copper.

1. An increase in total Zn concentration in the liver of sexually mature bank voles in spring and summer was primarily accompanied by an increase in Zn levels in the nuclear and mitochondrial-lysosomal fractions, while in immature voles in an analogous situation, Zn tended to concentrate mainly in the post-mitochondrial fraction. 2. Seasonal changes in Cu concentration in all subcellular fractions followed closely those of total hepatic Cu; however, the mitochondrial-lysosomal Cu underwent the most dramatic changes. 3. Multiple regression analysis between the concentration of metallothionein (MT) in the postmitochondrial fraction and the levels of Zn, Cu and Cd in the particular subcellular fractions showed that MT was principally induced by small amounts of Cd concentration of which in the liver ranged from 0.019 microgram/g in winter to 1.1 micrograms/g wet wt in spring. 4. The analysis revealed further that the level of MT in the post-mitochondrial fraction concurrently decreased as total hepatic Cu, as well as mitochondrial-lysosomal Cu, increased. 5. The data indicate that MT, first induced by small amounts of Cd, is involved in the hepatic metabolism of Cu in bank voles; most probably the protein sequesters free Cu ions in cytoplasm and then transfer them into the mitochondrial-lysosomal fraction.

Animals↗
PubMed2005

Do copper tolerant fathead minnows produce copper tolerant adult offspring?

The objective of this study was to determine if the relative Cu tolerance of fathead minnow parents determines the relative Cu tolerance of their adult offspring. It was hypothesized that the adult offspring of Cu-tolerant minnows would inherit Cu tolerance from their parents. The relative Cu tolerance of 96 adult fish was determined based upon their reduction in swim performance following a sublethal exposure to 150 microg Cu/l. Control, Cu-tolerant and Cu-susceptible lines of fish were produced and fish within each line were allowed to breed. The offspring were raised to adults, then exposed to one of two sublethal Cu concentrations (150 or 225 microg Cu/l) for 8 days. There were no significant differences in relative Cu tolerance, as measured by reduction in swim performance, among the three lines of fish at either dose. However, significant differences in whole body Na+ occurred among the fish lines after exposure to 150 microg Cu/l, but not after exposure to 225 microg Cu/l. Significant differences in whole body Cu occurred between Cu-tolerant and Cu-susceptible fish lines after exposure to either Cu dose. The offspring did not inherit the relative Cu tolerance of their parents, however, the selection lines had diverged from each other, particularly with respect to their whole body Cu concentrations after exposure.

Analysis of Variance↗
PubMed2006

Copper toxicity across salinities from freshwater to seawater in the euryhaline fish Fundulus heteroclitus: is copper an ionoregulatory toxicant in high salinities?

Two waterborne Cu exposures were performed to investigate if Cu is an ionoregulatory toxicant at all salinities in the killifish, Fundulus heteroclitus. A 30-day flow through exposure in 0 (FW), 5, 11, 22, and 28 ppt (SW) and three [Cu]'s (nominal 0, 30, and 150 microg Cu L(-1)) revealed no apparent Cu induced mortality at the intermediate salinities and high mortality in FW and SW. Fish were sampled at 4, 12, and 30 days after the start of the exposure and both Na+/K+ adenosine triphosphatase (Na+/K+ ATPase) and carbonic anhydrase (CA) activity in the gill and intestine as well as whole body [Na+], and [Cl-] were measured. At the high [Cu] a reduction of whole body [Na+] after 4 days of exposure in FW was the only physiological parameter influenced. A second static 24h Cu exposure was performed in FW, 5, 13, and 29 ppt (SW) and two [Cu]'s (nominal 0 and 110 microg Cu L(-1)). In addition to the parameters listed above, ammonia flux was measured at all salinities and Na+ flux was measured in FW fish. Cu affected ionoregulation in FW where decreased Na+ uptake associated with inhibition of Na+/K+ ATPase led to decreased whole body [Na+] after 24h. The only affected parameter in SW was net ammonia excretion suggesting that Cu is not an ionoregulatory toxicant in SW at the concentrations employed. We propose that physiology rather than chemistry explain much of the variation in Cu toxicity seen across salinities.

Adenosine Triphosphatases↗
PubMed2006

Accumulation of copper in brown rice and effect of copper on rice growth and grain yield in different rice cultivars.

A pot experiment with 38 commonly cultured rice cultivars showed that the effect of Cu (100 mg kg(-1)) on rice growth, grain yield and accumulation of Cu in brown rice varied greatly with different cultivars. Although the average Cu concentration in brown rice of the 38 cultivars was significantly increased (P<0.01) compared with the control, in none of the cultivars did Cu concentration in brown rice exceed the maximum permissible limit of 10 mg Cu kg(-1). This suggests that rice grown in Cu-contaminated paddy soil (100 mg Cu kg(-1)) will not adversely affect human health through the food chain. Because of the significant negative correlation between grain weight and Cu concentration in brown rice with the soil Cu treatment, screening for cultivars with low Cu accumulation in brown rice and high grain yield for Cu-contaminated areas is feasible. The present research led to the recommendation of three such cultivars: Jiahua, Zhenxian 866, Zhe 733. The average grain yield under Cu treatment (100 mg Cu kg(-1) soil) was significantly (P<0.01) reduced compared with the control. The decreases or increases of grain yields mainly resulted from the combined effects of the panicles per pot, spikelets per panicle and filled spikelets per panicle under the soil Cu treatment. Furthermore, there were significant (r=0.869, P<0.01) positive correlations between the RC (relative changes) of spikelets per panicle and filled spikelets per panicle under the soil Cu treatment.

Copper↗
PubMed2004

Copper uptake by Elsholtzia splendens and Silene vulgaris and assessment of copper phytoavailability in contaminated soils.

Tolerance and metal uptake are two essential characteristics required for phytoextraction of metals from contaminated soils. We compared tolerance and Cu uptake of Elsholtzia splendens (reported previously to be a Cu hyperaccumulator) with Silene vulgaris (the Imsbach population, a well-known Cu-tolerant excluder species), using 30 soils varying widely in total Cu concentration (19-8645 mg kg(-1)). We further investigated the effectiveness of different soil testing methods for predicting plant metal uptake. The results showed that both Elsholtzia splendens and Silene vulgaris were tolerant to Cu, especially Silene vulgaris. However, Elsholtzia splendens did not hyperaccumulate Cu, but behaved as a typical Cu excluder like Silene vulgaris. The concentrations of Cu in both plants correlated more closely with 1 M NH4NO3 extractable Cu, soil solution Cu, or effective Cu concentration determined using DGT, than with soil total Cu, EDTA extractable Cu or free Cu2+ activity. The relationships between soil solution properties and root Cu concentrations were further investigated using multiple regression. The results showed that increasing soil solution pH increased root Cu concentration when free Cu2+ activity was held constant, suggesting a higher phytoavailability of free Cu2+ at a higher pH. Soil solution DOC appeared to play two contrasting roles on the phytoavailability of Cu: (1) reducing Cu availability by complexing Cu; and (2) increasing Cu availability at the same level of free Cu2+ activity by providing a strong buffer for free Cu2+. The results are consistent with the intensity/capacity concept for phytoavailability of metals in soils.

Copper↗
PubMed2005

Molecular-level investigation into copper complexes on vermiculite: effect of reduction of structural iron on copper complexation.

In this paper we present results that describe the speciation of Cu sorbed to the clay mineral vermiculite, with special attention to the effects of reduction on Cu sorption complexes. Sorption complexes were studied using powdered extended X-ray absorption fine structure (EXAFS) spectroscopy, polarized EXAFS spectroscopy, and X-ray diffraction (XRD). Ionic strength (I), background ion, and clay reduction (structural iron) were varied in the sorption samples. At low I EXAFS results indicate that Cu was surrounded by up to six water molecules sorbed in the interlayer of reduced vermiculite. EXAFS results from Cu-equilibrated reduced vermiculite with high I Ca background electrolyte revealed that Cu was surrounded by 4 O atoms at 1.95 Angatroms and 8 second shell O atoms at 3.14 Angstroms. Angular dependence of the second shell O atoms interpreted from the polarized-EXAFS spectra indicated that the atoms are out of plane from the basal plane of the vermiculite (inclined approximately 25 degrees from the ab plane). The local atomic environment and angular dependence of the EXAFS spectra suggest that the Cu atoms are adsorbed above the hexagonal cavities of the reduced clay mineral and form a Cu dimer in the interlayer. This adsorption mechanism was not observed in the non-reduced vermiculite under identical equilibration conditions. Our results provide molecular level evidence that Cu sorption mechanisms on vermiculite are dependent on solution conditions, such as redox potential and background electrolyte. These results can be used to develop better models of Cu sorption mechanisms on clay mineral surfaces.

Adsorption↗