Showing papers on "Zinc published in 1976"
TL;DR: The crystal structure analysis of horse liver alcohol dehydrogenase has been extended to 2.4 A resolution and the positions of the 374 amino acids in the polypeptide chain of each subunit are determined.
644 citations
TL;DR: The net uptake of copper by the mussel was extremely erratic, and was affected by salinity and temperature changes and by the presence of the other metals and changes in their relative concentrations, it is suggested that the mussels should not be used as an indicator of copper in the marine environment.
Abstract: The net uptake of zinc, cadmium, lead and copper by the common mussel Mytilus edulis (L.) exposed to different conditions was investigated with a view to using this species as an indicator of contamination of the marine environment by these metals. The variables studied were season, position of the mussel in the water column, water salinity, water temperature, and the simultaneous presence of all four metals. Each of these 5 variables affected the net uptake of some or all of the metals studied under some conditions. Seasonal variation in concentrations of zinc, cadmium and copper was found in samples collected at three separate locations. The relationship of seasonal variation to tissue weight and absorption route of the metals is discussed. Near to freshwater inputs of trace metals, the concentrations of zinc, cadmium and lead in mussels were found to vary according to the depth at which the mussels were collected; in summer when freshwater run-off is less, this effect was absent. Low salinities did not affect the net uptake of zinc by mussels, but increased the net uptake of cadmium and decreased that of lead. Low temperatures had no effect on the net uptake of zinc or lead; the net uptake of cadmium was unaffected by low temperatures at high salinities but was decreased by low temperatures at low salinities. The presence of the other metals had no effect on the individual net uptake of either zinc, cadmium or lead. A sampling programme was devised to eliminate the effects of these environmental variables and to allow the use of M. edulis as an indicator of zinc, cadmium and lead in marine and estuarine environments. In contrast to the other metals, the net uptake of copper by the mussel was extremely erratic, and was affected by salinity and temperature changes and by the presence of the other metals and changes in their relative concentrations. The effects of other metals on the net uptake of copper cannot be easily eliminated or allowed for; it is, therefore, suggested that the mussel should not be used as an indicator of copper in the marine environment.
502 citations
TL;DR: Mouse-derived metallothionein was found to consist of two distinct cadmium-binding proteins possessing similar absorption and metal-binding properties, and it is suggested that tolerance to Cd seen in pretreated mice is a result of the subsequent in vivo displacement of Zn from, and the chelation of Cd to, metallothsionein.
257 citations
TL;DR: The addition of zinc was associated with a lower incidence of disturbed gastrointestinal function and not accompanied by any signs of toxicity and, in this double-blind controlled study, the effects of supplementing Similac with iron with 4 mg/liter of zinc were determined.
249 citations
229 citations
TL;DR: The syndrome the authors have recognized in adult man has not been previously described and resembles however the parakeratosis of zinc deficient swine and it is also very similar to Acrodermatitis enteropathica, a genetically determined disorder of infants very recently linked to zinc deficiency.
Abstract: Changes in the plasma and urine levels of the trace metal zinc have been followed in a series of 37 adult patients totally supported by intravenous alimentation. Copper has also been determined in more recent cases. In such a seriously ill group, although urinary zinc loss may be very high at the height of catabolism, severe plasma depletion does not occur unless there is a subsequent phase of sustained anabolism and weight gain. In four patients plasma zinc fell to very low levels during this phase and three of this group developed a syndrome characterized by diarrhea, mental depression, para-nasal, oral and peri-oral dermatitis, and alopecia. The response to oral or intravenous zinc therapy is striking, except for hair regrowth which is delayed but eventually complete. The syndrome we have recognized in adult man has not been previously described. It resembles however the parakeratosis of zinc deficient swine and it is also very similar to Acrodermatitis enteropathica, a genetically determined disorder of infants very recently linked to zinc deficiency. Zinc is clearly essential to human metabolism and it should be included in all parenteral alimentation regimes particularly during the period of rapid, sustained, weight gain.
226 citations
TL;DR: In this paper, an ionic equilibria computer program was used to predict the effect of various complexing agents on trace metal species in sea-water, with the exception of l-cysteine.
218 citations
TL;DR: In this article, X-ray scattering measurements have been carried out for concentrated aqueous solutions of divalent transition-metal perchlorates of manganese(II) to zinc(II).
Abstract: X-ray scattering measurements have been carried out for concentrated aqueous solutions of divalent transition-metal perchlorates of manganese(II) to zinc(II). The radial distribution curves showed that each central metal ion was octahedrally surrounded by six water molecules at the distances of 2.20 A for Mn2+–OH2, 2.12 A for Fe2+–OH2, 2.08 A for Co2+–OH2, 2.04 A for Ni2+–OH2, and 2.08 A for Zn2+–OH2. The results from the radial distribution curves were confirmed by the direct analysis of reduced intensities. Concentrated aqueous solutions of copper(II) and zinc(II) sulfates have also been measured. The bond distances of 1.94 A for the Cu2+–OH2 (equatorial), 2.38 A for the Cu2+–OH2 (axial) and 2.08 A for Zn2+–OH2 were consistent with those obtained for the perchlorate solutions. No evidence for the contact ion pairs of metal and sulfate ions was found by the present X-ray measurements. The bond energies between metal ions including copper ion were discussed by application of the Garrick model with a sligh...
207 citations
TL;DR: Increased amounts of copper, iron, and zinc were found in multiparous women whether or not they had previously lactated, and milk from older women had lower iron and higher copper and zinc contents than that from younger women.
201 citations
Journal Article•
194 citations
TL;DR: In this paper, the composition of a film from a thiophosphate additive was explored using Argon ion etching and it was shown that there were no large compositional variations through the thickness of the film and that it was of a discontinuous patchy nature.
TL;DR: A number of minor and trace elements including Be, C, Ca, Cr, K, Li, Mn, Na, P, Pb, S, Tl, V and Zn present in coal fly ash are found to be preferentially concentrated on the particle surfaces.
Abstract: A number of minor and trace elements including Be, C, Ca, Cr, K, Li, Mn, Na, P, Pb, S, Tl, V, and Zn present in coal fly ash are found to be preferentially concentrated on the particle surfaces. Environmentally effective concentrations of these elements are thus much higher than indicated by conventional bulk analyses.
TL;DR: At 77 K the fluorescence and phosphorescence emission spectra of Sn and Zn cytochrome c show evidence of resolution into vibrational bands, which correspond with those obtained by resonance Raman spectroscopy for in-plane deformations of the porphyrin macrocycle.
Abstract: Tin (Sn4+) and zinc (Zn2+) derivatives of horse heart cytochrome c have been prepared and their optical spectra have been characterized. Zinc cytochrome c has visible absorption maxima at 549 and 585 nm and Soret absorption at 423 nm. Tin cytochrome c shows visible absorption maxima at 536 and 574 nm and Soret absorption at 410 nm. Unlike iron cytochrome c in which the emission spectrum of the porphyrin is almost completely quenched by the central metal, the zinc and tin derivatives of cytochrome c are both fluorescent and phosphorescent. The fluorescence maxima of zinc cytochrome c are at 590 and 640 nm and the fluorescence lifetime is 3.2 ns. The fluorescence maxima of Sn cytochrome are at 580 and 636 nm and the fluorescence lifetime is under 1 ns. The quantum yield of fluorescence is Zn greater than Sn while the quantum yield of phosphorescence is Sn greater than Zn. at 77 K the fluorescence and phosphorescence emission spectra of Sn and Zn cytochrome c show evidence of resolution into vibrational bands. The best resolved bands occur at frequency differences 750 cm-1 and 1540--1550 cm-1 from the O-O transition. These frequencies correspond with those obtained by resonance Raman spectroscopy for in-plane deformations of the porphyrin macrocycle.
TL;DR: The biochemistry of zinc has come under intensive investigation at the molecular level during the past 20 years, and substitution of zinc by cobalt serves to locate a paramagnetic probe at the active site of the enzyme which can then provide information regarding the coordination properties of the metal and theactive site environment.
TL;DR: The study of the distribution of Cd, ZN and Cu in homogenates of mussels has shown that Zn and Cu are principally associated with high mol.
Abstract: The study of the distribution of Cd, Zn and Cu in homogenates of mussels has shown that Zn and Cu are principally associated with high mol. wt. proteins. The same distribution is observed for Cd in untreated mussels, but in Cd chronically intoxicated animals, the metal is principally bound to low mol. wt. proteins synthesized in response to the uptake of the cation and similar to metallothioneins of vertebrates.
TL;DR: Accumulation of cadmium was associated with an increased zinc concentration in the liver and an increased copper concentration inThe kidney; these increases were correlated with increases in liver and kidney metallothioneins induced by cad mium.
TL;DR: The data indicate that the protective effect of zinc on lead toxicity is largely mediated by an inhibition of lead absorption at the intestinal level, and infected zinc did not afford protection against lead toxicity.
Abstract: An investigation of the influence of dietary zinc (8, 35, 200 ppm) on the toxicity of dietary lead (0, 50, 200 ppm) in the young male rat in a seven week period indicated that as dietary zinc increased, the severity of lead toxicity decreased. Evidence included decreased lead concentration in blood, liver, kidneys, and tibias; decreased excretion of urinary delta-aminolevulinic acid; decreased accumulation of free erythrocyte porphyrins; decreased inhibition of kidney delta-aminolevulinic acid dehydrase activity; and a decrease in apparent lead absorption. Infected zinc did not afford protection against lead toxicity. The data indicate that the protective effect of zinc on lead toxicity is largely mediated by an inhibition of lead absorption at the intestinal level.
TL;DR: In this article, the zinc level in the expressed prostate secretion (EPS) of 49 control men averaged 448 μg. per milliliter (range 0 to 139 μg) and 50 μg in 15 men with chronic bacterial prostatitis averaged 50 μg.
TL;DR: The mixed copper- and zinc-binding proteins induced in rat liver after injection of copper were isolated and characterized as metallothioneins, with 7-11% total metal in the protein, equivalent to 2.6-1.6 cysteine residues/metal atom.
Abstract: The mixed copper- and zinc-binding proteins, with mol.wt. of approx. 12000, induced in rat liver after injection of copper were isolated and characterized as metallothioneins. Three separate forms were obtained, with 7-11% total metal in the protein, equivalent to 2.6-1.6 cysteine residues/metal atom.
TL;DR: Cadmium and zinc toxicity to the flagfish was determined on the basis of 96-h median lethal concentrations (LC50) and significant decreases (P = 0.05) in survival, growth, and reproduction over the complete life cycle of the fish.
Abstract: Cadmium and zinc toxicity to the flagfish (Jordanella floridae) was determined on the basis of 96-h median lethal concentrations (LC50) and significant decreases (P = 0.05) in survival, growth, and reproduction over the complete life cycle of the fish. The 96-h LC50 values for cadmium and zinc to juvenile flagfish were 2500 and 1500 μg/liter, respectively. In chronic tests, reproduction was the most sensitive indicator of cadmium toxicity and was inhibited at 8.1 μg/liter. Tissue-concentration analysis showed that fish exposed to concentrations of 1.7 μg/liter and above accumulated significantly greater amounts of cadmium than those in the controls. In zinc tests, survival of larvae (not exposed as embryos) and growth of females were the most sensitive measure of zinc toxicity and were reduced at respective concentrations of 85 and 51 μg/liter. Significant uptake of zinc occurred in fish exposed to concentrations of 47 μg/liter and above. The lowest cadmium and zinc concentrations causing adverse effects ...
TL;DR: In this paper, the critical zinc level during early plant growth was 13 μg/g dry weight in recently matured leaves (blade three) in cotton (Gossypium hirsutum L.).
Abstract: Photosynthesis, respiration, carbonic anhydrase activity and chlorophyll concentrations were correlated with zinc nutrition in cotton (Gossypium hirsutum L.). The critical zinc level during early plant growth was 13 μg/g dry weight in recently matured leaves (blade three). Photosynthesis and chlorophyll concentration required a minimum Zn of 13 and 14 μg/g dry weight, respectively, in blade three for maximum activity and synthesis. Respiration was not influenced by zinc status. Carbonic anhydrase activity increased curvilinearly as zinc status improved from deficiency to adequacy.
TL;DR: The results suggest that zinc complexes with rhinovirus coat proteins and alters them so that they cannot function as substrates for proteases or as reactants in the assembly of the virus particles.
Abstract: Zinic ions rapidly inhibit virus production in HeLa cells infected with human rhinovirus type 1A and lead to the accumulation of human rhinovirus type 1A precursor polypeptides. The degree to which cleavage of these precursors is inhibited is directly dependent on the quantity of cell-associated zinc. Proteolysis resumes after the removal of zinc-containing medium, and the accumulated viral precursors are cleaved predominantly to stable virus polypeptides. The precursors stabilized at the lowest zinc levels are those that contain capsid protein sequences. Furthermore, added zinc is bound to human rhinovirus type 1A capsids and prevents them from forming crystals. Zinc-resistant mutants display antigenic alterations in coat proteins. These results suggest that zinc complexes with rhinovirus coat proteins and alters them so that they cannot function as substrates for proteases or as reactants in the assembly of the virus particles.
TL;DR: The present study was undertaken in an at tempt to further delineate the localization and nature of the metals in question and to show that application of chelating drugs, which abolish Timm stainability, has pronounced behavioural effects.
TL;DR: Assays of populations from Sites with high calcium levels suggest that these are less tolerant of a particular level of zinc than are populations from sites with low calcium levels, and that populations show increased resistance to zinc in comparison with populations from site with lower zinc levels.
Abstract: Field and laboratory studies have been carried out on the tolerance to zinc of Stigeoclonium tenue growing in flowing waters. Thirty-four different sites in England, France and Germany were included, the majority of them being chosen to represent examples of zinc pollution resulting from past or present mining activities. S. tenue was sometimes abundant in zinc polluted waters, and was found at sites with up to 20·0 mg l-1 of zinc capable of passing through a filter. At sites with field mean zinc levels of about 0·2 mg l-1 and above, populations show increased resistance to zinc in comparison with populations from sites with lower zinc levels, this increased resistance being largely, if not entirely, the result of genetic adaptation. Assays of populations from sites with high calcium levels suggest that these are less tolerant of a particular level of zinc than are populations from sites with low calcium levels. Levels of zinc bringing about a marked reduction in total growth during assay have a relativel...
TL;DR: The close similarity between the calculated and measured t 1/2 values for zinc-thionein suggests that release of Zn2+ from zinc- Thionein probably occurs simultaneously with degradation of the protein moiety.
Abstract: A low-molecular-weight protein, zinc-thionein, a metallothionein, was implicated as having a regulatory function in zinc metabolism. The half-life (t 1/2) of hepatic zinc-thionein was determined by pulse-labelling with either L-[35S] cystine and/or 65Zn. In two experiments with L-[35S]cystine, the t 1/2 of zinc-thionein was 18h and 19h. Most of the soluble 35S-labelled hepatic proteins had a t 1/2 of 4 days. The t 1/2 of zinc-thionein calculated by using 65Zn was 20h. The close similarity between the calculated and measured t 1/2 values for zinc-thionein suggests that release of Zn2+ from zinc-thionein probably occurs simultaneously with degradation of the protein moiety.
TL;DR: Poly-beta-hydroxybutyrate biosynthesis was shown to be initiated by a magnesium or sulfate deficiency as well as by a nitrogen or phosphate deficiency, and trace metal requirements for cobalt, chromium, and copper were demonstrated.
Abstract: Quantitative nutrient requirements for unrestricted autotrophic growth of Alcaligenes eutrophus were determined. Minimum saturating concentrations of Mg2+, SO42-, PO43-, Fe3+, and Na2+ for an optical density increase of 2 were 10(-4) M 8 X10(-5) M, 5 X 10(-4) to 6 X 10(-4) M, 10(-5) M, and 10(-7) to 2 X 10(-7) M, respectively. Trace metal requirements for cobalt, chromium, and copper were also demonstrated, but minimum concentrations could not be determined because other reagents contributed a high background of these metals. Under certain conditions an apparent response to zinc was observed, although other experiments suggest the zinc salt contained another metal that was required for growth. Poly-beta-hydroxybutyrate biosynthesis was shown to be initiated by a magnesium or sulfate deficiency as well as by a nitrogen or phosphate deficiency.