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1.
Bacillus thuringiensis is the major source for transfer of genes to impart insect resistance in transgenic plants. Cry2A proteins of B. thuringiensis are promising candidates for management of resistance development in insects owing to their difference from the currently used Cry1A proteins, in structure and insecticidal mechanism. The cry2Ab gene was found to lack a functional promoter and, hence, is cryptic in nature. The cry2Ab7 gene was cloned from a new indigenous B. thuringiensis strain, 14-1. Nucleotide sequencing of the cry2Ab gene cloned from B. thuringiensis strain 14-1 revealed an open reading frame of 1902 bp. The deduced amino acid sequence of Cry2Ab of B. thuringiensis strain 14-1 showed a variation in three amino acid residues in comparison to the holotype sequence, Cry2Ab1. Expression of the newly cloned cry2Ab gene was studied in an acrystalliferous strain of B. thuringiensis (4Q7) by fusing the cry2Ab gene downstream of cry2Aa promoter and orf1+orf2 sequences. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of a spore-crystal mixture obtained from transformants of B. thuringiensis strain 4Q7 showed production of Cry2Ab protein of about 65 kDa. Alkali solubilized Cry2Ab7 protein showed toxicity against Helicoverpa armigera neonates.  相似文献   

2.
This work describes the development of a heavy-metal biosensor based on either recombinant 6His-Tag glutathione S-transferase (GST-(His)6) or glutathione S-transferase Theta 2-2 (GST-theta 2-2), and a capacitive transducer. The dynamic range of the pure bovine liver GST-Theta 2-2 biosensor was 1?fM to 1?mM for Zn2+, and 10?pM to 1?mM for Cd2+. The GST-(His)6 biosensor was able to detect Zn2+ and Cd2+ in the range of 1?fM to 10?µM, and Hg2+ in the range of 1?fM to 10?mM. The bovine liver GST Theta 2-2 biosensor displays an increased selectivity and a wider dynamic range for Zn2+ compared with the GST-(His)6 biosensor. Therefore, by using different GST isozymes, it is possible to modulate important characteristics of capacitive biosensors for the detection of heavy metals.  相似文献   

3.
Hexa-histidine (6His) peptide was inserted to a permissive site of the surface layer (S-layer) protein RsaA of Caulobacter crescentus. The recombinant strain JS4022/p723–6H, expressing RsaA-6His fusion protein was examined for its ability to sequester Cd(II) from the bacterial growth medium. When mixed with 1 ppm CdCl2, JS4022/p723–6H removed 94.3 ∼ 99.9% of the Cd(II), whereas the control strain removed only 11.4 ∼ 37.0%, depending on experimental conditions. The effective contact time of the cells and Cd(II) was as short as 15 min. When higher concentrations of CdCl2 were tested, JS4022/p723–6H consistently demonstrated enhanced binding capacity over the control strain. At 15 ppm of Cd(II), each gram of JS4022/p723–6H dry cells retrieved 16.0 mg of Cd(II), comparing to 11.6 mg g−1 achieved by the control strain. This work provides a potential cost-effective solution toward bioremediation of heavy metals from aqueous systems.  相似文献   

4.
The complexation reactions between Mg2+, Ca2+, Ag+ and Cd2+ metal cations with N-phenylaza-15-crown-5 (Ph-N15C5) were studied in acetonitrile (AN)–methanol (MeOH), methanol (MeOH)–water (H2O) and propanol (PrOH)–water (H2O) binary mixtures at different temperatures using the conductometric method. The conductance data show that the stochiometry of all of the complexes with Mg2+, Ca2+, Ag+ and Cd2+ cations is 1:1 (L:M). The stability of the complexes is sensitive to the solvent composition and a non-linear behaviour was observed for variation of log K f of the complexes versus the composition of the binary mixed solvents. The selectivity order of Ph-N15C5 for the metal cations in neat MeOH is Ag+>Cd2+>Ca2+>Mg2+, but in the case of neat AN is Ca2+>Cd2+>Mg2+>Ag+. The values of thermodynamic parameters (ΔH c o , ΔS c o ) for formation of Ph-N15C5–Mg2+, Ph-N15C5–Ca2+, Ph-N15C5–Ag+ and Ph-N15C5–Cd2+ complexes were obtained from temperature dependence of stability constants and the results show that the thermodynamics of complexation reactions is affected by the nature and composition of the mixed solvents.  相似文献   

5.
The unit cell edge length, a, of a set of complex cubic perovskites having the general formula A 2 2+ BB′O6 is predicted using two methodologies: multiple linear regression and artificial neural neworks. The unit cell edge length is expressed as a function of six independent variables: the effective ionic radii of the constituents (A, B and B′), the electronegativities of B and B′, and the oxidation state of B. In this analysis, 147 perovskites of the A 2 2+ BB′O6 type, having the cubic structure and belonging to the Fm3m space group, are included. They are divided in two sets; 98 compounds are used in the calibration set and 49 are used in the test set. Both models give consistent results and could be successfully use to predict the lattice cell parameter of new members of this series.  相似文献   

6.
The molecular and electronic structures of closo-hexaboranes B6H6 2–, B6H7 , and B6H8 and closo-heterohexaboranes XYB4H4 (X = Y = CH, N; X = BH, Y = CH, N, NH, O) were studed by the ab initio (MP2(full)/6-311+G**) and density functional (B3LYP/6-311+G**) methods. The bridging H atoms in closo-hexaboranes B6H7 and B6H8 can undergo facile low-barrier migrations around the boron cage (the barrier heights are about 10—15 kcal mol–1). All heteroboranes having octahedron-like structures with hypercoordinated N and O atoms are rather stable and can be the subject of synthetic research efforts.  相似文献   

7.
A relation was established between the composition of Cd x Zn1–x S nanoparticles and their ability to accumulate excess negative charge during irradiation. The rate of expenditure of the accumulated charge depends on the composition of the nanoparticles and is determined by their electric capacitance. A correlation was found between the photocatalytic activity of the Cd x Zn1–x S nanoparticles in the release of hydrogen from solutions of Na2SO3, their composition, and their capacity for photoinduced accumulation of excess charge. It was shown that Ni0 nanoparticles photodeposited on the surface of Cd x Zn1–x S are effective cocatalysts for the release of hydrogen. It was found that ZnII additions in photocatalytic systems based on Cd x Zn1–x S/Ni0 nanostructures have a promoting action on the release of hydrogen from water–ethanol mixtures. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 45, No. 1, pp. 8–16, January-February, 2009.  相似文献   

8.
The transport experiments of Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Ag+ and Pb2+ metal cations were carried out by dibenzo-18-crown-6 (DB18C6), dibenzyl-diaza-18-crown-6 (Dibenzyl-diaza-18C6) and di-tert-butyl-dibenzo-18-crown-6 (Di-tert-butyl-DB18C6) using chloroform (CHCl3), 1,2-dichloroethane (1,2-DCE) and nitrobenzene (NB) organic solvents as liquid membranes. The source phase contained equimolar concentration of these metal cations and the source and receiving phases being buffered at pH=5 and pH=3, respectively. The obtained results show that the selectivity and the efficiency of transport for these heavy metal cations change with the nature of the ligand and also the organic solvents, which were used as liquid membranes in these experiments. A good selectivity was observed for silver (I) ion by dibenzyl-diaza-18C6 in all membrane systems. Dibenzo-18C6 and di-tert-butyl-DB18C6 showed the highest transport efficiency for cobalt (II) ion. The effect of stearic acid on transport efficiency was also investigated and the results show that the efficiency of transport of the heavy metal cations increases in the presence of this organic acid.  相似文献   

9.
Ab initio calculations of aquacomplexes of the ions of Group IB−IVB metals in anomalous oxidation states (2S1/2 electron state) were carried out by the Becke-Le-Yang-Parr (BLYP) density functional method using the Dunning-Hay DZ basis set. Optimum geometric parameters and electronic characteristics were determined of aquacomplexes M(H2O) n z+, where Mz+=Au0 (n=2, 4); Ag0, Cu0 (n=2, 4, 6); Zn1+, Cd1+, Hg1+ (n=4, 6); Ga2+, In2+, Tl2+ (n=6); and Ge3+, Sn3+, Pb3+ (n=6). The spin corresponding periods. The energy of transition of the unpaired electron to the first vacant level increases in the same order. The results of calculations are in agreement with experimental data obtained by ESR and optical spectroscopy. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 858–864, May, 1999.  相似文献   

10.
In order to explore the reuse properties of oxidized chelating resin containing sulfur after adsorption, two kinds of novel chelating resins, poly[4-vinylbenzyl-(2-hydroxyethyl)] sulfoxide (PVBSO) and poly[4-vinylbenzyl-(2-hydroxyethyl)] sulfone (PVBSO2), were synthesized using poly[4-vinylbenzyl-(2-hydroxyethyl)] sulfide (PVBS) as material. Their structures were confirmed by FTIR and XPS. The adsorption properties and mechanism for metal ions such as Au3+, Pt4+, Pd2+, Hg2+, Cu2+, Ni2+, Fe3+, Pb2+, Cd2+, and Zn2+ were investigated. Experimental results showed that PVBSO had good adsorption and selective properties for Au3+, Pd2+ and Cu2+ when the coexisting ion was Pt4+, Ni2+, Pb2+ or Cd2+. In the aqueous system containing Cu2+ and Pb2+ or Cu2+ and Cd2+, PVBSO2 only adsorbed Cu2+. The selective coefficients of PVBSO and PVBSO2 were αAu/Pt = 4.8, αAu/Pd = 11.8, αPd/Pt = 10.9, αCu/Ni = 2.5, αCu/Cd = 41.2, αCu/Pb = ∞, αCu/Ni = 3.0, αCu/Cd = ∞, αCu/Pb = ∞, respectively.  相似文献   

11.
The in vivo and in vitro effects of Cd2+ and the CYP1A inductor β-naphthoflavone(β-NF) on the hepatic cytochrome P450 (Cyt 450) monooxygenases were studied in silver carp (Hypophthalmichtys molitrix V.), wels (Silurus glanis L.), and carp (Cyprinus carpio). In vivo treatment of carp with a high dose of Cd2+ (10 mg kg−1, for 3 days) caused a strong inhibition of 7-ethoxyresorufin-O-deethylase (EROD) and a lower inhibition of 7-ethoxycoumarin-O-deethylase (ECOD) activity. The low-dose cadmium treatment (2 mg kg−1 Cd2+, for 6+3 days) resulted in 4-fold increase in EROD and a 3-fold increase in ECOD activity. The combined treatment with Cd2+ and β-NF in both cases led to a loss of EROD inducibility. The silver carp and wels were treated with 10 mg L−1 Cd2+ for 72 h in water. The Cyt P450 content in the wels liver microsomes was increased significantly after treatment for 48 h, whereas there was only a slight, not significant increase in Cyt P450 content in the silver carp microsomes. While the Cd2+ treatment resulted in inhibition of the CYP1A isoenzymes (EROD and ECOD), the APND (aminopyrene-N-demethylase, CYP2B or CYP3A isoenzyme) activity was increased 3- to 4-fold in both fish species. In vitro experiments of the effect of Cd2+ led to a concentration-dependent inhibition in all three investigated fish species. The ECOD isoenzyme of silver carp was the most sensitive to Cd2+. The lowest concentration of Cd2+ resulted in 50% inhibition. The APND isoenzyme was similarly sensitive to Cd2+ in all three investigated fish species. The most sensitive species was the wels, and the least sensitive were the carp isoenzyme. FTIR spectroscopy confirmed that cadmium caused damage to the protein structure. These results support the enzyme activity measurements measured in vivo and in vitro.  相似文献   

12.
Summary. Membrane-bound ATPases, such as Na,K-ATPase and nucleotide triphospho-diphosphohydrolase (NTPDase), being one of the first targets of a toxic action are generally considered as good markers for estimating toxicity. A bioluminescence assay was applied for fast and sensitive evaluation of heavy metals effect on the rat brain synaptosomal membrane ATPase activity. The assay consists of ATP-consuming reaction catalyzed by synaptic plasma membrane ATPases coupled to the luminescent firefly luciferase reaction, which consumes residual ATP after the course of ATPase reaction. The bioluminescence ATPase assay was applied to study the effect of heavy and transitional metals (Cu2+, Pb2+, Cd2+, Hg2+) on rat brain ATPase activity after assay optimization. All metals applied inhibited synaptic membrane ATPase activity in a concentration dependent manner. The IC 50 values (Hg2+ < Cu2+ < Cd2+ < Pb2+) obtained with the bioluminescence assay were highly correlated with those obtained by the spectrophotometric method. The fast bioluminescence ATPase assay with small sample and substrate requirements could be adjusted for high-throughput environmental and pharmacological screening.  相似文献   

13.
Employing immobilized metal‐ion affinity chromatography and magnetic separation could ideally provide a useful analytical strategy for purifying His‐tagged protein. In the current study, a facile route was designed to prepare CMPEI‐Ni2+@SiO2@Fe3O4 (CMPEI=carboxymethylated polyethyleneimine) magnetic nanoparticles composed of a strong magnetic core of Fe3O4 and a Ni2+‐immobilized carboxymethylated polyethyleneimine coated outside shell, which was formed by electrostatic interactions between polyanionic electrolyte of carboxymethylated polyethyleneimine and positively charged surface of 3‐(trimethoxysilyl)propylamin modified SiO2@Fe3O4. The resulting CMPEI‐Ni2+@SiO2@Fe3O4 composite nanoparticles displayed well‐uniform structure and high magnetic responsiveness. Hexa His‐tagged peptides and purified His‐tagged recombinant retinoid X receptor alpha were chosen as the model samples to evaluate the adsorption, capacity, and reusability of the composite nanoparticles. The results demonstrated the CMPEI‐Ni2+@SiO2@Fe3O4 nanoparticles possessed rapid adsorption, large capacity, and good recyclability. The obtained nanoparticles were further used to purify His‐tagged protein in practical environment. It was found that the nanoparticles could selectively capture His‐tagged recombinant retinoid X receptor protein from complex cell lysate. Owing to its easy synthesis, large binding capacity, and good reusability, the prepared CMPEI‐Ni2+@SiO2@Fe3O4 magnetic nanoparticles have great potential for application in biotechnological fields.  相似文献   

14.
The competitive removal of Pb2+, Cu2+, and Cd2+ ions from aqueous solutions by the copolymer of 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid (AMPS) and itaconic acid (IA), P(AMPS‐co‐IA), was investigated. Homopolymer of AMPS (PAMPS) was also used to remove these ions from their aqueous solution. In the preparation of AMPS–IA copolymer, the molar percentages of AMPS and IA were 80 and 20, respectively. In order to observe the changes in the structures of polymers due to metal adsorption, FTIR spectra by attenuated total reflectancetechnique and scanning electron microscopy (SEM) pictures of the polymers were taken both before and after adsorption experiments. Total metal ion removal capacities of PAMPS and P(AMPS‐co‐IA) were 1.685 and 1.722 mmol Me2+/gpolymer, respectively. Experimental data were evaluated to determine the kinetic characteristics of the adsorption process. Competitive adsorption of Pb2+, Cu2+, and Cd2+ ions onto both PAMPS and P(AMPS‐co‐IA) was found to fit pseudo‐second‐order type kinetics. In addition, the removal orders in the competitive adsorption of these metal ions onto PAMPS and P(AMPS‐co‐IA) were found to be Cd2+ > Pb2+ > Cu2+ and Pb2+ > Cd2+ > Cu2+, respectively. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

15.
CoNb2O6 can be prepared by reaction of stoichiometric amounts of CoO (thermical decomposition of cobaltoxalate) and Nb2O5 in argon-atmosphere up to 1,400 °C. The isolated red-brown single crystals have tetragonal symmetry (a=472.6;c=305.4 pm; space group P42/mnm-D 4h 14 ). Electron probe micro-analysis of the single crystals verifies the composition Co0.33Nb0.67O2. Co2+ and Nb5+ occupy statistically the metal positions of the rutil-type structure. The differences between Co0.5Nb0.5O2 (CoNbO4AlNbO4-type) and Co0.38Nb0.67O2 (CoNb2O6) are discussed.
  相似文献   

16.
Lithocholic acid N-(2-aminoethyl)amide (1) and deoxycholic acid N-(2-aminoethyl)amide(2) have been prepared and characterized by1H, 13C and 15N NMR. The accurate molecular masses of 1 and 2 have been determined by ESI MS. The formation of the Cd2+-complexes (1+Cd and 2+Cd) in CD3OD solution have been detected by 1H,13C, 15N and 113Cd NMR. The 13C NMR chemical shift assignments of 1 and 2 and their Cd2+-complexes are based on DEPT-135 and z-GS 1H,13C HMQC experiments as well as comparison with the assignments of the related structures. The 15N NMR chemical shiftassignments of the ligands and theirCd2+-complexes are based on z-GS1H,15N HMBC experiments. 13C NMR chemical shift differences between 1and its 1:1 Cd2+-complex based on ab initiocalculations at Hartree-Fock SCI-PCM level using3-21G(d) basis set are in agreement with theexperimental shift changes observed onCd2+-complexation.  相似文献   

17.
A simple and green analytical procedure based on chlorophyll a is presented for the determination of Hg2+ ion. Chlorophyll a was extracted and purified from the leaves of pea and is employed as a reagent for analysis of Hg2+ ion. It displays remarkable fluorescence emission at 674 nm when excited at 412 nm. The emission intensity decreased significantly on exposure to various concentrations of Hg2+ ion. This forms the basis for the determination of Hg2+ ion. The proposed method was evaluated for sensitivity and selectivity. The linear concentration range was found to be 2.0–10 μM with r2 = 0.997 and the limit of detection for Hg2+ ion was 1.3 μM. Ions including Pb2+, Cd2+, Ag+, Zn2+, Co2+, Ni2+, Cu2+, Mg2+, Mn2+, Ru3+, Er3+, K+, Na+, NH4+, Cl, NO3, CH3COO and SO42− did not interfere with the measurement of Hg2+ ion even at 500-fold excess. Since chlorophyll a is widely available in the leaves of most plants, and the extraction and purification process is simple, this technique can provide an alternative, sensitive and economical way to determine Hg2+ ion.  相似文献   

18.
The complex formation between Cu2+, Zn2+, Tl+ and Cd2+ metal cations with macrocyclic ligand, dibenzo- 18-crown-6 (DB18C6) was studied in dimethylsulfoxide (DMSO)–ethylacetate (EtOAc) binary systems at different temperatures using conductometric method. In all cases, DB18C6 forms 1:1 complexes with these metal cations. The stability constants of the complexes were obtained from fitting of molar conductivity curves using a computer program, Genplot. The non-linear behaviour which was observed for variations of log K f of the complexes versus the composition of the mixed solvent was discussed in terms of changing the chemical and physical properties of the constituent solvents when they mix with one another and, therefore, changing the solvation capacities of the metal cations, crown ether molecules and even the resulting complexes with changing the mixed solvent composition. The results show that the selectivity order of DB18C6 for the metal cations in pure ethylacetate and pure dimethylsulfoxide is: Tl+ > Cu2+ > Zn2+ > Cd2+ but the selectivity order is changed with the composition of the mixed solvents. The values of enthalpy changes (ΔH°C) for complexation reactions were obtained from the slope of the van’t Hoff plots and the changes in standard enthalpy (ΔS°C) were calculated from the relationship: ΔG°C,298.15H°C − 298.15 ΔS°C. The obtained results show that in most cases, the complexes are enthalpy stabilized, but entropy destabilized and the values of ΔH°C and ΔS°C depend strongly on the nature of the medium.  相似文献   

19.
The aim of this work is to study the effect of Sr substitution on the redox properties and catalytic activity of La2−x Sr x NiO4 (x = 0.0–1.2) for NO decomposition. Results suggest that the x = 0.6 sample shows the highest activity. The characterization (TPD, TPR, etc.) of samples indicates that the x = 0.6 sample possesses suitable abilities in both oxidation and reduction, which facilitates the proceeding of oxygen desorption and NO adsorption. At temperature below 700°C, the oxygen desorption is difficult, and is the rate-determining step of NO decomposition. With the increase of reaction temperature (T > 700°C), the oxygen desorption is favorable and, the active adsorption of NO on the active site (NO + V o + Ni2+ → NO-Ni3+) turns out to be the rate-determining step. The existence of oxygen vacancy is the prerequisite condition for NO decomposition, but its quantity does not relate much to the activity. Supported by the National Hi-Tech Research and Development Program of China (863 Program)(Grant No. 2004CB 719502) and the National Natural Science Foundation of China (Grant No. 20177022)  相似文献   

20.
Assembly of 5-sulfosalicylic acid (H3L) and d10 transition metal ions (CdII, AgI) with the neutral N-donor ligands produces five new complexes: [Cd2(HL)2(4,4′-bipy)3]n·2nH2O (1), {[Cd2(μ2-HCO2)2(4,4′-bipy)2(H2O)4][Cd(HL)2(4,4′-bipy)(H2O)2]}n (2), {[Cd(4,4′-bipy)(H2O)4][HL]·H2O}n (3), [Cd(HL)(dpp)2(H2O)]n·4nH2O (4), {[Ag(4,4′-bipy)][Hhbs]}n (5) (4,4′-bipy=4,4′-bipyridine, dpp=1,3-di(pyridin-4-yl)propane, H2hbs=4-hydroxybenzenesulfonic acid, the decarboxylation product of H3L). Complex 1 adopts a 5-connected 3D bilayer topology. Complex 2 has the herring-bone and ladder chain, which are extended to a 3D network via hydrogen bonding. In 3–4 complexes, 3 is a 3D supermolecular structure formed by polymeric chains and 2D network of HL2−, while 4 gives the double-stranded chains. In 5, ladder arrays are stacked with the 2D networks of Hhbs anions in an –ABAB– sequence. Complexes 1–4 display green luminescences in solid state at room temperature, while emission spectra of 3 and 4 show obvious blue-shifts at low temperature.  相似文献   

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