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PubMed2004

Synthesis, spectra and biomimetic properties of copper(II)-copper(II) and copper(II)-zinc(II) binuclear complexes with CuN5 chromophores.

X-band electron spin resonance (ESR) and UV-vis spectra of a homobinuclear [(Bipy)2Cu-E-Im-Cu(Bipy)2](BF4)3 and a heterobinuclear [(Bipy)2Cu-E-Im-Zn(Bipy)2](BF4)3 complexes, E-Im=2-ethylimidazolate ion have been described as possible models for superoxide dismutase (SOD). Magnetic moment and ESR spectral measurements of the homobinuclear complex have shown an antiferromagnetic exchange interaction. From pH-dependent ESR and UV-vis spectral measurements studies, these complexes have been found to be stable over 8.5-10.5 pH range. These complexes catalyze the dismutation of superoxide (O2-) at biological pH. All the observations indicate that these complexes act as good possible models for superoxide dismutase.

Anti-Bacterial Agents↗
PubMed1984

X-ray absorption study of Rhus laccase: evidence for a copper-copper interaction, which disappears on type 2 copper removal.

X-ray absorption spectra are reported for the multi-Cu oxidase Rhus vernicifera laccase in oxidized and fully reduced forms and for laccase from which the type 2 Cu has been depleted (T2D). The structure of the Cu K edge for both preparations shows the presence of CuII and CuI in the oxidized and reduced states, respectively. As previously reported by LuBien et al. (1981), removal of the type 2 Cu leads to reduction of the type 3 center, which can be reoxidized with H2O2. Fourier transforms of the extended X-ray absorption fine structure (EXAFS) give well-defined first and outer shell scattering peaks. Analysis of the first shell peak is complicated by the heterogeneity of the Cu sites. When (imidazole)4CuIISO4 is used as a model of the average Cu-ligand interactions, it is shown that all of the first shell peaks contain 2.7-3.5 near neighbors per Cu, at an average distance of 1.97-1.98 A. For T2D laccase, the fit is improved by inclusion of one-third of a sulfur atom at 2.19 A, corresponding to the presumptive cysteine ligand of the type 1 Cu, which remains in the preparation containing three Cu atoms per molecule. The outer shell region shows two peaks characteristic of scattering from distant imidazole atoms. For T2D laccase the filtered outer shell contribution can be satisfactorily fit by scattering from an average of 2.1-2.4 imidazole groups. For native laccase, however, imidazole alone cannot satisfactorily model the outer shell contribution.(ABSTRACT TRUNCATED AT 250 WORDS)

Copper↗
PubMed1977

The binding of copper ions to copper-free bovine superoxide dismutase. Properties of the protein recombined with increasing amounts of copper ions.

1. E.p.r. (electron-paramagnetic-resonance), proton-relaxation and u.v.-absorption parameters, and enzyme activity of samples of Cu2+-free bovine superoxide dismutase recombined with different amounts of Cu2+ up to the stoicheiometric [Cu2+]/protein] ratio were investigated after attainment of equilibrium in the recovery process. 2. The e.p.r. spectra were identical with the spectrum of the native protein at all [Cu2+]/[protein] ratios. The relaxation rate of the water protons (T1) and the u.v. absorption increase as linear functions of the added Cu2+. 3. On the other hand, in recombination experiments in the range pH 7.6-10.5 the enzyme activity shows a non-linear increase as the [Cu2+]/[protein] ratio rises. The experimental curves can be interpreted in terms of the model of co-operative binding of Cu2+ to the two sites proposed on the basis of the electrophoretic analyses of the samples, and show that the specific activity of the molecules containing only one Cu2+ ion is twice as high as that of the molecules with two Cu2+ ions. 4. These results support the hypothesis of an anti-co-operative interaction between the two sites during the activity, which allows only one Cu2+ ion to function in catalysis.

Animals↗
PubMed1998

Copper metabolism in the kidney of rats administered copper and copper-metallothionein.

To gain a greater understanding of the mechanism of Cu metabolism in kidneys of rats, using autofluorescence of Cu-metallothioneins (Cu-MTs) we revealed the behavior of Cu-MT in the kidneys of rats administered Cu-MT. Yellow and orange fluorescent signals of Cu-MT were observed in the cortex. By microscopic studies, Cu-MT was dominant in the proximal convolute tubular cells of the cortex. A high concentration of Cu-MT presented in the lysosome-like organelles of the proximal convolute tubular adjacent to the glomeruli. During the time course after the injection, the orange signal in lysosome-like organelles gradually converted to a yellow signal, indicating that the Cu-MT was involved in a degradation process in lysosomes by oxidation, and the MT mRNA increased in the cortex, although the immunoreactivity of MT was almost constant in the same region. These results suggested that Cu bound to the injected MT was released in lysosomes and became a new inducer of MT biosynthesis in the cortex. In conclusion, the biosynthesis and degradation of Cu-MT occur repeatedly in the proximal convolute tubular cells.

Animals↗
PubMed2003

Copper, zinc-superoxide dismutase protein but not mRNA is lower in copper-deficient mice and mice lacking the copper chaperone for superoxide dismutase.

Cu, Zn-superoxide dismutase (SOD1) is an abundant metalloenzyme important in scavenging superoxide ions. Cu-deficient rats have lower SOD1 activity and protein, possibly because apo-SOD1 is degraded faster than holo-SOD1. Previous work with mice lacking the Cu chaperone for SOD1 (CCS) indicated a drastic loss of SOD1 activity but not protein, suggesting an accumulation of apo-SOD1. We produced dietary Cu deficiency in mice to clarify this issue. Compared with Cu-deficient rats, reduction in liver SOD1 activity and protein was much less than Cu-deficient mouse dams and offspring. However, after perinatal Cu deficiency, 4-week-old mouse pups had lower levels of SOD1 activity and protein in liver and heart, but not brain, compared with Cu-adequate controls. Reduction in brain Cu was greater than liver. In CCS -/- mice, there was severe reduction in liver, heart, and brain SOD1 activity and protein. In fact, the reduction in activity was similar to the loss of protein. Neither Cu-deficient mouse liver nor CCS -/- mouse liver had altered SOD1 mRNA levels compared with control values. These results in mice are comparable with rats and suggest a posttranscriptional mechanism for reduction of SOD1 protein when Cu is limiting in SOD1.

Animals↗
PubMed1993

Comparison of copper lysine and copper sulfate as copper sources for ruminants using in vitro methods.

Two in vitro experiments were conducted to estimate the availability of Cu from Cu Lys compared with Cu from CuSO4. In experiment 1, a 24-h ruminal fermentation (alpha-cellulose substrate) containing either .1% added S or 2% added urea was performed with 4, 12, or 96 ppm of added Cu as either Cu Lys or CuSO4. Soluble Cu was measured at the end of the 24-h incubation, and concentrations were higher for Cu Lys with added urea (1.16 vs. .45 ppm), but no differences existed between sources of added S. In Experiment 2, 20 ppm of Cu added as either Cu Lys or CuSO4 with and without the addition of 10 ppm of Mo and .75% S were used in an vitro study designed to simulate digesta passage through the ruminant. A 24-h ruminal fermentation (orchardgrass substrate) was followed by a 2-h digestion in pepsin and HCl (pH 2.3) and then a 2-h digestion in NaHCO3 and pancreatin (pH 6.6). Soluble Cu concentrations were analyzed after each step. Molybdenum and S addition decreased soluble Cu after ruminal fermentation and tended to decrease soluble Cu concentrations after digestion of pancreatin and NaHCO3. The source of Cu did not affect soluble Cu concentrations. Results suggest that Cu from Cu Lys and CuSO4 behave similarly in the digestive tract of ruminants.

Animals↗
PubMed1993

Bioavailability of copper in analytical-grade and feed-grade inorganic copper sources when fed to provide copper at levels below the chick's requirement.

Young chicks were fed a casein-soy protein concentrate basal diet (.56 mg Cu/kg) containing graded levels of added Cu (0, .5, 1.0 mg/kg) from analytical-grade (AG) CuSO4.5H2O, Cu2O, CuO, CuCO3.Cu(OH)2, CuCl, and also from feed-grade (FG) CuSO4.5H2O and FG-CuO. Weight gain, hematocrit, hemoglobin, plasma Cu, liver Cu, gall bladder (bile) Cu, and tendon lysine were assessed to determine whether dose-dependent Cu responses would occur. Gall bladder Cu concentration as well as total Cu content of the gall bladder were found to be linear functions of supplemental Cu intake. Common-intercept multiple linear regression (slope-ratio) of bile Cu concentration regressed on supplemental Cu intake indicated Cu bioavailability values (relative to the standard, AG-CuSO4.5H2O, set at 100%) of 97.9% for AG-Cu2O, 93.5% for FG-CuSO4.5H2O, and 112.9% for AG-CuCO3.Cu(OH)2. These values were not different (P > .05) from 100%. Relative bioavailability of Cu in AG-CuCl was 142.5%, which was different (P < .05) from the standard. Both AG-CuO and FG-CuO gave Cu bioavailability estimates not different (P > .05) from zero. The results indicate that when Cu levels are fed below the chick's requirement, bile Cu concentration is a sensitive indicator of net gut absorption of Cu.

Animal Feed↗
PubMed1994

Interactive effects of dietary copper and water copper level on growth, water intake, and plasma and liver copper concentrations of poults.

The interactive effects of dietary Cu and water Cu on poult growth, water intake, whole-blood hemoglobin (Hb), and plasma and liver Cu concentrations were investigated using 232-9-old toms. Poults were randomly assigned to two levels of dietary Cu [Basal (B) and B + 204 mg Cu/kg diet] and to four levels of water Cu (0, 51.5, 103, and 206 mg Cu/kg water) in a 2 x 4 factorial arrangement of treatments. Each treatment was replicated six times. All poults received tap water during Days 1 to 5 followed by the water Cu treatments during Days 6 to 10. Water intake was measured daily and gain and feed intake were determined on Days 5 and 10. Day 1 to 5 gain was reduced (P < .02) in poults fed supplemental dietary Cu. Day 1 to 5 feed intake and gain:feed and Day 6 to 10 gain, feed intake, gain:feed, and water intake were not affected (P > .10) by dietary Cu.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Interactive effects of dietary copper, water copper, and Eimeria spp. infection on growth, water intake, and plasma and liver copper concentrations of poults.

The effects of dietary Cu, water Cu, and coccidial infection on poult growth performance and selected tissue mineral concentrations were investigated in a 10-d experiment using 200 5-d-old Nicholas toms (five replicates of 5 poults each; initial weight = 85 g). Uninfected and coccidiosis-infected (Eimeria meleagrimitis, Eimeria dispersa, Eimeria adenoeides, and Eimeria gallopavonis; cocci) poults were assigned to two levels of dietary Cu [Basal (B) and B + 204 mg Cu/kg diet on Days 1 to 10] and two levels of water Cu (0 and 103 mg Cu/kg water on Days 6 to 10). Dietary Cu and water Cu (main effects) did not affect (P > .10) gain, feed intake, gain:feed, water intake, hemoglobin, hematocrit, or liver Fe and Zn concentrations. Dietary Cu and water Cu increased (P < .03) liver and plasma Cu concentrations. The combination of dietary Cu and water Cu increased plasma Cu more than the sum of the Cu additions (dietary Cu by water Cu, P < .08). Coccidial infection reduced (P < .07) gain, feed intake, gain:feed, water intake, and hemoglobin, and increased (P < .02) liver Zn. Water Cu reduced water intake in uninfected poults but increased water intake in coccidiosis-infected poults (water Cu by cocci, P < .07). Water Cu increased hemoglobin in uninfected poults but decreased hemoglobin in coccidiosis-infected poults (water Cu by cocci, P < .07). Water Cu increased plasma Cu and liver Cu more in coccidiosis-infected poults than in uninfected poults (water Cu by cocci, P < .02).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗