共查询到20条相似文献,搜索用时 15 毫秒
1.
A mutiphase model of metal ion speciation in human interstitial fluid was constructed and the effect of Pr(III) on Ca(II)
speciation was studied. Results show that Ca(II) mainly distributes in free Ca2+, [Ca(HCO3)], and [Ca(Lac)]. Because of the competition of Pr(III) for ligands with Ca(II), with the total concentration of Pr(III)
rising, the percentages of free Ca2+, [Ca(Lac)] and [Ca(His)(Thr)H3], gradually increase and the percentages of CaHPO4(aq) and [Ca(Cit)(His)H2] gradually decrease. However, the percentages of [Ca(HCO3)] and CaCO3(aq) first increase, and then begin to decrease when the total concentration of Pr(III) exceeds 6.070×10−4
M. 相似文献
2.
The speciation and distribution of Zn(II) and the effect of Gd(III) on Zn(II) speciation in human blood plasma were studied
by computer simulation. The results show that, in normal blood plasma, the most predominant species of Zn(II) are [Zn(HSA)]
(58.2%), [Zn(IgG)](20.1%), [Zn(Tf)] (10.4%), ternary complexes of [Zn(Cit)(Cys)] (6.6%) and of [Zn(Cys)(His)H] (1.6%), and
the binary complex of [Zn(Cys)2H] (1.2%). When zinc is deficient, the distribution of Zn(II) species is similar to that in normal blood plasma. Then, the
distribution changes with increasing zinc(II) total concentration. Overloading Zn(II) is initially mainly bound to human serum
albumin (HSA). As the available amount of HSA is exceeded, phosphate metal and carbonate metal species are established. Gd(III)
entering human blood plasma predominantly competes for phosphate and carbonate to form precipitate species. However, Zn(II)
complexes with phosphate and carbonate are negligible in normal blood plasma, so Gd(III) only have a little effect on zinc(II)
species in human blood plasma at a concentration above 1.0×10−4
M. 相似文献
3.
A multiphase model of metal ion species in human interstitial fluid was constructed under physiological conditions. The effect
of Pr(III) on Zn(II) species was studied. At the normal conditions, Zn(II) species mainly distribute in [Zn(HSA)], [Zn(IgG)],
and [Zn(Cys)2H]+. With the Pr(III) level increased, the apparent competition of Pr(III) for ligands lead to the redistribution of Zn(II) species. 相似文献
4.
Triclinic structural and magnetic properties of praseodymium(III) picrate triethylene glycol complex
Eny Kusrini 《Inorganica chimica acta》2010,363(11):2533-2538
A study on the structure and magnetic properties of [Pr(NO3)(Pic)(H2O)2(EO3)](Pic) complex, where EO3 = triethylene glycol and Pic = picrate anion was conducted and characterized by single crystal X-ray structure analysis. Magnetic susceptibility (χM) was carried out from 2 to 300 K under both field-cooled (FC) and zero-field-cooled (ZFC) measurements with an applied magnetic field of 2000 Oe. The complex is crystallized in triclinic with space group . The coordination geometry around the Pr(III) ion was a tetradecahedron with a ten-coordination number. In the crystal, the molecular structure was stabilized by moderate and weak hydrogen bonding interactions between the cation [Pr(NO3)(Pic)(H2O)2(EO3)]+ moiety and [Pic]− as counter-anion that led to the formation of a one-dimensional network. The temperature dependence of the magnetic susceptibility of [Pr(NO3)(Pic)(H2O)2(EO3)](Pic) shows the presence of weak antiferromagnetic interactions between the Pr(III) centers. The magnetic susceptibility for complex also obeys the Curie-Weiss law and is effective at high temperatures. Some factors that influence the photoluminescence intensity were also reported. 相似文献
5.
Ritam Mukherjee 《Inorganica chimica acta》2007,360(11):3633-3636
Titanium(II) solutions, prepared by dissolving titanium wire in triflic acid + HF, contain equimolar quantities of Ti(IV). Treatment of such solutions with excess Fe(III) or Ru(III) complexes yield Ti(IV), but reactions with Ti(II) in excess give Ti(III). Oxidations by (NH3)5Ru(III) complexes, but not by Fe(III) species, are catalyzed by titanium(IV) and by fluoride. Stoichiometry is unchanged. The observed rate law for the Ru(III)-Ti(II)-Ti(IV) reactions in fluoride media points to competing reaction paths differing by a single F−, with both routes involving a Ti(II)-Ti(IV) complex which is activated by deprotonation. It is suggested that coordination of Ti(IV) to TiII(aq) minimizes the mismatch of Jahn-Teller distortions which would be expected to lower the Ti(II,III) self-exchange rate. 相似文献
6.
The speciation and distribution of Gd(III) in human interstitial fluid was studied by computer simulation. The results show that at the background concentration, all the Gd(III) species are soluble and no precipitates appear. However as the total concentration of Gd(III) rises above 2.610 × 10–9 mol/l,the insoluble species become predominant. GdPO4 is formed first as a precipitate and then Gd2(CO3)3. Among soluble species, free Gd(III), [Gd(HSA)], [Gd(Ox)] and the ternary complexes of Gd(III) with citrate as the primary ligand are main species when the total concentration of Gd(III) is below 2.074 × 10–2 mol/l. With the total concentration of Gd(III) further rising, [Gd3(OH)4] begins to appear and gradually becomes a predominant species. 相似文献
7.
Nourhan S. Sultan Heba K. A. Elhakim Azza A. Shoukry Fatma B. Rashidi 《化学与生物多样性》2023,20(7):e202300450
Two novel copper (II) complexes [Cu(TFP)(Gly)Cl] ⋅ 2H2O complex ( 1 ) and [Cu(TFP)(His)Cl] ⋅ 2H2O complex ( 2 ) are synthesized, where TFP stands for trifluropromazine, Gly. represents glycine, and His. is histidine. Chemical composition, IR, mass spectra, and magnetic susceptibility tests are performed. Complex binding with macromolecules was investigated using UV-vis, viscosity, gel electrophoresis, and fluorescence quenching. Fluorescence spectroscopy revealed that each complex could replace ethidium bromide (EB). These complexes exhibit grooved, non-covalent, and electrostatic interactions with CT-DNA. Spectroscopy analysis of the BSA interaction showed that complexes bind to protein (Kb values for ( 1 ) is 5.89×103 M−1 and for ( 2 ) is 9.08×103 M−1) more strongly than CT-DNA (Kb values for ( 1 ) is 5.43×103 M−1 and for ( 2 ) is 7.17×103 M−1). Molecular docking analysis and spectral absorption measurements showed high agreement. Antimicrobial, antioxidant, and anti-inflammatory properties were tested in vitro. The druggability of complex ( 2 ) should be tested in vivo as it is more biologically active. 相似文献
8.
《Inorganica chimica acta》1988,149(1):139-145
The stoichiometry and kinetics of the reaction between [Cu(dien)(OH)]+ and [Fe(CN)6]3− in aqueous alkaline medium are described. The rate equation − (d[Fe(III)]/dt = {k1[OH−]2[[Cu(dien)(OH)]+] + k2[OH−] × [[Cu(dien)(OH)]+]2}([Fe(III)]/[Fe(II)]) (Fe(III) = [Fe(CN)6]3−; Fe(II) = [Fe(CN)6]4−, the 4:4:1 OH−/Fe(III)/[Cu(dien)(OH)]+ stoichiometric ratio and the nature of the ultimate products identified in the reaction solution suggest the fast formation of a doubly deprotonated Cu(III)-diamido complex which slowly undergoes an internal redox process where the ligand is oxidised to the Schiff base H2NCH2CH2NCHCHNH.The [[Cu(dien)(OH)]+]2 term in the rate equation is explained with the formation of a transient μ-hydroxo mixed-valence Cu dimer. A two-electron internal reduction of the Cu(III) complex yielding a Cu(I) intermediate is suggested to account for the presence of monovalent copper in a precipitate which forms at relatively high reactant concentrations and in the absence of dioxygen. 相似文献
9.
Angiotensin II (ANG II) stimulates renal tubular reabsorption of NaCl by targeting Na+/H+ exchanger NHE3. We have shown previously that inositol 1,4,5-triphosphate receptor-binding protein released with inositol 1,4,5-triphosphate (IRBIT) plays a critical role in stimulation of NHE3 in response to elevated intracellular Ca2+ concentration ([Ca2+]i). In this study, we investigated the role of IRBIT in mediating NHE3 activation by ANG II. IRBIT is abundantly expressed in the proximal tubules where NHE3 is located. ANG II at physiological concentrations stimulates NHE3 transport activity in a model proximal tubule cell line. ANG II-induced activation of NHE3 was abrogated by knockdown of IRBIT, whereas overexpression of IRBIT enhanced the effect of ANG II on NHE3. ANG II transiently increased binding of IRBIT to NHE3 at 5 min but became dissociated by 45 min. In comparison, it took at least 15 min of ANG II treatment for an increase in NHE3 activity and NHE3 surface expression. The stimulation of NHE3 by ANG II was dependent on changes in [Ca2+]i and Ca2+/calmodulin-dependent protein kinases II. Inhibition of CaMKII completely blocked the ANG II-induced binding of IRBIT to NHE3 and the increase in NHE3 surface abundance. Several serine residues of IRBIT are thought to be important for IRBIT binding. Mutations of Ser-68, Ser-71, and Ser-74 of IRBIT decreased binding of IRBIT to NHE3 and its effect on NHE3 activity. In conclusion, our current findings demonstrate that IRBIT is critically involved in mediating activation of NHE3 by ANG II via a Ca2+/calmodulin-dependent protein kinases II-dependent pathway. 相似文献
10.
Classic phenylketonuria (PKU) is characterized by brain lesions. However, its underlying neurotoxic mechanisms remain unknown.
Based on our previous studies, we hypothesized that calcium might participate in PKU-associated neuropathy. In cultured cortical
neurons, cytoplasmic free calcium concentration ([Ca2+]i) decreased dramatically when treatment with phenylalanine (Phe) and phenyllactic acid, while phenylacetic acid treatment
immediately increased [Ca2+]i, which began to decrease after 3 min. Moreover, [Ca2+]i decreased dramatically after Phe treatment in the presence of EGTA suggesting that Phe might increase [Ca2+]i efflux. Phe-induced [Ca2+]i decrease was strongly inhibited by vanadate, a non-specific plasma membrane Ca2+-ATPase (PMCA) antagonist, suggesting that Phe might increase [Ca2+]i efflux throught modulating PMCA. These findings were further supported by the facts that Phe could increase membrance 45Ca-uptake capability and PMCA activity. In contrast, treatment of KBR7943 or thapsigargin, antagonists to Na/Ca Exchanger
(NCX) and Sarco/Endoplasmic reticulum Ca2+-ATPase (SERCA), respectively, did not elicit any changes in [Ca2+]i. Specific siRNA against PMCA had an effect similar to vanadate. Since the brain injury induced by phenylalaninemia was thought
to be a chronic process, we cultured cortical neurons in the presence of Phe for 2 weeks and measured [Ca2+]i, PMCA activity and 45Ca-uptake capability at days 3, 7, 9 and 14, respectively. PMCA activity and 45Ca-uptake capability decreased from day 9, at the same time [Ca2+]i increase was observed. In conclusion, PMCA participate in regulating Phe-induced initial rapid decrease in [Ca2+]i and subsequent long-term increase in [Ca2+]i. 相似文献
11.
Aktham N. Jasim Azhar Kamel Nagham S. Al-Awadi Hussein Fares Abd-Alrazack 《Luminescence》2023,38(3):360-368
A simple, rapid, sensitive and inexpensive approach is described in this work based on a combination of solid-phase extraction of 8-hydroxyquinoline (8HQ), for speciation and preconcentration of Cr(III) and Cr(VI) in river water, and the direct determination of these species using a flow injection system with chemiluminescence detection (FI–CL) and a 4-diethylamino phenyl hydrazine (DEAPH)–hydrogen peroxide system. At different pH, the two forms of chromium [Cr(III) and Cr(VI)] have different exchange capacities for 8HQ, therefore two columns were constructed; the pH of column 1 was adjusted to pH 3 for retaining Cr(III) and column 2 was adjusted to pH 1 for retaining of Cr(VI). The sorbed Cr(III) and Cr(VI) species were eluted from columns using 3.0 ml of 0.1 N of HCl and 3.0 ml of 0.1 N of NaOH, respectively. The flow injection–chemiluminescence (FI–CL) method is based on light emitted due to the oxidation of DEAPH by the H2O2 in the presence of Cr(III), which catalyzes the reaction. The flow cell is a transparent coiled tube made from glass (2.0 × 4.0, inner and outer diameter) and located close to the photodetector. The flow parameters: flow rate, sample volume, flow cell length, and distance to the CL detector were studied and optimized. Under optimum flow conditions, the Cr(III) concentration can be determined over the range 5–350 μg L−1 with a limit of detection of 1.2 μg L−1, as the Cr(III) concentration is proportional to the intensity of the CL signal. The relative standard deviations (%) for 10 and 50 μg L−1 Cr(III) were 1.2% and 3.2%, respectively. The effects of Al(III), Cd(II), Zn(II), Hg(II), Pb(II), Co(II), Cu(II), Ni(II), Mn(II), Ca(II), and Fe(III) were investigated. The proposed method is highly selective and sensitive, enabling a rapid determination of the Cr(III) amount in the presence of other interfering metals. Finally, the FI–CL method was examined in five river water samples with excellent recoveries. 相似文献
12.
Pedro Gili Alfredo MederosEduardo Medina de la Rosa Alfonso Muñoz 《Inorganica chimica acta》2002,331(1):16-24
A computational study of chromium(VI) and (V) peroxides, which exhibit important genotoxic and mutagenic activity, is reported. Energies and equilibrium geometries for [CrVI(O)(O2)2(OH)]−, [CrVI(O)(O2)2(OH2)], [CrVI(O)(O2)2(py)], [CrVI(OH)(O2)2(OH2)]+, [CrV(O)(O2)2(OH2)]− and species were calculated using molecular mechanics calculations (MMFF94 and MM+), quantum calculations with semi-empirical methods (RHF and UHF/PM3) and density functional theory (pBP86/DN* or pBP/DN* and B3LYP/6-31G(d). Equilibrium geometries for the compounds [CrV(O2)3(OH)]2− and [CrV(O2)4]3− were determined by molecular mechanics. Vibrational frequencies, standard thermodynamic quantities and electronic spectra were calculated using B3LYP/6-31G(d). The structural relationship between all these species and an explanation of the formation of peroxo species in the acid-basic pH range are given. An experimental study of peroxo species in basic medium was also performed (synthesis, X-ray powder diffraction patterns and infrared spectra of the peroxo complexes isolated) but did not confirm the existence of a tri-peroxo complex in the solid phase. 相似文献
13.
The particulate fraction from osmotically shocked synaptosomes (‘synaptosomal membranes’) sequesters Ca when incubated with ATP-containing solutions. This net accumulation of Ca can reduce the free [Ca2+] of the bathing medium to sub-micromolar levels (measured with arsenazo III). Two distinct types of Ca sequestration site are responsible for the Ca2+ buffering. One site, presumed to be smooth endoplasmic reticulum, operates at low [Ca2+] (less than 1 μM), and has a relatively small capacity. Ca sequestration at this site is prevented by the Ca2+ ionophore, A-23187, but not by mitochondrial poisons. The second (mitochondrial) site, in contrast, is blocked by the mitochondrial uncoupler, carbonyl cyanide p-trifluoromethoxyphenylhydrazone, and oligomycin. Since the intraterminal organelles can buffer [Ca2+] to about 0.3–0.5 μM, this may be an upper limit to the normal resting level of [Ca2+]i in nerve terminals. In the steady state, total cell Ca and [Ca2+]i will be governed principally by Ca transport mechanisms in the plasmalemma; the intracellular organelle transport systems then operate in equilibrium with this [Ca2+]. During activity, however, Ca rapidly enters the terminals and [Ca2+]i rises. The intracellular buffering mechanisms then come into play and help to return [Ca2+]i toward the resting level; the non-mitochondrial Ca sequestration mechanism probably plays the major role in this Ca buffering. 相似文献
14.
The HCO3− anion activates sperm motility, an important early step in capacitation, by increasing flagellar beat frequency through a pathway that requires the atypical adenylyl cyclase SACY and the sperm-specific Cα2 catalytic subunit of PKA. Here we show that the accelerating action of HCO3− also requires the continued presence of external Ca2+ (EC50 ∼ 0.5 mM), and find that Ca2+ can be replaced by Sr2+ but not by Mn2+. Ca2+ is required for HCO3− to elevate cAMP, but not for cAMP-AM to increase beat frequency, indicating that external Ca2+ acts before rather than after stimulation of SACY by HCO3−. With external Ca2+ present, HCO3− does not alter cytosolic or near-membrane [Ca2+]. Removal of external Ca2+ initiates a slow decline in intracellular [Ca2+] and rapid block of the HCO3−-evoked acceleration that is not relieved upon increasing internal [Ca2+] by rapid photolysis of caged Ca2+. We also find that the rapid (t1/2 ∼ 10 s) accelerating action of HCO3− is slowed more than three-fold by the carbonic anhydrase inhibitor acetazolamide. It is unaltered by the broad spectrum anion transport inhibitor SITS, and is not accompanied by detectable changes in intracellular pH. We propose that external Ca2+ binds an unidentified extracellular protein that is required for HCO3− to engage cAMP-mediated activation of motility. 相似文献
15.
S S Tong Y Hirokata M A Trush E G Mimnaugh E Ginsburg M C Lowe T E Gram 《Biochemical and biophysical research communications》1981,100(3):944-950
The photosystem II electron acceptor 3,6-dichloro-2,5-dimethoxy-p-benzoquinone [DCDMQ] is suggested to replace the second quinone-type two electron acceptor B (or R); the DCDMQ Hill reaction is sensitive to 3-(3,4-dichlorophenyl)-1,1-dimethylurea, but is insensitive to dry heptane extraction of thylakoids and other photosystem II inhibitors. Addition of HCO3? to CO2-depleted thylakoids in silicomolybdate, DCDMQ, diaminodurene and ferricyanide Hill reactions brought about 1,3,10 and 10 fold increase in the electron transport rates; these data confirm that HCO3? affects both Q? to B and B2? to PQ reactions. 相似文献
16.
Manolis Matzapetakis Debdip Ghosh Tsu-Chien Weng James E. Penner-Hahn Vincent L. Pecoraro 《Journal of biological inorganic chemistry》2006,11(7):876-890
Herein, we evaluate the binding of Pb(II) and Bi(III) to cysteine-substituted versions of the TRI peptides [AcG-(LKALEEK)4G-NH2] which have previously been shown to bind Hg(II) and Cd(II) in unusual geometries as compared with small-molecule thiol ligands in aqueous solutions. Studies of Pb(II) and Bi(III) with the peptides give rise to complexes consistent with the metal ions bound to three sulfur atoms with M–S distances of 2.63 and 2.54 Å, respectively. Competition experiments between the metal ions Pb(II), Cd(II), Hg(II) and Bi(III) for the peptides show that Hg(II) has the highest affinity, owing to the initial formation of the extremely strong HgS2 bond. Cd(II) and Pb(II) have comparable binding affinities at pH > 8, while Bi(III) displays the weakest affinity, following the model, M(II) + (TRI LXC)3 3? → M(II)(TRI LXC)3 ?. While the relevant equilibria for Hg(II) binding to the TRI peptides corresponds to a strong first step forming Hg(TRI LXC)2(HTRI LXC), followed by a single deprotonation to give Hg(TRI LXC)3 ?, the binding of Cd(II) and Pb(II) is consistent with initial formation of M(II)(TRI LXC)(HTRI LXC)2 + at pH < 5 followed by a two-proton dissociation step (pK a2) yielding M(II)(TRI LXC)3 ?. Pb(II)(TRI LXC)(HTRI LXC)2 + converts to Pb(II)(TRI LXC)3 ? at slightly lower pH values than the corresponding Cd(II)–peptide complexes. In addition, Pb(II) displays a lower pK a of binding to the “d”-substituted peptide, (TRI L12C, pK a2 = 12.0) compared with the “a”-substituted peptide, (TRI L16C, pK a2 = 12.6), the reverse of the order seen for Hg(II) and Cd(II). Pb(II) also showed a stronger binding affinity for TRI L12C (K bind = 3.2 × 107 M?1) compared with that with TRI L16C (K bind = 1.2 × 107 M?1) at pH > 8. 相似文献
17.
Reactions of Ca(NO3)2·4H2O and diethylmalonic acid (Et2malH2, its anions represent functional side-chain analogs of γ-carboxyglutamic acid residues which are implicated as essential Ca2+-binding ligands in a variety of proteins) in aqueous media have afforded compounds [Ca(Et2malH)2(H2O)3]n (1) and [Ca(Et2mal)(H2O)]n (2) at pH 4 and 8, respectively. The structure of 1 was determined by single-crystal, X-ray crystallography, which revealed an 1D coordination polymer. The diethylmalonate ligands exist in their monoanionic form and present two different coordination modes. The CaII ion is 7-coordinate with a pentagonal bipyramidal geometry. IR data are discussed in terms of the known (1) and proposed (2) structures of the complexes. The role of the carboxylate binding modes in determining the affinity of Ca2+ for the various metal binding sites in proteins containing the γ-carboxyglutamate residue is discussed in the light of our and previous results. 相似文献
18.
Some zinc (II) complexes having formula [Zn(PziPr2H)(μ-PziPr2)(RCOO)]2 [(PziPr2H = 3,5-diisopropylpyrazole, RCOO− = carboxylate ligands with R is CH3 for 1, CF3 for 2, CH3(CH2)2 for 3, CH3(CH2)4 for 4 and CH3(CH2)5 for 5] were prepared and structurally characterized by different techniques including single crystal X-ray. The X-ray studies suggested that all these complexes are centrosymmetric dinuclear with tetrahedral geometry around each zinc center. The pyrazole ligand is coordinated in both terminal as well as a bridging fashion whereas the carboxylates behave as monodentate ligand. All the complexes show hydrogen bonding between hydrogen atom of pyrazole (N-H of terminal pyrazole) and nonbonded oxygen atom of carboxylate. Out of these complexes only 5 [Zn(PziPr2H)(μ-PziPr2)(CH3(CH2)5COO)]2 exhibited emission at room temperature. 相似文献
19.
Copper(II) cations coordinated with PMDTA (pentamethyldiethylenetriamine) and TMEDA (tetramethylethylenediamine) possess a high synthetic potential. The synthesis of these cations was carried out by metathesis reactions with silver salts. The cationic copper(II) complexes, [Cu(PMDTA)(Me2CO)Cl]+, [Cu(PMDTA)(H2O)Cl]+, [Cu(PMDTA)(DMF)]+, [Cu(PMDTA)Cl]+, [Cu(PMDTA)OAc]+, [Cu(PMDTA)(MeCN)2]2+, [Cu2(TMEDA)2Cl3]+ and [Cu(TMEDA)(MeCN)3]2+ were synthesised as PF6 salts, crystallised and characterised by single-crystal X-ray diffraction. 相似文献
20.
《Inorganica chimica acta》1988,145(2):299-302
The reactions of dirhodium(II) aquo cation {Rh2(aq)4+} with dioxygen were examined. It has been found that the nature of the oxidation product depends upon the concentration of dioxygen in the solution. The dimeric or polymeric Rh(III)(aq) cationic species with a charge of greater than +3 is formed when air oxygen slowly diffuses into a solution containing Rh2(aq)4+. The paramagnetic cation of proposed formula [(H2O)4Rh(O2−)(OH)2Rh(H2O)4]3+ is formed when molecular oxygen is bubbled through a 2–3 M HClO4 solution of Rh2(aq)4+. This species has been isolated and characterized in solution. 相似文献