Divalent Heavy Metal Ions Research Articles

Chelating Polymer Bearing 2-(2-Diazolylazo)phenol Moiety for Adsorbent of Heavy Metal Ions

Chelating polymer bearing 2-(2-diazolylazo)phenol moiety was synthesized and its metal adsorption properties for 6 divalent heavy metal ions (M2+): Co2+, Ni2+, Cu2+, Zn2+, Cd2+ and Pb2+ were investigated. The polymer changed color from orange yellow to blue or to red violet with its chelation to Cu2+ or to Ni2+, respectively. The maximum capacity of the polymer for Cu2+ was found to be 1.35 meq/ginpH 5.71 solution. The degrees of saturation of the capacity of the polymer after shaking for 30 min were 71.3 and 83.6% for the adsorptions of Zn2+ and Cu2+, respectively. The capacity of the polymer for M2+ hardly varied with the presence of alkali or alkaline earth metal ions. The elimination of metals from the polymer-M2+ chelates was achieved with 4 mol/1 HCl or 4 mol/1 H2SO4 solution.

Effect of Divalent Heavy Metal Ions on the Endocochlear Potential and Cochlear Microphonics of the Guinea-pig

Effect of Divalent Heavy Metal Ions on the Endocochlear Potential and Cochlear Microphonics of the Guinea-pig

Removal of coexisting Pb2+, Cu2+ and Cd2+ ions from water by addition of hydroxyapatite powder.

Removal of single, binary and ternary divalent heavy metal ions, i.e., Pb2+, Cu2+ and Cd2+, respectively, from their chloride or nitrate aqueous solutions was studied by the addition of hydroxyapatite in an agitated tank adsorber.The isotherms for each single component were of the rectangular type, i.e., the amounts removed from aqueous phase were constant irrespective of the concentration of solutions. For binary and ternary systems, equilibrium relations were expressed in terms of selectivity coefficient.Concentration decay curves were prepared from experimental data for comparison with theoretical calculations.Regarding mass transfer, it was found that Pb2+ was collected on the apatite structure very fast, while the two other ions showed some resistances other than film diffusion resistance.Furthermore, the apatite structure was studied by X-ray difractometry.

Effects of salts, protease digestions, chemical modifications, and heat treatment on the trypsin inhibitory activity of the protease inhibitor from Job's-tears (Coix lacryma-jobi L. var. Ma-yuen Stapf).

Trypsin inhibitor (JBTI) was extracted and purified from the bran of Job’s-tears (Coix lacryma-jobi L. var. Ma-yuen Stapf) seeds. Its molecular weight was estimated as 16500 by SDS-PAGE. Trypsin inhibitory activity of JBTI was enhanced in the presence of divalent cations, such as Ca2+ or Mg2+, and inhibited by divalent heavy metal ions, such as Cu2+ or Zn2 + . Its activity was stable against pepsin digestion, while JBTI was denatured by subtilisin BPN or Actynase E digestions. Its activity was stable against chemical modification of the lysyl residues, while JBTI lost its activity by the modification of the arginyl residues. The thermal unfolding of JBTI was studied in an adiabatic differential scanning calorimeter and it was found that the protein unfolds at 93°C and pH 7.0 in 50 mm phosphate buffer.

Preventive effects of zinc on cadmium-induced inhibition of alkaline phosphatase activity and mineralization activity in osteoblast-like cells, MC3T3-E1.

In order to determine the specific action of cadmium on bone metabolism, the effect of cadmium on alkaline phosphatase activity, a marker enzyme of osteoblasts, was compared with that of other divalent heavy metal ions, i.e., zinc, manganese, lead, copper, nickel and mercury (10 microM each), using cloned osteoblast-like cells, MC3T3-E1. Cadmium had the strongest inhibitory effect on alkaline phosphatase activity of the cells among the metals tested. At the same dose, however, cadmium failed to inhibit cellular glucose-6-phosphatase and lactate dehydrogenase activities, suggesting that the inhibitory effect of cadmium on alkaline phosphatase was specific and was not dependent on cell injury. Cadmium treatment caused a significant decrease in cellular zinc level, but mercury treatment had no such effect at the dose inhibiting alkaline phosphatase activity. There was a good correlation between decrease of cellular zinc level and inhibition of alkaline phosphatase activity in cadmium-treated cells. Concomitant treatment of the cells with zinc prevented the cadmium-induced inhibition of alkaline phosphatase activity. However, this was not the case in the mercury-induced inhibition. Cadmium also inhibited the mineralization of osteoblasts. When 10 or 20 microM zinc was concomitantly added to the cultures, the inhibition of mineralization was prevented. These data suggest that the inhibitory effect of cadmium in osteoblasts may be closely related to its influence on the cellular zinc metabolism.

Effects of divalent cations on chloride movement across amphibian skin.

Effects of the divalent heavy metal ions Cd2+, Co2+, Cu2+, Mn2+, Ni2+, and Zn2+ on pathways for sodium and chloride were assessed on isolated amphibian skin (Rana temporaria and esculenta, Bufo marinus and viridis). It was observed that these agents, in addition to the previously reported stimulation of sodium transport, inhibit chloride-related tissue conductance (gCl) in frog skin with spontaneously high gCl when added to the external incubation medium. Serosal application was ineffective. Half-maximal inhibition of gt occurred at approximately 0.2 mmol/l Ni2+ and Zn2+, 0.5 mmol/l Co2+ and Cd2+, and more than 3 mmol/l Mn2+. The onset of inhibition was rapid, steady state values being reached within 3 min; reversibility was complete with approximately similar time course. Cu2+, which could not be tested at concentrations above 0.1 mmol/l, had only minimal and poorly reversible effect on gCl. Skin of Bufo was virtually insensitive to these metal ions. Microelectrode determinations demonstrate that the decrease of conductance was restricted to a pathway distinct from the principal cells which show, on the contrary, increase of apical membrane conductance originating from stimulation of sodium permeability. The metal ions might be valuable for characterization of the pathway and the mechanism of transepithelial conductive chloride transport.

The Effect of Nicotianamine on the Uptake of Mn2+, Zn2+, Cu2+, Rb+ and PO3-4 by the Tomato Mutant chloronerva

Summary In addition to its excessive iron uptake the mutant chloronerva also accumulates higher concentrations of Mn2+, Zn2+ and Cu2+ than the wild-type. This extra uptake decreases after application of nicotianamine either to the nutrient solution or to the leaves of mutant seedlings. Contrary to these ions the rate of Rb+ and PO43- uptake is higher in the wild-type than in the mutant where nicotianamine seems to exert a stimulating effect. It is suggested that the role of nicotianamine is not confined to iron uptake but is generally aimed at divalent heavy metal ions. It is active in plant species where “strategy I” of iron acquisition is realized, but it is not a phytosiderophore.

Chelating polymer bearing triazolylazophenol moiety as the functional group

AbstractThe chelating polymer‐bearing triazolylazophenol moiety as the functional group was synthesized, its metal adsorption properties for 6 divalent heavy metal ions; Co2+, Ni2+, Cu2+, Zn2+, Cd2+, and Pb2+ were investigated. The capacity of the polymer for Cu2+ achieved 8.7 mEq/g in pH 5.3 solution. The polymer showed remarkable color changes from orange to red violet or blue violet with its chelations to the heavy metal ions. The metal adsorption rates of the polymer were rapid in performing complete capacity saturation of heavy metal ions in about 30 min. The capacities varied little the presence of alkali or alkaline earth metal ions in solutions. The perfect elimination of metals from the polymer–M2+ chelates were performed with mineral acid solutions. The metal ions; Cu2+ and Ni2+ in plating‐process solutions were effectively removed by the chelating polymer, and the polymer can be practically used for the removal of these ions from waste water.

Ethane production of mouse peritoneal macrophages as indication for lipid peroxidation and the effect of heavy metals

Mouse peritoneal macrophages cultivated for 24 h produced ethane which is a new index for lipid peroxidation reactions, whereas malondialdehyde (MDA), an alternative method, did not increase. This is explained by the metabolism of MDA by macrophages after addition of MDA, whereas the gaseous ethane added remained constant. This indicates that ethane rather than MDA is a reliable parameter for lipid peroxide formation by macrophages. Divalent heavy metal ions were examined for their effect on ethane formation and on cell viability. Whereas the amount of ethane formed by macrophages in presence of CdCl 2 and MnCl 2 remained fairly constant, PbCl 2 and ZnCl 2 resulted in decreased ethane production up to 60%. But with all these metals the viability decreased much more and did not correlate with the ethane formation. With some concentrations of FeCl 2 an increased ethane formation was observed which was accompanied by decreased viability of the cells. The results are consistent with the view that heavy metals interfere with the oxygen radical reactions of macrophages, and that viability of macrophages is not closely related to these oxidative reactions.

Bacteriophage T4D receptors and the Escherichia coli cell wall structure: role of spherical particles and protein b of the cell wall in bacteriophage infection

The nature of the interaction of bacteriophage T4D and the outer cell wall of its host, Escherichia coli B, has been investigated. Bacteria with altered or modified cell walls have been obtained by two different growth procedures: (i) growth in high osmolarity medium or (ii) growth in broth in the presence of divalent heavy metal ions. When these altered host cells were washed and subsequently added to regular growth medium, they interacted with added phage particles, but successful infection did not occur. Most of the phage particles released from these treated cells were observed to have full heads and an altered tail structure. The altered phage tails had contracted sheaths and unusual pieces of the bacterial cell wall attached to the distal portion of the exposed phage tail tube. Phage released from bacteria grown in the high osmolarity medium had attached cell wall pieces of two major types, these pieces being either 40 or 21 nm in diameter. The smaller-type cell wall pieces (21 nm) were formed by three spheres each measuring 7 nm in diameter. Phage particles released from cells previously exposed to the divalent metal ions had only one 7-nm cell wall sphere attached to the distal end of the tail tube. It was found that these 7-nm spheres (i) are normal components of the cell wall and are morphologically similar to endotoxin, (ii) are held in place on the cell wall by a component of the cell wall called protein b, and (iii) are most likely the site of penetration of the phage tail tube through which the phage DNA enters the host cell.

Calcium-binding of synaptosomes isolated from rat brain cortex, III. Binding with some divalent heavy metal ions and calcium-binding sites.

Free ion concentration of some divalent heavy metal ions such as Mn2+, Co2+, Ni2+, Cd2+ and Zn2+ in the synaptosomal suspension was measured to determine binding with synaptosomes isolated from rat brain cortex. A dual wavelength spectrophotometer was utilized to monitor the absorbance changes of murexide raised by stepwise addition of these ions (as chloride salts). Such titration experiments of the synaptosomal suspension revealed that a part of the added divalent cation such as Mn2+, Co2+ or Ni2+ was almost instantaneously bound to synaptosomes in isotonic NaCl media. Our previous study (Kamino, Uyesaka & Inouye, J. Membrane Biol. 17:13, 1974) demonstrated that raised external K+ resulted in a specific noncompetitive inhibition of synaptosomal Ca-binding. Just like the Ca-binding, Mn-, Co- or Ni-binding was almost completely depressed by high external K+ or ruthenium red when the free concentration of the cations was 10 mum or less, while at higher concentrations the binding was not affected. The present results indicate that tested divalent cations bind with both "Ca-binding sites" and "non-Ca-binding sites" of synaptosomal membrane, the nature of the binding sites of both being quite different: the former is sensitive to high external K+ and to ruthenium red but the latter is not.

The reaction of amino alcohols with active esters: II. Catalysis of the acylation step by metal ions

The reaction of triethanolamine (TEA) with active substrates— p-nitrophenyl esters and cinnamoyl imidazole (CI)—is catalyzed by divalent heavy metal ions. With Hg 2+, rate enhancements of 100–1000 (depending on the substrate) were observed, the overall rate constants of substrate decomposition thus exceeding those of spontaneous hydrolysis up to 100,000-fold. The predominant active species at low L:M ratio was found to be the Hg-(TEA) 2 complex. The dependence of the reaction rate upon excess of amino alcohol—at constant Hg 2+ concentration—is attributable to formation of another active complex—Hg-(TEA) 3. The high reactivity of the system is due to the alcoholate group of metal-bound TEA, whose p K has been lowered by the proximity of the metal ion. This labile nucleophilic alcoholate attacks the substrate causing its alcoholysis and forming O-acyl-TEA. The lability of the metal-alcoholate bond can be enhanced by low concentrations of halide ions, thus causing up to 5-fold additional increase in alcoholysis rate. Higher halide ion concentrations cause inhibition, probably due to formation of inactive HgX 2 molecules. Presumably an important role of the metal ion in metalloenzymes is to affect the decrease in the p K value of a reactive group so that it can exhibit activity under physiological conditions.