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61.
Ghanshyam S. Chauhan Kalpana Chauhan Sandeep Chauhan Sunil Kumar Anita Kumari 《Carbohydrate polymers》2007,70(4):415-421
Pine needles and their carboxymethyl forms were functionalized by network formation with 2-acrylamido-2-methylpropanesulphonic acid (AAmPSA) in the presence of N,N-methylene bisacrylamide. N-Tetramethylethylene diamine and ammonium persulfate were used as accelerator-initiator systems to prepare these hydrogels. The hydrogels were characterized by FTIR, SEM, and nitrogen analysis and for water uptake capacities before and after metal ion sorption with a view to evaluating their use in the removal of toxic ionic species from waste water. A detailed study of Cr6+ adsorption was carried out as a function of time, temperature, pH, and ionic strength. The thermodynamic parameters of adsorption such as ΔH0, ΔS0, and ΔG0 have been evaluated to understand the underlying mechanism of adsorption. In order to understand their reusability in possible technological applications, biodegradability of these hydrogels and their precursors was studied. 相似文献
62.
Efthimiadou EK Psomas G Sanakis Y Katsaros N Karaliota A 《Journal of inorganic biochemistry》2007,101(3):525-535
Nine new metal complexes of the quinolone antibacterial agent N-propyl-norfloxacin, pr-norfloxacin, with VO(2+), Mn(2+), Fe(3+), Co(2+), Ni(2+), Zn(2+), MoO(2)(2+), Cd(2+) and UO(2)(2+) have been prepared and characterized with physicochemical and spectroscopic techniques while molecular mechanics calculations for Fe(3+), VO(2+) and MoO(2)(2+) complexes have been performed. In all complexes, pr-norfloxacin acts as a bidentate deprotonated ligand bound to the metal through the pyridone and one carboxylate oxygen atoms. All complexes are six-coordinate with slightly distorted octahedral geometry. For the complex VO(N-propyl-norfloxacinato)(2)(H(2)O) the axial position, trans to the vanadyl oxygen, is occupied by one pyridone oxygen atom. The investigation of the interaction of the complexes with calf-thymus DNA has been performed with diverse spectroscopic techniques and has shown that the complexes can be bound to calf-thymus DNA resulting to a B-->A DNA transition. The antimicrobial activity of the complexes has been tested on three different microorganisms. The complexes show equal or decreased biological activity in comparison to the free pr-norfloxacin except UO(2)(pr-norf)(2) which shows better inhibition against S. aureus. 相似文献
63.
Cell suspension cultures of red spruce (Picea rubens Sarg.) were selected to study the effects of cadmium (Cd) and zinc (Zn) on phytochelatins (PCs) and related metabolites after
24 h exposure. The PC2 and its precursor, γ-glutamylcysteine (γ-EC) increased two to fourfold with Cd concentrations ranging from 12.5 to 200 μM
as compared to the control. However, Zn-treated cells showed a less than twofold increase in γ-EC and PC2 levels as compared to the control even at the highest concentration of 800 μM. In addition, unidentified higher chain PCs
were also found in both the Cd and Zn treated cells and they increased significantly with increasing concentrations of Cd
and Zn. The cellular ratio of PC2 : Cd or Zn content clearly indicated that Cd (with ratios ranging from 0.131 to 0.546) is a more effective inducer of PC2 synthesis/accumulation than Zn (with ratios ranging from 0.032 to 0.102) in red spruce cells. A marginal decrease in glutathione
(GSH) was observed in both Cd and Zn treated cells. However, the GSH precursor, cysteine, declined twofold with all Cd concentrations
while the decrease with Zn was 1.5–2-fold only at the higher treatment concentrations of Zn as compared to control. In addition,
changes in other free amino acids, polyamines, and inorganic ions were also studied. These results suggest that PCs and their
biosynthetic intermediates play a significant role in red spruce cells protecting against Cd and Zn toxicity. 相似文献
64.
M. A. Nogueira U. Nehls R. Hampp K. Poralla E. J. B. N. Cardoso 《Plant and Soil》2007,298(1-2):273-284
Excess manganese (Mn) in soil is toxic to crops, but in some situations arbuscular mycorrhizal fungi (AMF) alleviate the toxic
effects of Mn. Besides the increased phosphorus (P) uptake, mycorrhiza may affect the balance between Mn-reducing and Mn-oxidizing
microorganisms in the mycorrhizosphere and affect the level of extractable Mn in soil. The aim of this work was to compare
mycorrhizal and non-mycorrhizal plants that received extra P in relation to alleviation of Mn toxicity and the balance between
Mn-oxidizing and Mn-reducing bacteria in the mycorrhizosphere. A clayey soil containing 508 mg kg−1 of extractable Mn was fertilized with 30 mg kg−1 (P1) or 45 mg kg−1 (P2) of soluble P. Soybean (Glycine max L. Merrill, cv. IAC 8-2) plants at P1 level were non-inoculated (CP1) or inoculated with either Glomus etunicatum (GeP1) or G. macrocarpum (GmP1), while plants at P2 level were left non-inoculated (CP2). Plants were grown in a greenhouse and harvested after 80 days.
In the mycorrhizosphere of the GmP1 and GeP1 plants a shift from Mn-oxidizing to Mn-reducing bacteria coincided with higher
soil extractability of Mn and Fe. However, the occurrence of Mn-oxidizing/reducing bacteria in the (mycor)rhizosphere was
unrelated to Mn toxicity in plants. Using 16S rDNA sequence homologies, the Mn-reducing isolates were consistent with the
genus Streptomyces. The Mn-oxidizers were homologous with the genera Arthrobacter, Variovorax and Ralstonia. While CP1 plants showed Mn toxicity throughout the whole growth period, CP2 plants never did, in spite of having Fe and
Mn shoot concentrations as high as in CP1 plants. Mycorrhizal plants showed Mn toxicity symptoms early in the growth period
that were no longer visible in later growth stages. The shoot P concentration was almost twice as high in mycorrhizal plants
compared with CP1 and CP2 plants. The shoot Mn and Fe concentrations and contents were lower in GmP1 and GeP1 plants compared
with the CP2 treatment, even though levels of extractable metals increased in the soil when plants were mycorrhizal. This
suggests that mycorrhiza protected its host plant from excessive uptake of Mn and Fe. In addition, higher tissue P concentrations
may have facilitated internal detoxification of Mn in mycorrhizal plants. The exact mechanisms acting on alleviation of Mn
toxicity in mycorrhizal plants should be further investigated. 相似文献
65.
Hassinen VH Tervahauta AI Halimaa P Plessl M Peräniemi S Schat H Aarts MG Servomaa K Kärenlampi SO 《Planta》2007,225(4):977-989
Several populations with different metal tolerance, uptake and root-to-shoot transport are known for the metal hyperaccumulator
plant Thlaspi caerulescens. In this study, genes differentially expressed under various Zn exposures were identified from the shoots of two T. caerulescens accessions (calaminous and non-calaminous) using fluorescent differential display RT-PCR. cDNA fragments from 16 Zn-responsive
genes, including those encoding metallothionein (MT) type 2 and type 3, MRP-like transporter, pectin methylesterase (PME)
and Ole e 1-like gene as well as several unknown genes, were eventually isolated. The full-length MT2 and MT3 sequences differ from those previously isolated from other Thlaspi accessions, possibly representing new alleles or isoforms. Besides the differential expression in Zn exposures, the gene
expression was dependent on the accession. Thlaspi homologues of ClpP protease and MRP transporter were induced at high Zn concentrations. MT2 and PME were expressed at higher
levels in the calaminous accession. The MTs and MRP transporter expressed in transgenic yeasts were capable of conferring
Cu and Cd tolerance, whereas the Ole e 1-like gene enhanced toxicity to these metals. The MTs increased yeast intracellular
Cd content. As no significant differences were found between Arabidopsis and Thlaspi MTs, they apparently do not differ in their capacity to bind metals. However, the higher levels of MT2 in the calaminous
accession may contribute to the Zn-adapted phenotype. 相似文献
66.
CopA, a thermophilic ATPase from Archaeoglobus fulgidus, drives the outward movement of Cu+ across the cell membrane. Millimolar concentration of Cys dramatically increases (≅ 800%) the activity of CopA and other PIB-type ATPases (Escherichia coli ZntA and Arabidopsis thaliana HMA2). The high affinity of CopA for metal (≅ 1 μM) together with the low Cu+-Cys KD (< 10− 10M) suggested a multifaceted interaction of Cys with CopA, perhaps acting as a substitute for the Cu+ chaperone protein present in vivo. To explain the activation by the amino acid and further understand the mechanism of metal delivery to transport ATPases, Cys effects on the turnover and partial reactions of CopA were studied. 2-20 mM Cys accelerates enzyme turnover with little effect on CopA affinity for Cu+, suggesting a metal independent activation. Furthermore, Cys activates the p-nitrophenyl phosphatase activity of CopA, even though this activity is metal independent. Cys accelerates enzyme phosphorylation and the forward dephosphorylation rates yielding higher steady state phosphoenzyme levels. The faster dephosphorylation would explain the higher enzyme turnover in the presence of Cys. The amino acid has no significant effect on low affinity ATP Km suggesting no changes in the E1 ↔ E2 equilibrium. Characterization of Cu+ transport into sealed vesicles indicates that Cys acts on the cytoplasmic side of the enzyme. However, the Cys activation of truncated CopA lacking the N-terminal metal binding domain (N-MBD) indicates that activation by Cys is independent of the regulatory N-MBD. These results suggest that Cys is a non-essential activator of CopA, interacting with the cytoplasmic side of the enzyme while this is in an E1 form. Interestingly, these effects also point out that Cu+ can reach the cytoplasmic opening of the access path into the transmembrane transport sites either as a free metal or a Cu+-Cys complex. 相似文献
67.
Banci L Bertini I Chasapis CT Rosato A Tenori L 《Biochemical and biophysical research communications》2007,364(3):645-649
Yeast Ccc2 is a P-type ATPase responsible for transport of copper(I) from the cytosol to the trans-Golgi network. It possesses a soluble cytosolic N-terminal region containing two copper(I)-binding domains. Homologous eukaryotic copper-transporting ATPases have from one to six domains. We have expressed a fragment encompassing residues 1-150 of Ccc2, which corresponds to the two domains, and found that the second domain was substantially less structured than the first. The first domain could bind copper(I) and interact with the partner protein Atx1 at variance with the second. Similar results are found in ATPases from other organisms and may represent a general feature, whose biochemical implications are not yet fully appreciated. 相似文献
68.
Christophe Faulmann Stéphane Dorbes Kane Jacob Gábor Molnár José Antonio Real 《Inorganica chimica acta》2007,360(13):3870-3878
A new compound of formula [Fe(qsal)2][Ni(dmit)2] (1) has been synthesised, structurally and magnetically characterised (qsalH = N-(8-quinolyl)salicylaldimine, dmit2− = 1,3-dithiol-2-thione-4,5-dithiolato). Its structural features and its magnetic behaviour were compared with those of [Fe(qsal)2]-based complexes, and more particularly [Fe(qsal)2][Ni(dmit)2] · 2CH3CN. 相似文献
69.
Elisabete Oliveira Laura Valencia Emilia Bértolo Carlos Lodeiro 《Inorganica chimica acta》2007,360(8):2734-2743
A new scorpionate system (L) containing an emissive anthracene pendant arm, derived of O1,O7-bis(2-formylphenyl)-1,4,7-trioxaheptane and tren, has been synthesized and characterized. The sensing capability of L towards a range of metal ions has been studied. Protonation and complexation studies, using UV-Vis and fluorescent emission measurements, have been performed with alkaline and alkaline earth metal ions (M = Na(I), K(I), Li(I), Ca(II), Mg(II)), as well as transition and post-transition metal ions (M = Cr(III), Cu(II) and Zn(II), Cd(II), Hg(II) and Al(III)). An increase in the fluorescence emission (CHEF effect) was observed in methanol and in methanol/water mixtures in the presence of Cd(II) (5.0-fold), Zn(II) (4.5-fold), Cr(III) (2.0-fold) and Al(III) (1.8-fold); these results suggest a notable sensing ability of this new N3O4 ligand for these metals; these experiments were also performed in the presence of large amounts of alkaline and alkaline earth metal ions. 相似文献
70.
Sehye Kim 《Inorganica chimica acta》2007,360(6):1870-1874
A new organic-inorganic hybrid solid with 3-D framework, [Mn(DMF)3]2[Re6Se8(CN)6] (1), has been synthesized and transformed to [H][Mn(salen)]3[Re6Se8(CN)6] (2) by a ligand exchange. Hexarhenium chalcocyanide clusters are closest packed in cubic symmetry for 1 and rhombohedral symmetry for 2. The manganese complexes in the interstitial sites are three-coordinated to the rhenium cluster in 1 and two-coordinated in 2. 相似文献