Construction of fluorescent probes for zinc ion (Zn2+) and cadmium ion (Cd2+) is significant for the safety of humans. However, the discriminating recognition of Zn2+ and Cd2+ by a single probe remains challenging owing to their similar properties. Herein, a novel deoxycholic acid derivative containing 8-hydroxyquinoline fluorophore has been facilely synthesized through click chemistry to form a clamp-like probe. Using its perfect bonding cavity from 1,2,3-triazole and quinoline, this molecule showed favorable solvent-dependent fluorescent responses and distinguished Zn2+ and Cd2+ in different solvents. In ethanol aqueous solution, it displayed good selectivity and ratiometric fluorescence to Zn2+ with 30 nm spectroscopic red-shifts. In acetonitrile aqueous solution, it exhibited good selectivity and ratiometric fluorescence to Cd2+ with 18 nm spectroscopic red-shifts. Moreover, the unique microstructural features of the probe in assembly were used to reflect its recognition processes. Due to its merits of low detection limit and instant response time, the probe was utilized for sensing Zn2+ and Cd2+ in water, beer and urine with high accuracy. Meanwhile, this probe served as a handy tool and was employed to obtain inexpensive test strips for the prompt and semiqualitative analysis of Zn2+ and Cd2+ with the naked eye. 相似文献
A quinolinocyclodextrin, that is, MQAS-β-cyclodextrin (MQAS = N-(2-methyl-8-amino- quinolyl)-p-aminobenzene sulfonamide) was synthesized. Further experiments showed that it could form very stable stoichiometric 2:1 complex with Zn2+ in water. Significantly, the resultant quinolinocyclodextrin/Zn2+ complex showed the specific fluorescence response to Hg2+ over other metal ions, which could be readily distinguished in either aqueous solution or the PVA-based thin film. This finding would enable Zn·32 complex as a convenient and highly efficient fluorescence sensor for the detection of Hg2+. 相似文献
Exposure of Helianthus annuus L. seedlings to Al3+, Cd2+ or Zn2+ resulted in a marked decrease of fresh and dry masses of the shoots and the roots. The increase of Al3+, Cd2+ or Zn2+ uptake was accompanied by a significant decrease of nitrate, phosphorus and K+ uptake. There was a significant increase of malic and citric acid contents in the shoots and roots of heavy metal-treated
seedlings whereas the change in fumaric acid was insignificant. Al3+ and Zn2+ alone stimulated excretion of malic and citric acids to the rhizosphere. Addition of high concentrations of malic or citric
acid alleviate to some extent the inhibitory effect of Al3+ and Zn2+ on plant growth.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
Removal of heavy metals (Pb2+, Zn2+) from aqueous solution by dried biomass of Spirulina sp. was investigated. Spirulina rapidly adsorbed appreciable amount of lead and zinc from the aqueous solutions within 15 min of initial contact with the
metal solution and exhibited high sequestration of lead and zinc at low equilibrium concentrations. The specific adsorption
of both Pb2+ and Zn2+ increased at low concentration and decreased when biomass concentration exceeded 0.1 g l−1. The binding of lead followed Freundlich model of kinetics where as zinc supported Langmuir isotherm for adsorption with
their r2 values of 0.9659 and 0.8723 respectively. The adsorption was strongly pH dependent as the maximum lead biosorption occurred
at pH 4 and 10 whereas Zn2+ adsorption was at pH 8 and 10. 相似文献
A reversible and easy assembled fluorescent sensor based on calix[4]arene and phenolphthalein (C4P) was developed for selective zinc ion (Zn2+) sensing in aqueous samples. The probe C4P demonstrated high selective and sensitive detection towards Zn2+ over other competitive metal ions. Interaction of Zn2+ with a solution of C4P resulted in a considerable increment in emission intensity at 440 nm (λex = 365 nm) due to the suppression of photoinduced electron transfer (PET) process and the restriction of C=N isomerization . The binding constant (Ka) of C4P with Zn2+ was calculated to be 4.50 × 1011 M?2 and also the limit of detection of C4P for Zn2+ was as low as 0.108 μM (at 10?7 M level). Moreover, the fluorescence imaging in the human colon cancer cells suggested that C4P had great potential to be used to examine Zn2+in vivo. 相似文献
An inducible enzyme catalysing the hydrolysis of (+)-usnic acid to (+)-2-desacetylusnic acid and acetic acid has been purified 150-fold from the mycelium of Mortierella isabellina grown in the presence of (+)-usnic acid. Purification was achieved by treatment with protamine sulfate, (NH4)2SO4 fractionation, negative adsorption on alumina Cγ gel and hydroxylapatite followed by chromatography on DEAE-cellulose and Sephadex G-200. The elution pattern from a Sephadex G-200 column indicated a MW of ca 7.6 × 104 for the enzyme. The apparent Km value for (+)-usnic acid at the pH optimum (pH 7) was 4.0 × 10?5 M. The enzyme was specific for (+)-usnic acid and inactive towards (?)-usnic acid, (+)-isousnic acid or certain phloracetophenone derivatives. Its activity was enhanced in the presence of divalent metal ions such as Co2+, Ni2+, Mn2+, Mg2+ and Zn2+. 相似文献
Sorption of Cu2+ and Zn2+ to the plasma membrane (PM) of wheat root (Triticum aestivum Lcv. Scout 66) vesicles was measured at different pH values and in the presence of organic acids and other metals. The results were analyzed using a Gouy-Chapman-Stem model for competitive sorption (binding and electrostatic attraction) to a negative binding site. The binding constants for the two investigated cations as evaluated from the sorption experiments were 5 M–1 for Zn2+ and 400 M–1 for Cu2+. Thus, the sorption affinity of Cu2+ to the PM is considerably larger than that of Ca2+, Mg2+ or Zn2+. The greater binding affinity of Cu2+ was confirmed by experiments in which competition with La3+ for sorption sites was followed. The amount of sorbed Cu2+ decreased with increasing K+, Ca2+, or La3+ concentrations, suggesting that all these cations competed with Cu2+ for sorption at the PM binding sites, albeit with considerable differences among these cations in effectiveness as competitors with Cu2+. The sorption of Cu2+ and Zn2+ to the PM decreased in the presence of citric acid or malic acid. Citric acid (as well as pH) affected the sorption of Cu2+ or Zn2+ to PM more strongly then did malic acid. 相似文献
Human transthyretin (TTR) is a homotetrameric protein involved in several amyloidoses. Zn2+ enhances TTR aggregation in vitro, and is a component of ex vivo TTR amyloid fibrils. We report the first crystal structure of human TTR in complex with Zn2+ at pH 4.6–7.5. All four structures reveal three tetra-coordinated Zn2+-binding sites (ZBS 1–3) per monomer, plus a fourth site (ZBS 4) involving amino acid residues from a symmetry-related tetramer that is not visible in solution by NMR. Zn2+ binding perturbs loop E-α-helix-loop F, the region involved in holo-retinol-binding protein (holo-RBP) recognition, mainly at acidic pH; TTR affinity for holo-RBP decreases ∼5-fold in the presence of Zn2+. Interestingly, this same region is disrupted in the crystal structure of the amyloidogenic intermediate of TTR formed at acidic pH in the absence of Zn2+. HNCO and HNCA experiments performed in solution at pH 7.5 revealed that upon Zn2+ binding, although the α-helix persists, there are perturbations in the resonances of the residues that flank this region, suggesting an increase in structural flexibility. While stability of the monomer of TTR decreases in the presence of Zn2+, which is consistent with the tertiary structural perturbation provoked by Zn2+ binding, tetramer stability is only marginally affected by Zn2+. These data highlight structural and functional roles of Zn2+ in TTR-related amyloidoses, as well as in holo-RBP recognition and vitamin A homeostasis. 相似文献
The ability of the filamentous fungus Verticillium marquandii for Zn2+ and Pb2+ uptake from aqueous solution was studied. The 24-h-old living mycelium bound Zn2+ and Pb2+ (206.2 and 324.5 mg/g dry weight, respectively) effectively, in contrast to a very low Zn2+ uptake by autoclaved mycelium (20.2 mg/g). The most effective results were noted when the metals were introduced as acetates
and incubated with mycelium for 24 h in case of Zn2+ while Pb2+ achieved the maximum level of metal binding after as early as 3 h. The cell wall was the main site of effective Zn2+ and Pb2+ binding by V. marquandii mycelium (91.0–93.6% of metals were located in cell wall after 24 h of exposure). The metabolic inhibitors: antimycin A and
sodium azide had a strong limitation effect on Zn2+ uptake by a 24-h-old living mycelium, whereas Pb2+ binding did not decrease to a large extent. The freshly obtained protoplasts accumulated Zn2+ and Pb2+ on a low level in comparison with cells at different stages of cell wall regeneration. The use of regenerating protoplasts
showed that resynthesis of cell wall was necessary for high binding of Zn2+, whereas Pb2+ uptake on the significant level took place during cell wall regeneration.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
Addition of Zn2+_ to cell medium inhibited the induction of ornithine decarboxylase (ODC) activity in ODC overproducing L1210-DFMOr cells. A significant effect was observed at a concentration as low as 0.01 mM, however a more marked inhibition was caused by the addition of 0.1 mM Zn2+. The inhibition of the induction of ODC activity was accompanied by a proportional decrease in the content of immunoreactive ODC protein, whereas the level of ODC mRNA, detemined by a solution hybridization RNase protection assay, was not affected signigicantly. Instead, some acceleration of ODC turnover was observed. the addition of 0.1 mM Co2+ or Mn2+, but not of other divalent metal ions, also inhibited ODC induction; differently from Zn2+ however, these metals affected cell viability and/or cell growth. Removal of endogenous Zn2+ by a chelator also provoked a strong decrease of ODC induction, which was reversed by Zn2+. However, addition of Zn2+ in excess of the chelator proved to be markedly inhibitory. These results indicate that both a restricted Zn2+ availability and an enhanced presence of the metal can inhibit the induction of ODC in L1210-DFMOr cells. 相似文献
Addition of microgram quantities (5–10 μg per 2 ml) of Mn2+, Fe2+, and Mo2+ increases the intensity of color developed by amino acids two- to three-fold when reacting with ninhydrin. The lowest limit detected by the increased sensitivity of the reaction is 3 nmol of an amino acid. Cd2+, Zn2+, and Al3+ depress the color formation due to reaction between amino acids and ninhydrin. When chromatograms of amino acids are first sprayed with aqueous manganese chloride and later with ninhydrin or with ninhydrin solution containing manganese, not only is the sensitivity increased, but the stained spots retain their color for longer periods. 相似文献
The nature of the interaction between polyacrylalc ion and several divalent cations, such as Cu2+, Mn2+, Zn2+, Ba2+ and Mg2+, was investigated using Raman spectroscopy. A specific Raman band characteristic of a carboxyl group is shifted upon addition of Cu2+. Zn2+ and Mn2+ to partially neutralized poly(acrylic acid). On the other hand. no frequency shift of the specific Raman band is observed on addition of Mg2+ and Ba2+*, though the intensity of the specific Raman band decreases with concentration of MgCl2. It is concluded from these Raman data that the interaction between polyacrylatc ion and Cu2+. Zn2+ or Mn2+ includes a specific interaction with bond formation, whereas in the case of Mg2+ and Ba2+, the electrostatic interaction is dominant. 相似文献
Dipicolinic acid synthesis inPenicillium citreoviride strain 3114 was inhibited by Ca2+ ions, but not by Ba2+, Cu2+or Fe2+. Among the metals tested, only Zn2+ inhibited the synthesis of dipicolinic acid and promoted sporulation. None of these metals reversed the inhibition by Ca2+ or Zn2+. A mutant 27133-dpa-ca selected for resistance to feedback inhibition by dipicolinic acid: Ca2+ complex showed cross-resistance to inhibition by dipicolinic acid: Zn2+. Both 3114 and271 33-dpa-ca excreted a number of aliphatic and amino acids during secondary metabolism of dipicolinic acid. In the presence of 1000 ppm
of Ca2+, accumulation of citric acid and α-aminoadipic acid was completely inhibited under conditions of inhibition of dipicolinic
acid in parent strain 3114 but not in the mutant. Citric acid with or without Ca2+ did not inhibit thede novo synthesis of dipicolinic acid in the strain 3114. In fact, citric acid in the presence of Ca2+ improved significantly rate of dipicolinic acid synthesis. Apart from resistance to feed back inhibition by dipicolinic acid:
Ca2+ complex, mutant differed from the parent in three other aspectsviz. (i) dipicolinic acid synthesis was not subject to catabolite repression by glucose, (ii) sporulation as well as dipicolinic
acid synthesis was dependent on the presence of Ca2+ ions in the medium and (iii) Mg2+ requirement for the mutant increased three fold. Higher requirement of the Mg2+ could be partially relieved by Ca2+ during secondary metabolism. The results support the inference thatde novo synthesis of dipicolinic acid is regulated through feedback inhibition by dipicolinic acid: Ca2+complex. 相似文献
A di-N-functionalized 14-membered tetraaza macrocycle, [H4L3](ClO4)2 (L3 = 1,8-bis(2-carboxyethyl)-3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradecane), has been synthesized by acid hydrolysis of 1,8-bis(2-cyanoethyl)-3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradecane (L2). The copper(II) complexes [CuL2](ClO4)2 and [Cu(H2L3)](ClO4)2 were prepared and characterized. The complex [Cu(H2L3)]2+ readily reacts with methanol to yield [CuL4]2+ (L4 = 1,8-bis(2-carbomethoxyethyl)-3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradecane). The N-CH2CH2COOH groups of [Cu(H2L3)](ClO4)2 are not coordinated to the metal ion in the solid state but are involved in coordination in various non-aqueous solvents or in aqueous solutions of pH ? 1.0. Interestingly, [CuL4](ClO4)2 exists as two stable structural isomers, 1 (the pendant ester groups are not involved in coordination) and 2 (one of the two ester groups is coordinated to the metal ion), in the solid state; the two isomers can be prepared selectively by controlling ionic strength of a methanol solution of the complex. Crystal structures and coordination behaviors of the two isomers are described. The di-N-cyanoethylated macrocyclic complex [CuL2](ClO4)2 is rapidly decomposed in 0.1 M NaOH solution even at room temperature. On the other hand, [Cu(H2L3)](ClO4)2 and [CuL4](ClO4)2 are quite inert against decomposition under similar basic conditions. In acidic or basic aqueous solutions, [CuL4]2+ is hydrolyzed to [Cu(H2L3)]2+ or [CuL3]. 相似文献
The acute effects of aqueous solutions of As, Cd, Cu, Pb, F, and Zn ions at concentrations from 0.01 to 100 micrograms per milliliter and solutions adjusted to pH 2 to 6 with nitric or sulfuric acid were studied with respect to acetylene reduction, net photosynthesis, respiration rate, and chlorophyll content in Vernal alfalfa (Medicago sativa L. cv. Vernal). The effects of the various treatments on acetylene reduction varied from no demonstrable effect by any concentration of F− and 42% inhibition by 100 micrograms Pb2+ per milliliter, to 100% inhibition by 10 micrograms Cd2+ per milliliter and 100 micrograms per milliliter As, Cu2+, and Zn2+ ions. Zn2+ showed statistically significant inhibition of activity at 0.1 micrograms per milliliter. Acid treatments were not inhibitory above pH 2, at which pH nitric acid inhibited acetylene reduction activity more than did sulfuric acid. The inhibition of acetylene reduction by these ions was Zn2+ > Cd2+ > Cu2+ > AsO3− > Pb2+ > F−. The sensitivity of acetylene reduction to the ions was roughly equal to the sensitivity of photosynthesis, respiration, and chlorophyll content when Pb2+ was applied, but was 1,000 times more sensitive to Zn2+. The relationship of the data to field conditions and industrial pollution is discussed. 相似文献
Herein, a boronic acid-based sensor was reported selectively to recognize Pd2+ ion. The fluorescence intensity increased 36-fold after sensor binding with 2.47 × 10−5 M of Pd2+ ion. It was carried out in the 99% aqueous solution for binding tests, indicating sensor having good water solubility. In addition, it is discernible that Pd2+ ion turned on the blue fluorescence of sensor under a UV–lamp (365 nm), while other ions (Ag+, Al3+, Ba2+, Ca2+, Cr2+, Cd2+, Co2+, Cs2+, Cu2+, Fe2+, Fe3+, K+, Li+, Mg2+, Mn2+, Na+, Ni2+ and Zn2+) did not show the similar change. Furthermore, sensor has a low limit of detection (38 nM) and high selectivity, which exhibits the potential for the development of Pd2+ recognition in practical environments. 相似文献
Dolomite collected from Surat Thani Province in Thailand was investigated for use as a sorbent for the removal of divalent heavy metal cations from an aqueous solution. The sorbent had a surface area of 2.46 m2/g and a pH of zero point charge (pHzpc) of 9.2. Batch sorption was used to examine the effect of the pH (pH 3–7) on the sorption capacity of Cd2+, Pb2+ and Zn2+, alone or together as an equimolar mixture at various concentrations. Alone, each heavy metal cation was adsorbed faster at a higher pH, where the sorption of Cd2+ and Pb2+ fitted a Langmuir isotherm, but Zn2+ sorption best fitted a Freundlich isotherm. Under equimolar competitive sorption, the sorption capacity of each cation was decreased by 75.8% (0.29–0.07 mM/g), 82.8% (0.53–0.09 mM/g), and 95.7% (0.84–0.04 mM/g) for Cd2+, Pb2+ and Zn2+, respectively, compared to that with the respective single cation. Desorption of these heavy metal cations from dolomite was low, with an average desorption level of 0.06–17.4%. Furthermore, since dolomite is readily available and rather cheap, it is potentially suitable for use as an efficient sorbent to sorb Cd2+ and Pb2+, and perhaps Zn2+, from contaminated water. 相似文献
In cultured cortical and hippocampal neurons when intracellular pH drops from 6.6 to 6.1, yet unclear intracellular stores release micromolar amounts of Zn2+ into the cytosol. Mitochondria, acidic organelles, and/or intracellular ligands could release this Zn2+. Although exposure to the protonophore FCCP precludes reloading of the mitochondria and acidic organelles with Zn2+, FCCP failed to compromise the ability of the intracellular stores to repeatedly release Zn2+. Therefore, Zn2+‐releasing stores were not mitochondria or acidic organelles but rather intracellular Zn2+ ligands. To test which ligands might be involved, the rate of acid‐induced Zn2+ release from complexes with cysteine, glutathione, histidine, aspartate, glutamate, glycine, and carnosine was investigated; [Zn2+] was monitored in vitro using the ratiometric Zn2+‐sensitive fluorescent probe FuraZin‐1. Carnosine failed to chelate Zn2+ but did chelate Cu2+; the remaining ligands chelated Zn2+ and upon acidification were releasing it into the medium. However, when pH was decreasing from 6.6 to 6.1, only zinc–cysteine complexes rapidly accelerated the rate of Zn2+ release. The zinc–cysteine complexes also released Zn2+ when a histidine‐modifying agent, diethylpyrocarbonate, was applied at pH 7.2. Since the cytosolic zinc–cysteine complexes can contain micromolar amounts of Zn2+, these complexes may represent the stores responsible for an acid‐induced intracellular Zn2+ release.