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Results for “Zinc Compounds”

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PubMed2001

[The effect of physiological and extreme irritants on zinc metabolism in pancreatic islets and hippocampus cells].

Zinc content in pancreatic islet cells and hippocampus was studied with the aid of highly sensitive selective cytochemical reaction of 8-(p-toluensulfonylamino)-quinoline. It was shown that the factors stimulating B-insulocyte secretory activity induced the decrease of this metal concentrations in the cell. An increase of these cells zinc content observed in the cases of their secretory activity inhibition. The extreme irritants induced two phase changes of zinc concentrations in pancreatic islets and hippocampus.

Aminoquinolines↗

PubMedDate not supplied

Distribution of histochemically reactive zinc in the forebrain of the rat.

The major cytoarchitectonic regions of the rat brain that stain with the Timm-Danscher metal stain were tested with the fluorescent probe for zinc, 6-methoxy 8-para toluene sulfonamide quinoline (TSQ). Throughout most of the striatum, cerebral cortex and limbic system, the diffuse, even neuropil staining produced by the Timm-Danscher method was mirrored by comparable fluorescence in TSQ-stained sections. Blockade of the TSQ fluorescence by prior treatment with sulphide indicated that the Timm-Danscher and the TSQ procedures both labeled the same pool of endogenous metal, which is inferred to be the zinc that is in axonal boutons. It is concluded that the Timm-Danscher staining generally indicates zinc-containing axonal boutons. The distribution of the zinc-containing axonal boutons throughout the forebrain is described.

Aminoquinolines↗

PubMed2005

How to hide zinc in a small protein.

Small cysteine-rich proteins (metallothioneins) and related domains of some large proteins (e.g., lysine methyltransferases) bind tri- and tetranuclear zinc clusters with topologies resembling fragments of Zn(II) sulfide minerals. These clusters are ubiquitous in animals, plants, and bacteria. Bacterial metallothioneins can also contain histidines as cluster ligands and embed Zn(II) with a "treble-clef"-like finger fold. This unusual embedded Zn(II) is "hidden" and surprisingly inert toward Zn or Cd exchange. Clearly, proteins can exert fine control over both the thermodynamics and kinetics of zinc binding in thiolate clusters. Genome sequences suggest that related zinc-finger sites are common in a variety of bacteria.

Amino Acid Sequence↗

PubMed2006

Influence of different transition metals in phthalocyanines on their interaction energies with volatile organic compounds: an experimental and computational study.

Experimental partition coefficients were determined for a series of volatile organic compounds (VOCs) (acetonitrile, n-butylamine, n-octane tetrachloroethene, and toluene) for the interaction with 2,3,9,10,16,17,23,24-octakis(octyloxy)-phthalocyaninato complexes, PcM(OR)(8), with varying central metal atoms [M=H(2) (metal-free), Ni, Pd, Cu, Zn]. Large partition coefficients for toluene were observed in the case of the nickel and palladium phthalocyanines, whereas for the corresponding zinc-containing compound, interaction with n-butylamine resulted in a high value for the partition coefficient. Interaction energies for model coordination complexes were obtained at the ab initio LMP2/ LACVP* level of theory. The interaction of various small volatiles with the various PcM(OR)(8) compounds was studied using the PM3 semiempirical Hamiltonian. Large values for interaction energies correspond to particularly strong partition coefficients, suggesting that coordination of the volatiles to the central metal dominates over the often discussed pi-system stacking at the PcM(OR)(8)'s.

Acetonitriles↗

PubMed2005

Detection and quantification of on-chip phosphorylated peptides by surface plasmon resonance imaging techniques using a phosphate capture molecule.

We describe herein a detection and quantification system for on-chip phosphorylation of peptides by surface plasmon resonance (SPR) imaging techniques using a newly synthesized phosphate capture molecule (i.e., biotinylated zinc(II) complex). The biotinylated compound is a dinuclear zinc(II) complex that is suitable for accessing phosphate anions as a bridging ligand on the two zinc(II) ions. The compound was exposed on the peptide array and detected with streptavidin (SA) via a biotin-SA interaction by SPR imaging. In the conventional method using antibody, both anti-phosphoserine and anti-phosphotyrosine antibodies were required for phosphoserine and phosphotyrosine detection, respectively. Detection of the phosphate group by the zinc(II) complex, however, was independent of the phosphorylated amino acid residues. The calibration curve for the phosphorylation ratios was established with a calibration chip, on which phosphoserine-containing peptide probes were immobilized. The peptide probes, which were phosphorylated on the surface by protein kinase A, were detected and quantified by SPR imaging using the zinc(II) complex, SA, and anti-SA antibody. The reaction rate and the kinetics of on-chip phosphorylation were also evaluated with the peptide array. The phosphorylation ratio was saturated at approximately 20% in 2 h in this study.

Microchip Analytical Procedures↗

PubMed2007

Effect of ionic crosslinking on the drug release properties of chitosan diacetate matrices.

Chitosan diacetate (CDA) was prepared by alkylating the amino moieties of chitosan with mono-iodoacetic acid. Subsequently, CDA was cross-linked with Al3+, Zn2+, and Ca2+ ions to yield three ionotropically crosslinked polymeric matrices. These composite matrices were characterized employing infrared spectroscopy (IR) and differential scanning calorimetry (DSC). Subsequently, they were loaded with caffeine, as a model drug, and were assessed as sustained release carriers by evaluating their caffeine release profiles. Interestingly, only CDA-Zn2+ complex sustained the release of caffeine effectively in a zero-order manner. The drug release and thermal behavior of the tested matrices agree with the relative strength of the ionic or coordination character of the bonds. This, in turn, depends on the position of the complexing ions on the electrophilic softness/hardness scale.

Alkylation↗

PubMed2006

Tissue distribution and subcellular localization of trace metals in the pond snail Lymnaea stagnalis with special reference to the role of lysosomal granules in metal sequestration.

The present study was undertaken to elucidate the cellular mechanisms, which govern metal sequestration and detoxification in gastropods. For this purpose the pond snail, Lymnaea stagnalis was exposed to environmentally relevant concentrations of three species of metals (Al, Zn and Cd) for 30 days and the localization and fate of these metals were followed in different tissues of the snails. The measurement of relative distribution of metals between tissues revealed that the digestive gland and kidney account for most of the accumulated metals. Al and Cd (non-essential metals) were redistributed to the digestive gland, possibly because of the presence of specific binding entities in the digestive glands of the herein species. This study focuses on the role of intracellular metal-containing granules on metal sequestration. Three main types of granules were identified in the digestive gland cells namely small, green and yellow granules. The morphological examination and the progressive accumulation of elements within these granules revealed that they are developmental stages with the yellow granule being the mature one. The total number of these granules was found to be significantly increased upon exposure of the snails to Al only. This increase may be a response to the large amount of Al that is accumulated through feeding route of this grazing snail. X-ray microanalysis (XRMA) revealed that metals were localized in all three types of digestive gland granules. The increased amount of ligands (P and S) in the granules may give evidence for their role in metal sequestration. Levels of Al and P were positively correlated in the digestive gland granules. It is possible that aluminium is bound to phosphorus to render it insoluble and so to both immobilize it within the lysosome and to be excreted in a highly insoluble form. On the other hand, both Zn and Cd induced marked upregulation of S in mature (yellow) granules by 26- and 11-folds, respectively. The lysosomal codeposition of S and either Cd or Zn in the lysosomal granules in addition to the increase in RER cisternae may indicate that the exposure to these metals could induce metallothionein synthesis in the cells. The microscopical examinations in the present study revealed that metal detoxification from the digestive gland cells may occur via faeces or via basal exocytosis towards hemocytes dispersed by the connective tissue in the visceral mass. In the kidney, one type of granules, the excretory concretions, was identified in the nephrocytes. The significant increase in the number of these concretions in the snail L. stagnalis upon exposure to metals may give further evidence for their role in metal excretion.

Aluminum Compounds↗

PubMed1993

Model for the interaction of crotoxin, a phospholipase A2 neurotoxin, with presynaptic membranes.

Crotoxin is a phospholipase A2 neurotoxin that impairs the release of acetylcholine at neuromuscular junctions, primarily at the presynaptic level. It associates a phospholipase A2 subunit, CB, with a chaperon subunit, CA. We have shown elsewhere that the purely cholinergic synaptosomes from the Torpedo electric organ provided a convenient model to study the pharmacology of crotoxin and other related neurotoxins [Délot, E., & Bon, C. (1992) J. Neurochem. 58, 311-319]. In the present experiments, we labeled crotoxin with 125I and demonstrated saturable binding to Torpedo presynaptic membranes. In the range of concentrations that was effective on synaptosomes, crotoxin bound to a single class of sites without cooperativity. The binding was affected by divalent cations, and its kinetics was rather complex. We observed a competition between crotoxin and related neurotoxins, but not CB. Although CA could not bind, it could compete efficiently with crotoxin. We compare our results with those previously obtained by others on guinea pig brain membranes. On Torpedo membranes, as on all models tested, CB was the major species bound to the membrane, while CA remained in solution. However, the mechanism underlying this phenomenon had never been clarified. The major question is the time scale of the events, i.e., does CB bind before or after dissociating from CA? Our results indicate that the predominant pathway involves the formation of a ternary complex between crotoxin's subunits and the acceptor site preceding the release of CA.

Acetylcholine↗

PubMed2005

Opposite effects of Zn on the in vitro binding of [3H]LY354740 to recombinant and native metabotropic glutamate 2 and 3 receptors.

We investigated the effect of Zn on agonist binding to both recombinant and native mGlu2 and mGlu3 receptors. Zn had a biphasic inhibitory effect on recombinant mGlu2 with IC(50) values for the high- and low-affinity components of 60 +/- 10 microM and 2 +/- 0.7 mM, respectively. Zn induced a complex biphasic effect of inhibition and enhancement of [(3)H]LY354740 binding to mGlu3. Observations with a series of chimeric mGlu2/3 receptors suggest that the Zn effect resides in the N-terminal domain of mGlu2 and mGlu3. We observed that the His56 of mGlu2, which corresponds to Asp63 in mGlu3 was largely accountable for the second phase of the Zn effect. As revealed by quantitative receptor radioautography, the addition of up to 100 microm Zn to brain sections of wild-type mice resulted in significant decreases in binding density in most brain regions. In particular, the mid-molecular layer of the dentate gyrus (DGmol) and the CA1 lacunosum moleculare of hippocampus (CA1-LMol) showed reductions of 62 and 67%, respectively. In contrast, the addition of 300 microM Zn to brain sections of mGlu2(-/-) mice caused large increases in binding density of 289 and 242% in DGmol and CA1-LMol, respectively. Therefore, Zn might play a role as a physiological modulator of group II mGlu receptor function.

Amino Acid Sequence↗

PubMed2001

Measurement of fecal sulfide using gas chromatography and a sulfur chemiluminescence detector.

We describe a simple technique to measure sulfide in fecal homogenates (or any other liquid milieu), which involves acidification followed by the G.C. measurement of H2S in a gas space equilibrated with a small quantity of homogenate. An internal standard of Zn35S added to the homogenate permits correction for incomplete recovery of H2S in the gas space. The use of a sulfur chemiluminescence detector, which specifically and sensitively responds to sulfur-containing compounds, greatly facilitates this measurement.

Chromatography, Gas↗

PubMed1983

Studies on the bioavailability of zinc in humans: intestinal interaction of tin and zinc.

Mineral/mineral interactions at the intestinal level are important in animal nutrition and toxicology, but only limited understanding of their extent or importance in humans has been developed. An inhibitory interaction of dietary tin on zinc retention has been recently described from human metabolic studies. We have explored the tin/zinc interaction using the change-in-plasma-zinc-concentration method with a standard dosage of 12.5 mg of zinc as zinc sulfate in 100 ml of Coca-Cola. Sn/Zn ratios of 2:1, 4:1, and 8:1, constituted by addition of 25, 50, and 100 mg of tin as stannous chloride, had no significant overall effect on zinc uptake. The 100-mg dose of tin produced noxious gastrointestinal symptoms. Addition of iron as ferrous sulfate to form ratios of Sn/Fe/Zn of 1:1:1 and 2:2:1 with the standard zinc solution and the appropriate doses of tin produced a reduction of zinc absorption not dissimilar from that seen previously with zinc and iron alone, and addition of picolinic acid did not influence the uptake of zinc from the solution with the 2:2:1 Sn/Fe/Zn ratio.

Adult↗

PubMedDate not supplied

[Contact allergy to olive oil].

Sensitization to olive oils has not yet been reported in the German literature. A 43 year old female developed increasing eczematous reactions after treatment of her leg with a boric acid/zinc oxide preparation in an oil vehicle. When different components of this zinc oxide/oil compound were tested, olive oil proved positive. A patch testing with other vegetable oils gave negative results.

Adult↗

PubMed1998

Identification of four amino acid residues essential for catalysis in human cytidine deaminase by site-directed mutagenesis and chemical modifications.

By site-directed mutagenesis on human cytidine deaminase (CDA), five mutant proteins were obtained: C65A, C99A, C102A, E67D and E67Q. The three cysteine mutants were completely inactive, whereas E67D and E67Q showed a specific activity about 200- and 200000-fold lower, respectively, than the wild-type CDA. Zinc analysis revealed that only E67D, E67Q and C65A contained 1 mol Zn2+/mol subunit as in the wild-type CDA. Kinetic measurements with the specific carboxylic group reagent N-ethoxy-carbonyl-2-ethoxy-1,2-dihydroquinoline performed on wild-type CDA suggest that Glu67 is essential for the catalytic process. Furthermore, when both native and denatured CDA was titrated with 5,5'-dithiobis(2-nitrobenzoic acid) six sulfhydryl groups were detected, whereas in the denatured and reduced enzyme nine such groups were found, according to the sequence data. When p-hydroxymercuriphenyl sulfonate was used, nine sulfhydryl groups were detectable and the release of 1 mol of zinc per mole of CDA subunit was revealed by the metal indicator dye 4-(2-pyridylazo)resorcinol. It seems plausible that the limiting step for the maintenance of zinc in the active site is the formation of coordination between Cys99 and Cys102, whereas Cys65 could lead the zinc to the correct position and orientation within the active site.

Amino Acid Substitution↗

PubMed1998

Inhibitory effect of zinc and copper on phosphatase activity in the brain cytosol of rats: involvement of SH groups.

The effect of various metal ions on neutral phosphatase activity in the brain cytosol of rats was investigated. p-Nitrophenylphosphate was used as the substrate for the enzyme assay. Brain cytosolic phosphatase activity was significantly decreased by the presence of zinc or copper in the range of 10(-5) to 10(-3) M in the enzyme reaction mixture, while it was significantly increased by manganese, nickel or cobalt (10(-5) to 10(-3) M). Calcium (10(-5) to 10(-3) M) did not have an appreciable effect on brain cytosolic phosphatase activity. The inhibitory effect of zinc (10(-5) M) or copper (10(-5) M) on phosphatase activity was seen in the presence of manganese, nickel or cobalt with 10(-4) M concentration, indicating a potent inhibitory effect of these metals. Zinc or copper-decreased phosphatase activity was clearly prevented by dithiothreitol (5 mM), although the effect of each metal was further enhanced by N-ethylmaleimide (5 mM), suggesting that the metals act on the SH-groups of enzyme. Moreover, the inhibitory effect of zinc (10(-5) M) was significantly enhanced by S-100A (10(-6) M) or calbindin (10(-7) M), although neither protein had any effect in the presence of calcium (10(-5) M) or copper (10(-5) M). These results suggests that zinc has an unique role in the regulation of neutral phosphatase activity in rat brain cytosol.

Animals↗

PubMed2002

Solid state detectors in nuclear medicine.

Since Nuclear Medicine diagnostic applications are growing fast, room temperature semiconductor detectors such CdTe and CdZnTe either in the form of single detectors or as segmented monolithic detectors have been investigated aiming to replace the NaI scintillator. These detectors have inherently better energy resolution that scintillators coupled to photodiodes or photomultiplier tubes leading to compact imaging systems with higher spatial resolution and enhanced contrast. Advantages and disadvantages of CdTe and CdZnTe detectors in imaging systems are discussed and efforts to develop semiconductor-based planar and tomographic cameras as well as nuclear probes are presented.

Cadmium Compounds↗

PubMed2002

Transcription of Schizosaccharomyces pombe thioltransferase-1 in response to stress conditions.

Thioltransferase, also known as glutaredoxin, is an enzyme that catalyzes the reduction of a variety of disulfide compounds. In Schizosaccharomyces pombe, two thioltransferases were reported and the cDNA of one of the thioltransferases (thioltransferase-1) was cloned. Using a Northern blot assay, we investigated the thioltransferase transcription in response to various stress conditions. When the culture was shifted to a high temperature, the thioltransferase transcription was not significantly changed compared to the unshifted 30 degrees culture. Treatment of zinc chloride to exponentially-growing cells remarkably increased the thioltransferase transcription, whereas the treatment of mercury chloride greatly reduced the transcription. Treatment of hydrogen peroxide and cadmium chloride caused no significant effects on the transcription of the thioltransferase. These results suggest that the transcription of thioltransferase-1 in S. pombe is induced in response to metal stress that is caused by zinc chloride, but not in response to heat stress or oxidative stress that is caused by hydrogen peroxide.

Chlorides↗

PubMed2001

Zinc diphosphonates templated by organic amines: syntheses and characterizations of [NH3(CH2)2NH3]Zn(hedpH2)22H2O and [NH3(CH2)nNH3(CH2)nNH3]Zn2(hedpH)22H2O (n=4,5,6) (hedp=1-hydroxyethylidenediphophonate).

Four new zinc diphosphonate compounds with formulas [NH(3)(CH(2))(2)NH(3)]Zn(hedpH(2))(2).2H(2)O, 1, [NH(3)(CH(2))(n)()NH(3)]Zn(2)(hedpH)(2).2H(2)O, (n = 4, 2; n = 5, 3; n = 6, 4) (hedp = 1-hydroxyethylidenediphosphonate) have been synthesized under hydrothermal conditions at 110 degrees C and in the presence of alkylenediamines NH(2)(CH(2))(n)()NH(2) (n = 2, 4, 5, 6). Crystallographic data for 1: monoclinic, space group C2/c, a = 24.7422(15), b = 5.2889(2), c = 16.0338(2) A, beta = 117.903(1) degrees, V = 1856.17(18) A(3), Z = 4; 2: monoclinic, space group P2(1)/n, a = 5.4970(3), b = 12.1041(6), c = 16.2814(12) A, beta = 98.619(5) degrees, V = 1071.07(11) A(3), Z = 2; 3: monoclinic, space group P2(1)/n, a = 5.5251(2), b = 12.5968(3), c = 16.1705(5) A, beta = 99.182(1) degrees, V = 1111.02(6) A(3), Z = 2; 4: triclinic, space group P-1, a = 5.4785(2), b = 14.1940(5), c = 16.0682(6) A, alpha = 81.982(2) degrees, beta = 89.435(2) degrees, gamma = 79.679(2) degrees, V = 1217.11(8) A(3), Z = 2. In compound 1, two of the phosphonate oxygens are protonated. The metal ions are bridged by the hedpH(2)(2-) groups through three of the remaining four phosphonate oxygens, forming a one-dimensional infinite chain. The protonated ethylenediamines locate between the chains in the lattice. In compounds 2-4, only one phosphonate oxygen is protonated. Compounds 2 and 3 have a similar three-dimensional open-network structure composed of [Zn(2)(hedpH)(2)](n) double chains with strong hydrogen bonding interactions between them, thus generating channels along the [100] direction. The protonated diamines and water molecules reside in the channels. Compound 4 contains two types of [Zn(2)(hedpH)(2)](n) double chains which are held together by strong hydrogen bonds, forming a two-dimensional network. The interlayer spaces are occupied by the [NH(3)(CH(2))(6)NH(3)](2+) cations and water molecules. The significant difference between structures 2-4 is also featured by the coordination geometries of the zinc atoms. The geometries of those in 2 can be described as distorted octahedral, and those in 3 as distorted square pyramidal. In 4, two independent zinc atoms are found, each with a distorted octahedral and a tetrahedral geometry, respectively.

Journal Article↗

PubMed1997

Analytical electron microscopy as a powerful tool in plant cell biology: examples using electron energy loss spectroscopy and X-ray microanalysis.

Energy filtering transmission electron microscopy in combination with energy dispersive X-ray analysis (EDX) and quantumchemical calculations opens new possibilities for elemental and bone analysis at the ultrastructural level. The possibilities and limitations of these methods, applied to botanical samples, are discussed and some examples are given. Ca-oxalate crystals in plant cell vacuoles show a specific C K-edge in the electron energy loss spectrum (EELS), which allows a more reliable identification than light microscopical or cytochemical methods. In some dicots crystalline inclusions can be observed in different cell compartments, which are identified as silicon dioxide or calcium silicate by the fine structure of the Si L2,3-edge. Their formation is discussed on the basis of EEL-spectra and quantumchemical calculations. Examples concerning heavy metal detoxification are given for some tolerant plants. In Minuartia Zn is bound as Zn-silicate in cell walls; Armeria accumulates Cu in leaf idioblasts by chelation with phenolic compounds and Cd is precipitated as CdS/phytochelatin-complexes in tomato.

Calcium Compounds↗