Showing papers on "Vanadate published in 2004"
TL;DR: Results suggest that HMA2 is responsible for Zn2+ efflux from the cells and therefore is required for maintaining low cytoplasmic Zn 2+ levels and normal Zn1+ homeostasis.
Abstract: PIB-type ATPases transport heavy metal ions (Cu+, Cu2+, Zn2+, Cd2+, Co2+, etc.) across biological membranes. Several members of this subfamily are present in plants. Higher plants are the only eukaryotes where putative Zn(2+)-ATPases have been identified. We have cloned HMA2, a PIB-ATPase present in Arabidopsis (Arabidopsis thaliana), and functionally characterized this enzyme after heterologous expression in yeast (Saccharomyces cerevisiae). HMA2 is a Zn(2+)-dependent ATPase that is also activated by Cd2+ and, to a lesser extent, by other divalent heavy metals (Pb2+, Ni2+, Cu2+, and Co2+). The enzyme forms an acid-stable phosphorylated intermediate and is inhibited by vanadate. HMA2 interacts with Zn2+ and Cd2+ with high affinity (Zn2+ K(1/2) = 0.11 +/- 0.03 microm and Cd2+ K(1/2) = 0.031 +/- 0.007 microm). However, its activity is dependent on millimolar concentrations of Cys in the assay media. Zn2+ transport determinations indicate that the enzyme drives the outward transport of metals from the cell cytoplasm. Analysis of HMA2 mRNA suggests that the enzyme is present in all plant organs and transcript levels do not change in plants exposed to various metals. Removal of HMA2 full-length transcript results in Zn2+ accumulation in plant tissues. hma2 mutant plants also accumulate Cd2+ when exposed to this metal. These results suggest that HMA2 is responsible for Zn2+ efflux from the cells and therefore is required for maintaining low cytoplasmic Zn2+ levels and normal Zn2+ homeostasis.
222 citations
TL;DR: It is proposed that an opportunity exists for vanadate to become a more commonly utilized component of the macromolecular crystallographer's toolbox for visualization of transition state analogs.
128 citations
TL;DR: In this article, the formation, chemistry, morphology, and corrosion protection of a vanadate conversion coating is described, which is a new type of inorganic conversion coating, referred to as a vanadiate conversion.
Abstract: In this paper, the formation, chemistry, morphology, and corrosion protection of a new type of inorganic conversion coating is described. This coating, referred to as a vanadate conversion...
116 citations
TL;DR: The three vanadium compounds exhibited different permeability due to different diffusion process and cellular uptake, and the toxicity of vanadium complexes on Caco-2 monolayer involved F-actin-related change of tight junction and impairment of microvilli.
Abstract: Purpose. The aim of this study was to investigate the mechanism of permeation and cytotoxicity of vanadium compounds, [VO(acac)2], [VO(ma)2], and vanadate.
92 citations
TL;DR: It is suggested that the decreased apparent K+ affinity is the basis for a reduced rate of extracellular K+ removal, which delays the recovery phase of nerve impulse transmission in the central nervous system and, thereby, the clinical picture of migraine with aura.
77 citations
TL;DR: Comparisons of the partial reactions of mutant E183A and wild-type Ca(2+)-ATPase indicate that E183 is critical for the phosphatase function of E(2) and E( 2)P, possibly interacting with the phosphoryl group or attacking water in the transition state complex, but is of little functional importance in E(1) and N.
Abstract: The recently determined crystal structures of the sarcoplasmic reticulum Ca2+-ATPase show that in the E1Ca2 form, domain A is almost isolated from the other cytoplasmic domains, P and N, whereas in E2, domain A has approached domains P and N, with E183 of the highly conserved P-type ATPase signature sequence TGES in domain A now being close to the phosphorylated aspartate in domain P, thus raising the question whether E183 acquires a catalytic role in E2 and E2P conformations. This study compares the partial reactions of mutant E183A and wild-type Ca2+-ATPase, using transient and steady-state kinetic measurements. It is demonstrated that dephosphorylation of the E2P phosphoenzyme intermediate, as well as reverse phosphorylation of E2 with Pi, is severely inhibited in the mutant. Furthermore, the apparent affinity of E2 for the phosphoryl transition state analog vanadate is reduced by three orders of magnitude, consistent with a destabilization of the transition state complex, and the mutant displays reduced apparent affinity for Pi in the E2 form. The E1Ca2 conformation, on the other hand, shows normal phosphorylation with ATP and normal Ca2+ binding properties, and the rates of the conformational transitions E1PCa2 → E2P and E2 → E1Ca2 are only 2- to 3-fold reduced, relative to wild type. These results, which likely can be generalized to other P-type ATPases, indicate that E183 is critical for the phosphatase function of E2 and E2P, possibly interacting with the phosphoryl group or attacking water in the transition state complex, but is of little functional importance in E1 and E1P.
76 citations
TL;DR: A series of mono-and oligonuclear vanadium and vanadium(IV) complexes containing various chelating N,O-, N3-, and O2ligands have been prepared as discussed by the authors.
69 citations
TL;DR: In this paper, the photoluminescence properties of nanocrystalline YVO4: Tm phosphor synthesized by the polymerizable complex method based on the Pechini-type reaction were reported.
64 citations
TL;DR: Lower doses of vanadate could be used in combination with Trigonella foenum graecum seed powder to effectively counter diabetic alterations without any toxic side effects.
55 citations
TL;DR: It is concluded that vanadate causes NO release via a mechanism that involves Akt-induced eNOS phosphorylation and increased binding of the activator protein hsp90 to eN OS.
Abstract: We investigated the molecular mechanisms of sodium vanadate (vanadate)-induced nitric oxide (NO) production. Exposure of bovine lung microvascular cells (BLMVEC) to vanadate increased the release of biologically active NO in endothelium/smooth muscle cocultures, as measured by the accumulation of its surrogate marker, cGMP. This release was sensitive to NO synthase (NOS) inhibition and was greater than that observed with ionomycin. Although calcium chelators (BAPTA, EGTA) inhibited basal and ionomycin-induced NO production, they failed to inhibit vanadate-induced NO release. Moreover, in the absence of calcium/calmodulin, cell lysates from vanadate-treated cells exhibited greater NOS activity compared with control cells. Vanadate activates the phosphoinositide3-kinase (PI3-K)/Akt pathway, which is known to increase endothelial NOS (eNOS) activity by direct phosphorylation of Ser-1179. Treatment of BLMVEC with vanadate resulted in phosphorylation of both Akt and endothelial NOS. In addition, wortmannin, a PI3-K inhibitor, blocked both the vanadate-induced phosphorylation of eNOS and the increase in cGMP accumulation. Similarly, adenovirus-mediated gene transfer of an activation deficient form of Akt (AA-Akt) blocked the release of NO brought about by vanadate. To further investigate the mechanism of action of vanadate, eNOS was immunoprecipitated and its association with proteins that alter eNOS activity was tested. Immunoblots demonstrated that the eNOS-caveolin interaction remained unaffected by vanadate, whereas vanadate promoted recruitment of the 90-kDa heat shock protein (hsp90) to eNOS. We conclude that vanadate causes NO release via a mechanism that involves Akt-induced eNOS phosphorylation and increased binding of the activator protein hsp90 to eNOS.
51 citations
TL;DR: The study shows that, in the trigonal bipyramidal active site, where one axial position is occupied by a key histidine, the trans position cannot contain a terminal oxo group, and shows that the protonation state of the vanadate ion is most likely greater than previously proposed.
Abstract: Density functional theory has been used to investigate structural and electronic properties of complexes related to the resting form of the active site of vanadium haloperoxidase as a function of environment and protonation state. Results obtained by studying models of varying size and complexity highlight the influence of environment and protonation state on the structure and stability of the metal cofactor. The study shows that, in the trigonal bipyramidal active site, where one axial position is occupied by a key histidine, the trans position cannot contain a terminal oxo group. Further, a highly negatively charged vanadate unit is not stable. Protonation of at least one equatorial oxo ligand appears necessary to stabilize the metal cofactor. The study also indicates that, while at rest within the protein, the vanadate unit is most likely an anion with an axial hydroxide and an equatorial plane containing two oxos and a hydroxide. For the neutral, protonated state of the vanadate unit, there were two minima found. The first structure is characterized by an axial water with two oxo and one hydroxo group in the equatorial plane. The second structure contains an axial hydroxo group and an equatorial plane composed of one oxo and two hydroxo oxygen atoms. These two species are not significantly different in energy, indicating that either form may be important during the catalytic cycle. These data support the initial crystallographic assignment of an axially bound hydroxide, but an axial water is also a possibility. This study also shows that the protonation state of the vanadate ion is most likely greater than previously proposed.
TL;DR: The versatility of this system suggests that the formation of quaternary complexes around vanadate could be adapted to become a useful method for structure-based inhibitor design and has the potential to be generally applicable to other enzymes that perform chemistry on phosphate esters.
Abstract: Tyrosyl-DNA phosphodiesterase (Tdp1) catalyzes the hydrolysis of a phosphodiester bond between a tyrosine residue and a DNA 3' phosphate and functions as a DNA repair enzyme that cleaves stalled topoisomerase I-DNA complexes. We previously determined a procedure to crystallize a quaternary complex containing Tdp1, vanadate, a DNA oligonucleotide, and a tyrosine-containing peptide that mimics the transition state for hydrolysis of the Tdp1 substrate. Here, the ability of vanadate to accept a variety of different ligands is exploited to produce several different quaternary complexes with a variety of oligonucleotides, and peptides or a tyrosine analogue, in efforts to explore the binding properties of the Tdp1 DNA and peptide binding clefts. Eight crystal structures of Tdp1 with vanadate, oligonucleotides, and peptides or peptide analogues were determined. These structures demonstrated that Tdp1 is able to bind substituents with limited sequence variation in the polypeptide moiety and also bind oligonucleotides with sequence variation at the 3' end. Additionally, the tyrosine analogue octopamine can replace topoisomerase I derived peptides as the apical ligand to vanadate. The versatility of this system suggests that the formation of quaternary complexes around vanadate could be adapted to become a useful method for structure-based inhibitor design and has the potential to be generally applicable to other enzymes that perform chemistry on phosphate esters.
TL;DR: In this paper, a two-dimensional organic−inorganic hybrid vanadate complex [CoIII(phen)2}2V8O23] has been synthesized and characterized by elemental analyses, IR spectroscopy, XPS spectrography, TG analysis and single-crystal X-ray diffraction.
Abstract: A novel two-dimensional organic−inorganic hybrid vanadate complex [{CoIII(phen)2}2V8O23] has been hydrothermally synthesized and characterized by elemental analyses, IR spectroscopy, XPS spectroscopy, TG analysis and single-crystal X-ray diffraction. The single-crystal X-ray diffraction analysis reveals that compound 1 contains an unprecedented neutral 2D framework constructed of 4,10,12-net sheets. To the best of our knowledge, compound 1 represents the first example of 2D layered vanadium oxide complex constructed of 4,10,12-net sheets. Furthermore, the title compound consists of left-handed and right-handed helical chains, which are further interconnected to form the double-helical chains. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
TL;DR: In this article, the redox ratio (V (+IV) /V total ) was measured by wet chemical analysis, and found to be consistent with magnetic measurements on glasses, which is explained by the variation of the acid-base character of the melts.
Abstract: xV 2 O 5 -(100-x)NaPO 3 glasses were prepared with 0 ≤ x ≤ 80. The redox ratio (V (+IV) /V total ) was measured by wet chemical analysis, and found to be consistent with magnetic measurements on glasses. It decreases with increasing x values, which is explained by the variation of the acid-base character of the melts. The glass transition temperature first increases with x, then decreases for x values larger than 20%. 31 P MAS-NMR indicates that PO 4 tetrahedra are connected first to one vanadate, then to two vanadate groups. The assignment is further confirmed by double-quantum filtered 31 P MAS-NMR, and also by considering the chemical shift of crystalline references. 51 V MAS-NMR spectra show two resonances for x lower than 20%, which are assigned to tetrahedral and octahedral vanadate sites. For x values larger than 20%, only tetrahedral vanadium sites remain, then progressively change into sites similar to those in V 2 O 5 . The shift to high field of the 31 P chemical shift of PO 4 groups isolated in the vanadate network, is attributed to the evolution of the vanadium co-ordination. The non-linear evolution of the glass transition temperatures is interpreted from the structural data: the increase of Tg at low x values is due to the reticulation of the phosphate network by VO 6 groups, whereas the decrease of Tg for x larger than 20% is due to the formation of a vanadate network.
TL;DR: Calcium phosphate-vanadate apatite (CPVAP) works effectively as a catalyst for the aerobic oxidation of propargylic alcohols to the corresponding carbonyl compounds under an atmospheric pressure of molecular oxygen as discussed by the authors.
TL;DR: The interaction between the vanadate ion (VO 3 −, i.e. vanadium (V)) and the carbohydrates sucrose, glucose and fructose has been studied in aqueous solutions using measurements of diffusion coefficients, electrical conductivity, Raman and multinuclear NMR spectroscopy as discussed by the authors.
TL;DR: A constitutively active form of At-ACA8, a plasma membrane Ca2-ATPase from Arabidopsis thaliana (L.) Heynh.
Abstract: A constitutively active form of At-ACA8, a plasma membrane Ca2+-ATPase from Arabidopsis thaliana (L.) Heynh., from which the first 74 amino acids containing the calmodulin-binding domain (Δ74-At-ACA8) had been deleted, was expressed in Saccharomyces cerevisiae strain K616, which lacks the main endogenous active Ca2+ transport systems. Δ74-At-ACA8 complemented the K616 phenotype, making it able to grow in a calcium-depleted medium. Δ74-At-ACA8 protein, which co-migrated with the endoplasmic reticulum marker BiP in a sucrose-density gradient, catalyzed MgATP-dependent Ca2+ uptake and Ca2+-dependent MgATP hydrolysis, and retained the biochemical characteristics of the native plant plasma membrane Ca2+-ATPase (low specificity for nucleoside triphosphate, high sensitivity to inhibition by the fluorescein derivatives erythrosin B and eosin Y), thus confirming that it is correctly folded and functional. Substitution of the 794HE residues (numbers refer to full-length At-ACA8) following the highly conserved TGDG(TV)NDP(AS)L motif in the cytoplasmic headpiece with two lysine residues generated an hyperactive protein, with a catalytic activity 2-fold higher than that of Δ74-At-ACA8. The 794HE→KK mutant was also about 6-fold more sensitive than Δ74-At-ACA8 to inhibition by vanadate, indicating that the mutation determines an increase in the proportion of enzyme in the E2 state during the catalytic cycle.
TL;DR: The results supported the existence of a specific halogen binding site within the catalytic cleft of vanadium haloperoxidases.
Abstract: The halide specificity of vanadium-dependent bromoperoxidase (BPO) from the marine algae, Corallina pilulifera, has been changed by a single amino acid substitution. The residue R397 has been substituted by the other 19 amino acids. The mutant enzymes R397W and R397F showed significant chloroperoxidase (CPO) activity as well as BPO activity. These mutant enzymes were purified and their properties were investigated. The maximal velocities of CPO activities of the R397W and R397F enzymes were 31.2 and 39.2 units/mg, and the K(m) values for Cl(-) were 780 mM and 670 mM, respectively. Unlike the native enzyme, both mutant enzymes were inhibited by NaN(3). In the case of the R397W enzyme, the incorporation rate of vanadate into the active site was low, compared with the R397F and the wild-type enzyme. These results supported the existence of a specific halogen binding site within the catalytic cleft of vanadium haloperoxidases.
TL;DR: In this paper, the polarized Raman spectra of a series of isostructural vanadate/phosphate compounds of the form: Tb(V1−xPx)O4 with 0.75 have been investigated at room temperature.
Abstract: The polarized Raman spectra of a series of isostructural vanadate/phosphate compounds of the form: Tb(V1−xPx)O4 with 0⩽x⩽0.75 have been investigated at room temperature. While the observed Raman spectra are generally consistent with group theory predictions for a body-centered tetragonal crystal structure (D4h19), due to the replacement of P for V, additional spectral features induced by the disorder of the mixed vanadate/phosphate system are also observed. In particular, all of the external lattice modes are characterized by a one-phonon-like behavior, while the behavior of the internal modes of the (V,P)O4 tetrahedron is two-phonon-like.
TL;DR: In this paper, a thin film of mixed manganese (mainly 4+) and vanadium (5+) oxides was heat-treated under vacuum at various temperatures between 25 and 400 °C.
Abstract: Thin films of mixed manganese (mainly 4+) and vanadium (5+) oxides deposited electrochemically on a platinum substrate have been heat-treated under vacuum at various temperatures between 25 and 400 °C. Electron spin resonance and x-ray photoelectron spectroscopy revealed that the reductive formation of Mn2+ occurs at 300 °C only in the presence of vanadium within the film. This phenomenon can be regarded as a result of electron transfer from V4+ ions generated thermally to neighboring Mn sites. Voltammetric response of the heat-treated Mn/V oxide film in borate solution was enhanced with increasing the number of potential cycles, and the steady-state current was much larger than that of pure manganese oxide. Vanadate ions were diffused from the film to maintain the charge balance during the repetition cycles. The resultant porous structure can allow easier mass transport of protons to electrically conductive Mn oxide surface, offering the improved charge–discharge performance of the electrode.
TL;DR: Because of its long-lasting effects, oral administration, and lack of side effects, vanadate/tea represents a potentially important alternative therapy for an insulin-deficient diabetic state.
Abstract: Oral administration of vanadate has a strong hypoglycemic effect but results in toxic side effects like life-threatening diarrhea. Tea is known to have potent antidiarrhea effects. We investigated the potential of suspending the vanadate in a tea decoction to reduce the diarrhetic action of vanadate. A concentrated extract of Lichee black tea was, therefore, added to sodium orthovanadate. Streptozotocin (STZ)-induced diabetic rats were orally gavaged with vanadate suspended in water or in the tea decoction, or with the tea extract alone. Blood glucose levels were assessed daily over 11 weeks with levels greater than 10 mmol/L warranting therapeutic intervention. Both the vanadate/water and vanadate/tea solutions acutely reduced blood glucose. The tea extract alone had no effect. The majority of vanadate/water-treated rats developed diarrhea and mortality rates approached 40%. Vanadate/tea-treated diabetic rats experienced no diarrhea or mortality and liver and kidney analyses (plasma ALT and creatinine, blood urea nitrogen [BUN], and urine-specific gravity) were normal. Animals treated with vanadate/tea retained blood glucose levels less than 10 mmol/L for an average of 24 consecutive days without subsequent treatments. Cataract formation was completely prevented. The mechanism of action of vanadate may have involved β-cell stimulation because vanadate/tea-treated diabetic rats exhibited normal plasma insulin levels. In summary, because of its long-lasting effects, oral administration, and lack of side effects, vanadate/tea represents a potentially important alternative therapy for an insuluin-defecient diabetic state.
TL;DR: In this article, the magnetic properties of the Zn2 FeV3O11 vanadate were studied using magnetization and electron paramagnetic resonance (EPR) measurements.
Abstract: The magnetic properties of the Zn2 FeV3O11 vanadate, characterized by a disordered distribution of diamagnetic Zn2 + and high-spin Fe3 + ions, are studied using magnetization and electron paramagnetic resonance (EPR) measurements. The dc susceptibility reveals antiferromagnetic interactions between Fe3 + spins with a Curie-Weiss temperature $\Theta = -58(1)$
K, followed by a transition to a frozen, spin-glass-like state at low temperature T
f
$\approx 2.55$
K, indicating an inhomogeneous magnetic ground state. The temperature variation of the EPR parameters confirms the antiferromagnetic coupling of Fe3 + spins at high temperatures, while a distinct divergence is observed at $T\approx 55$
K. This behavior is attributed to the inherent magnetic inhomogeneity of the system due to antiferromagnetic spin clusters.
TL;DR: Vanadate‐dependent bromoperoxidase from the alga Ascophyllum nodosum exhibits an unusually high shielding both for the native and the peroxo form of the enzyme, corresponding to the complexation of VO2+ to the Tf binding site and the Pp active centre, respectively.
Abstract: 51V quadrupolar central transition NMR spectra of buffered (pH 7.6-8.0) solutions of bovine apo-transferrin (Tf) and bovine prostatic acid phosphatase (Pp) treated with vanadate show normal features (chemical shifts between -515 and -542 ppm) corresponding to the complexation of VO2+ to the Tf binding site and the Pp active centre, respectively. Addition of H2O2 leads to the temporary formation of complexed VO(O2)+ (delta approximately -595). Vanadate-dependent bromoperoxidase from the alga Ascophyllum nodosum exhibits an unusually high shielding both for the native (delta = -931) and the peroxo form (delta = -1135) of the enzyme. A resonance at -471 ppm is traced back to an inactive form with oxovanadium(V) in a trigonal-bipyramidal array.
TL;DR: Kinetics of the inhibitory reaction showed the modification of a new group of essential residues only after removal of metal ions by EDTA, suggesting that the latter metal ion cannot be accommodated in the active site of Leishmania PGAM.
Abstract: Phosphoglycerate mutase (PGAM) activity in promastigotes of the protozoan parasite Leishmania mexicana is found only in the cytosol. It corresponds to a cofactor-independent PGAM as it is not stimulated by 2,3-bisphosphoglycerate and is susceptible to EDTA and resistant to vanadate. We have cloned and sequenced the gene and developed a convenient bacterial expression system and a high-yield purification protocol. Kinetic properties of the bacterially produced protein have been determined (3-phosphoglycerate: K(m) = 0.27 +/- 0.02 mm, k(cat) = 434 +/- 54 s(-1); 2-phosphoglycerate: K(m) = 0.11 +/- 0.03 mm, k(cat) = 199 +/- 24 s(-1)). The activity is inhibited by phosphate but is resistant to Cl(-) and SO(4) (2-). Inactivation by EDTA is almost fully reversed by incubation with CoCl(2) but not with MnCl(2), FeSO(4), CuSO(4), NiCl(2) or ZnCl(2). Alkylation by diethyl pyrocarbonate resulted in irreversible inhibition, but saturating concentrations of substrate provided full protection. Kinetics of the inhibitory reaction showed the modification of a new group of essential residues only after removal of metal ions by EDTA. The modified residues were identified by MS analysis of peptides generated by trypsin digestion. Two substrate-protected histidines in the proximity of the active site were identified (His136, His467) and, unexpectedly, also a distant one (His160), suggesting a conformational change in its environment. Partial protection of His467 was observed by the addition of 25 micro m CoCl(2) to the EDTA treated enzyme but not of 125 micro m MnCl(2), suggesting that the latter metal ion cannot be accommodated in the active site of Leishmania PGAM.
TL;DR: It is shown that with this configuration good intrachain coupling constants are obtained for the high-temperature phase and the interchain coupling in NaV2O5 is predicted to be approximately 34 K, ferromagnetic in nature.
Abstract: Magnetic interactions in ladder vanadates are determined with quantum chemical computational schemes using the embedded cluster model approach to represent the material. The available experimental data for calcium vanadate is accurately reproduced and the nature of the interladder interaction is established to be ferromagnetic. An analysis of the main contributions to the magnetic couplings is presented and the role of the covalently bonded apex oxygen is elucidated. In the sodium vanadate, the ground state configuration of the rungs is V-3d1–O-2p5–V-3d1. We show that with this configuration good intrachain coupling constants are obtained for the high-temperature phase. The interchain coupling in NaV2O5 is predicted to be ≈34 K, ferromagnetic in nature.
TL;DR: In this paper, the space groups of β- and γ-Zn 3 (VO 4 ) 2 particles in vanadium oxide-doped zinc oxide varistors were determined using convergent-beam electron diffraction.
Abstract: Convergent-beam electron diffraction has been used to determine the space groups of β- and γ-Zn 3 (VO 4 ) 2 particles in vanadium oxide-doped zinc oxide varistors. The crystal structure of β-Zn 3 (VO 4 ) 2 has been determined to be monoclinic with space group P2 1 and lattice parameters of a = 9.80 A, b = 8.34 A, c = 10.27 A, and β = 115.8°, whereas that of γ-Zn 3 (VO 4 ) 2 is monoclinic with space group Cm and a = 10.40 A, b = 8.59 A, c = 9.44 A, and β = 98.8°. Energy dispersive X-ray microanalysis of these two phases shows significant deviations from their expected stoichiometry. It is apparent that the β-phase is, in fact, the metastable Zn 4 V 2 O 9 phase, whereas the γ-phase either is a new oxide that consists of zinc, vanadium, and manganese or, more likely, is a zinc vanadate phase with a Zn:V atomic ratio of 1:1 that has the ability to go into solid solution with manganese.
TL;DR: Data indicate that vanadate induces Rho A activation probably via protein tyrosine phosphorylation and the subsequent contraction through increases in the level of MLCosphorylation.
TL;DR: Culture with tungstate and molybdate increased cellular insulin content and enhanced basal insulin release and the responsiveness to glucose and a wide range of other secretagogues, suggesting significant effects of ultratrace elements on pancreatic beta cells that may contribute to their antihyperglycemic action.
Abstract: The ultratrace elements vanadate, tungstate, and molybdate exhibit significant antihyperglycemic effects in both type 1 and 2 diabetic animals, but possible effects on the function of pancreatic beta cells are understudied. In the present study, clonal BRIN BD11 cells were cultured for 3 days with each ultratrace element to establish doses lacking detrimental effects on viable beta cell mass. Vanadate treatment (4 micromol/L) had no effect on cellular insulin content but improved glucose-induced insulin secretory responsiveness. However, insulin secretion mediated by PKA and PKC activation was desensitized in vanadate-treated cells. Culture with tungstate (300 micromol/L) and molybdate (1 mmol/L) increased cellular insulin content and enhanced basal insulin release and the responsiveness to glucose and a wide range of other secretagogues. These observations suggest significant effects of ultratrace elements on pancreatic beta cells that may contribute to their antihyperglycemic action.
Patent•
28 Apr 2004
TL;DR: In this paper, a method for the synthesis of nanoparticulate metal(III) vanadates or vanadate/phosophate mixed crystals, comprising the reaction in a reaction medium of a reactive vanadite source and optionally a phosphate source, was presented.
Abstract: The present invention relates to a method for the production of nanoparticulate metal(III) vanadates or vanadate/phosophate mixed crystals, comprising the reaction in a reaction medium of a reactive vanadate source and optionally a phosphate source dissolvable or dispersible in the reaction medium and of a reactive metal(III) salt dissolvable or dispersible in the reaction medium under heating, wherein the reaction medium contains water and a polyol in a volume ratio of 20/80 to 90/10, and the particles thereby obtained The synthesis provides a high yield of metal(III) vanadate or vanadate/phosphate having a narrow particle size distribution Doped embodiments thereof are distinguished by excellent luminescence properties
TL;DR: In this paper, point mutants with alterations to amino acid residues Thr(247), Pro(248), Glu(340), Asp(813), Arg(819), and Arg( 822) of sarcoplasmic reticulum Ca(2+)-ATPase were analyzed by transient kinetic measurements.