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Exposure to Molybdate Results in Metabolic Disorder: An Integrated Study of the Urine Elementome and Serum Metabolome in Mice. TOXICS 2024; 12:288. [PMID: 38668511 PMCID: PMC11053804 DOI: 10.3390/toxics12040288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 04/04/2024] [Accepted: 04/12/2024] [Indexed: 04/29/2024]
Abstract
The increasing use of molybdate has raised concerns about its potential toxicity in humans. However, the potential toxicity of molybdate under the current level of human exposure remains largely unknown. Endogenous metabolic alterations that are caused in humans by environmental exposure to pollutants are associated with the occurrence and progression of many diseases. This study exposed eight-week-old male C57 mice to sodium molybdate at doses relevant to humans (0.01 and 1 mg/kg/day) for eight weeks. Inductively coupled plasma mass spectrometry (ICP-MS) and ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS) were utilized to assess changes in urine element levels and serum metabolites in mice, respectively. A total of 838 subjects from the NHANES 2017-2018 population database were also included in our study to verify the associations between molybdenum and cadmium found in mice. Analysis of the metabolome in mice revealed that four metabolites in blood serum exhibited significant changes, including 5-aminolevulinic acid, glycolic acid, l-acetylcarnitine, and 2,3-dihydroxypropyl octanoate. Analysis of the elementome revealed a significant increase in urine levels of cadmium after molybdate exposure in mice. Notably, molybdenum also showed a positive correlation with cadmium in humans from the NHANES database. Further analysis identified a positive correlation between cadmium and 2,3-dihydroxypropyl octanoate in mice. In conclusion, these findings suggest that molybdate exposure disrupted amino acid and lipid metabolism, which may be partially mediated by molybdate-altered cadmium levels. The integration of elementome and metabolome data provides sensitive information on molybdate-induced metabolic disorders and associated toxicities at levels relevant to human exposure.
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Crystal structure of a layered phosphate molybdate K 2Gd(PO 4)(MoO 4). Acta Crystallogr E Crystallogr Commun 2024; 80:117-119. [PMID: 38333117 PMCID: PMC10848991 DOI: 10.1107/s2056989023011106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 12/27/2023] [Indexed: 02/10/2024]
Abstract
The title compound dipotassium gadolinium(III) phosphate(V) molybdate(VI), K2Gd(PO4)(MoO4), was synthesized from a high-temperature melt starting from GdF3 as a source of gadolinium. Its structure is isotypic with other M I 2 M III(M VIO4)(PO4) compounds, where M I = Na, K or Cs, and M III = rare-earth cation, M VI = Mo or W. The three-dimensional framework is built up from [Gd(PO4)(MoO4)] anionic sheets, which are organized by adhesion of [GdPO4] layers and [MoO4] tetra-hedra stacked above and below these layers. The inter-stitial space is occupied by K cations having eightfold oxygen coordination. The polyhedron of GdO8 was estimated to be a triangular dodeca-hedron by the continuous shape measurement method.
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Molybdenum - a scoping review for Nordic Nutrition Recommendations 2023. Food Nutr Res 2023; 67:10326. [PMID: 38187804 PMCID: PMC10770642 DOI: 10.29219/fnr.v67.10326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 01/02/2023] [Accepted: 10/25/2023] [Indexed: 01/09/2024] Open
Abstract
Molybdenum is an essential element in the form of the molybdenum cofactor (Moco). In humans, Moco is required for four enzymes: xanthine oxidase (XO), aldehyde oxidase, sulfite oxidase (SO), and mitochondrial amidoxime-reducing component (mARC). The enzymes are involved in the oxidation of purines to uric acid, metabolism of aromatic aldehydes and heterocyclic compounds, and in the catabolism of sulfur amino acids. Molybdenum cofactor deficiency is a rare autosomal recessive syndrome due to a defective synthesis of Moco, resulting in a deficiency of all the molybdoenzymes. There are no reports on clinical signs of dietary molybdenum deficiency in otherwise healthy humans. Water-soluble molybdate is efficiently absorbed from the digestive tract. The body retention is regulated by urinary excretion. Plasma molybdenum reflects long-term intake and 24-h urinary excretion is related to recent intake. There are no biochemical markers of molybdenum status. Cereal products are the main contributors to molybdenum dietary intake, estimated to 100-170 μg/day in Nordic studies. Little data are available on molybdenum toxicity in humans. A tolerable upper intake level of molybdenum has been based on reproductive toxicity in rats, but the effects have not been reproduced in more recent studies. The U.S. Institute of Medicine (IOM, present National Academy of Sciences, Engineering, and Medicine; NASEM) established a Recommended Dietary Allowance of 45 μg/day in adult men and women in 2001, based on a small study reporting urinary excretion in balance with intake at 22 μg/day. The European Food Safety Authority (EFSA) considered in 2013 the evidence to be insufficient to derive an Average Requirement and a Population Reference Intake, but proposed an Adequate Intake of 65 μg/day for adults.
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High Quantum Yield Shortwave Infrared Luminescent Tracers for Improved Sorting of Plastic Waste. ACS APPLIED MATERIALS & INTERFACES 2023; 15:43985-43993. [PMID: 37674324 DOI: 10.1021/acsami.3c07387] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
Abstract
More complete recycling of plastic waste is possible only if new technologies that go beyond state-of-the-art near-infrared (NIR) sorting are developed. For example, tracer-based sorting is a new technology that explores the upconversion or down-shift luminescence of special tracers based on inorganic materials codoped with lanthanide ions. Specifically, down-shift tracers emit in the shortwave infrared (SWIR) spectral range and can be detected using a SWIR camera preinstalled in a state-of-the-art sorting machine for NIR sorting. In this study, we synthesized a very efficient SWIR tracer by codoping Li3Ba2Gd3 (MoO4)8 with Yb3+ and Er3+, where Yb3+ is a synthesizer ion (excited near 976 nm) and Er3+ emits near 1550 nm. Fine-tuning of the doping concentration resulted in a tracer (Li3Ba2Gd(3-x-y)(MoO4)8:xYb3+, yEr3+, where x = 0.2 and y = 0.4) with a high photoluminescence quantum yield for 1550 nm emission of 70% (using 976 nm excitation). This tracer was used to mark plastic objects. When the object was illuminated by a halogen lamp and a 976 nm laser, the three parts could be easily distinguished based on reflectance and luminescence spectra in the SWIR range: a plastic bottle made of polyethylene terephthalate, a bottle cap made of high-density polyethylene, and a label made of the tracer Li3Ba2Gd3(MoO4)8:Yb3+, Er3+. Importantly, the use of the tracer in sorting may require only the installation of a 976 nm laser in a state-of-the-art NIR sorting system.
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Effects of duration of exposure, co-supplementation with iron and Nippostrongylus brasiliensis infection on accumulation of trichloroacetic acid-insoluble copper in rats given molybdate in drinking water. J Comp Pathol 2023; 203:23-25. [PMID: 37236008 DOI: 10.1016/j.jcpa.2023.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 12/28/2022] [Accepted: 02/10/2023] [Indexed: 05/28/2023]
Abstract
Thiolation can convert molybdate (MoO4) into a series of thiomolybdates (MoSxO4-x) in the rumen, terminating in tetrathiomolybdate (MoS4), a potent antagonist of copper absorption and, if absorbed, donor of reactive sulphide in tissues. Systemic exposure to MoS4 increases trichloroacetic acid-insoluble copper (TCAI Cu) concentrations in the plasma of ruminants and induction of TCAI Cu in rats given MoO4 in drinking water would support the hypothesis that rats, like ruminants, can thiolate MoO4. Data on TCAI Cu are presented from two experiments involving MoO4 supplementation that had broader objectives. In experiment 1, plasma Cu concentrations (P Cu) tripled in female rats infected with Nippostrongylus brasiliensis after only 5 days exposure to drinking water containing 70 mg Mo L-1, due largely to an increase in TCAI Cu; activities of erythrocyte superoxide dismutase and plasma caeruloplasmin oxidase (CpOA) were unaffected. Exposure for 45-51 days did not raise P Cu further but TCA-soluble (TCAS) Cu concentrations increased temporarily 5 days post infection (dpi) and weakened the linear relationship between CpOA and TCAS Cu. In experiment 2, infected rats were given less MoO4 (10 mg Mo L-1), with or without iron (Fe, 300 mg L-1), for 67 days and killed 7 or 9 dpi. P Cu was again tripled by MoO4 but co-supplementation with Fe reduced TCAI Cu from 65 ± 8.9 to 36 ± 3.8 μmol L-l. Alone, Fe and MoO4 each reduced TCAS Cu in females and males when values were higher (7 and 9 dpi, respectively). Thiolation probably occurred in the large intestine but was inhibited by precipitation of sulphide as ferrous sulphide. Fe alone may have inhibited caeruloplasmin synthesis during the acute phase response to infection, which impacts thiomolybdate metabolism.
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Adsorption Removal of Mo(VI) from an Aqueous Solution by Alumina with the Subsequent Regeneration of the Adsorbent. Int J Mol Sci 2023; 24:ijms24108700. [PMID: 37240043 DOI: 10.3390/ijms24108700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 05/02/2023] [Accepted: 05/10/2023] [Indexed: 05/28/2023] Open
Abstract
Industrial wastewater is the main source of an excessive amount of molybdenum (Mo) in natural ecosystems. It is necessary to remove Mo from wastewater before it is discharged into the environment. Molybdate ion(VI) is the most common form of Mo in natural reservoirs and industrial wastewater. In this work, the sorption removal of Mo(VI) from an aqueous medium was evaluated using aluminum oxide. The influence of such factors as the pH of the solution and the temperature was evaluated. Three adsorption isotherms, namely, Langmuir, Freundlich and Temkin, were used to describe the experimental results. It was found that the pseudo-first order kinetic model better fits the kinetic data of the adsorption process, and the maximum Mo(VI) adsorption capacity was 31 mg/g at 25 °C and pH 4. The thermodynamic parameters indicated that the process of Mo(VI) adsorption on Al2O3 was exothermic and spontaneous. It was shown that the adsorption of Mo strongly depends on pH. The most effective adsorption was observed at pH values below 7. Experiments on adsorbent regeneration showed that Mo(VI) can be effectively desorbed from the aluminum oxide surface into a phosphate solution in a wide range of pH values. After the desorption of Mo(VI) in a phosphate solution, alumina was found to be suitable for repeating the procedure at least five times.
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Desaturation of the Sphingofungin Polyketide Tail Results in Increased Serine Palmitoyltransferase Inhibition. Microbiol Spectr 2022; 10:e0133122. [PMID: 36121228 PMCID: PMC9603476 DOI: 10.1128/spectrum.01331-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 09/02/2022] [Indexed: 12/30/2022] Open
Abstract
Serine palmitoyltransferase catalyzes the first step of the sphingolipid biosynthesis. Recently, sphingolipid homeostasis has been connected to several human diseases, making serine palmitoyltransferases an interesting therapeutic target. Known and efficient serine palmitoyltransferase-inhibitors are sphingofungins, a group of natural products isolated from fungi. To further characterize newly isolated sphingofungins, we designed an easy to use colorimetric serine palmitoyltransferase activity assay using FadD, which can be performed in 96-well plates. Because sphingofungins exert antifungal activitiy as well, we compared the in vitro assay results with an in vivo growth assay using Saccharomyces cerevisiae. The reported experiments showed differences among the assayed sphingofungins, highlighting an increase of activity based on the saturation levels of the polyketide tail. IMPORTANCE Targeting the cellular sphingolipid metabolism is often discussed as a potential approach to treat associated human diseases such as cancer and Alzheimer's disease. Alternatively, it is also a possible target for the development of antifungal compounds, which are direly needed. A central role is played by the serine palmitoyltransferase, which catalyzes the initial and rate limiting step of sphingolipid de novo synthesis and, as such, the development of inhibitory compounds for this enzyme is of interest. Our work here established an alternative approach for determining the activity of serine palmitoyltransferase adding another tool for the validation of its inhibition. We also determined the effect of different modifications to sphingofungins on their inhibitory activity against serine palmitoyltransferase, revealing important differences on said activity against enzymes of bacterial and fungal origin.
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Effects of Raising or Lowering Molybdenum Status on Outcome of Acute Infection with Nippostrongylus brasiliensis in Mature Rats. J Comp Pathol 2022; 196:41-49. [PMID: 36008043 DOI: 10.1016/j.jcpa.2022.06.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 04/25/2022] [Accepted: 06/15/2022] [Indexed: 11/23/2022]
Abstract
Molybdate (Mo+) supplements can suppress or enhance nematode infections in ruminants, depending on exposure level, but there have been no investigations in non-ruminants. Three groups of 16 mature rats were each fed a commercial diet and given Mo+ (10 mg Mo/l), tungstate (a molybdenum [Mo] antagonist) (MoO4, 350 mg W/l) or no supplement (C) via drinking water for 40 days before acute infection with 3,600 Nippostrongylus brasiliensis larvae. Group Mo- also received allopurinol (1 g/l), a molybdenoenzyme inhibitor, from 4 days post infection (dpi). Subgroups of four rats from each group were killed at 7-14 dpi. A group of six rats was left untreated and uninfected and subgroups killed 10 or 12 dpi. Infection reduced intakes of food and water but impacts were greatest in group Mo-. Median worm counts in groups C, Mo- and Mo+ were 900, 941 and 510, respectively, at 7 dpi and 9, 40 and 0 (P = 0.05) at 10 dpi. Median faecal egg counts were consistently lowest in group Mo+. Worm weight was reduced (P <0.05), worm tissue protease increased and superoxide dismutase activities increased in worm (P < 0.01) and host duodenal homogenates (P < 0.01) from group Mo+. In group Mo-, liver Mo concentration decreased, duodenal xanthine oxidoreductase activity (DXOR) became totally inhibited and plasma uric acid was barely detectable at 10 dpi. Plasma mast cell protease activity and duodenal malonyldialdehyde concentrations, markers of inflammation, were increased by nematode infection (P <0.001) but unaffected by water treatments. Liver Mo, liver copper (Cu) and plasma Cu concentrations were increased in group Mo+ and plasma Cu concentration was increased in group Mo- suggesting systemic exposure to partially thiolated MoO4 and WO4. Supplementary MoO4 impaired larval establishment and changed parasite biochemistry without affecting the inflammatory response to infection but may have required partial thiolation to do so. Rats did not rely on DXOR activity to expel N. brasiliensis.
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Structural and Spectroscopic Effects of Li + Substitution for Na + in Li xNa 1-xCaGd 0.5Ho 0.05Yb 0.45(MoO 4) 3 Scheelite-Type Upconversion Phosphors. Molecules 2021; 26:molecules26237357. [PMID: 34885937 PMCID: PMC8659099 DOI: 10.3390/molecules26237357] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 11/24/2021] [Accepted: 11/30/2021] [Indexed: 11/25/2022] Open
Abstract
A set of new triple molybdates, LixNa1-xCaGd0.5(MoO4)3:Ho3+0.05/Yb3+0.45, was successfully manufactured by the microwave-accompanied sol–gel-based process (MAS). Yellow molybdate phosphors LixNa1-xCaGd0.5(MoO4)3:Ho3+0.05/Yb3+0.45 with variation of the LixNa1-x (x = 0, 0.05, 0.1, 0.2, 0.3) ratio under constant doping amounts of Ho3+ = 0.05 and Yb3+ = 0.45 were obtained, and the effect of Li+ on their spectroscopic features was investigated. The crystal structures of LixNa1-xCaGd0.5(MoO4)3:Ho3+0.05/Yb3+0.45 (x = 0, 0.05, 0.1, 0.2, 0.3) at room temperature were determined in space group I41/a by Rietveld analysis. Pure NaCaGd0.5Ho0.05Yb0.45(MoO4)3 has a scheelite-type structure with cell parameters a = 5.2077 (2) and c = 11.3657 (5) Å, V = 308.24 (3) Å3, Z = 4. In Li-doped samples, big cation sites are occupied by a mixture of (Li,Na,Gd,Ho,Yb) ions, and this provides a linear cell volume decrease with increasing Li doping level. The evaluated upconversion (UC) behavior and Raman spectroscopic results of the phosphors are discussed in detail. Under excitation at 980 nm, the phosphors provide yellow color emission based on the 5S2/5F4 → 5I8 green emission and the 5F5 → 5I8 red emission. The incorporated Li+ ions gave rise to local symmetry distortion (LSD) around the cations in the substituted crystalline structure by the Ho3+ and Yb3+ ions, and they further affected the UC transition probabilities in triple molybdates LixNa1-xCaGd0.5(MoO4)3:Ho3+0.05/Yb3+0.45. The complex UC intensity dependence on the Li content is explained by the specificity of unit cell distortion in a disordered large ion system within the scheelite crystal structure. The Raman spectra of LixNa1-xCaGd0.5(MoO4)3 doped with Ho3+ and Yb3+ ions were totally superimposed with the luminescence signal of Ho3+ ions in the range of Mo–O stretching vibrations, and increasing the Li+ content resulted in a change in the Ho3+ multiplet intensity. The individual chromaticity points (ICP) for the LiNaCaGd(MoO4)3:Ho3+,Yb3+ phosphors correspond to the equal-energy point in the standard CIE (Commission Internationale de L’Eclairage) coordinates.
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Sulfate and Molybdate Incorporation at the Calcite-Water Interface: Insights from Ab Initio Molecular Dynamics. ACS EARTH & SPACE CHEMISTRY 2021; 5:2066-2073. [PMID: 34476320 PMCID: PMC8397469 DOI: 10.1021/acsearthspacechem.1c00131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 06/29/2021] [Accepted: 07/13/2021] [Indexed: 06/13/2023]
Abstract
Sulfur and molybdenum trace impurities in speleothems (stalagmites and stalactites) can provide long and continuous records of volcanic activity, which are important for past climatic and environmental reconstructions. However, the chemistry governing the incorporation of the trace element-bearing species into the calcium carbonate phases forming speleothems is not well understood. Our previous work has shown that substitution of tetrahedral oxyanions [XO4]2- (X = S and Mo) replacing [CO3]2- in CaCO3 bulk phases (except perhaps for vaterite) is thermodynamically unfavorable with respect to the formation of competing phases, due to the larger size and different shape of the [XO4]2- tetrahedral anions in comparison with the flat [CO3]2- anions, which implied that most of the incorporation would happen at the surface rather than at the bulk of the mineral. Here, we present an ab initio molecular dynamics study, exploring the incorporation of these impurities at the mineral-water interface. We show that the oxyanion substitution at the aqueous calcite (10.4) surface is clearly favored over bulk incorporation, due to the lower structural strain on the calcium carbonate solid. Incorporation at surface step sites is even more favorable for both oxyanions, thanks to the additional interface space afforded by the surface line defect to accommodate the tetrahedral anion. Differences between sulfate and molybdate substitutions can be mostly explained by the size of the anions. The molybdate oxyanion is more difficult to incorporate in the calcite bulk than the smaller sulfate oxyanion. However, when molybdate is substituted at the surface, the elastic cost is avoided because the oxyanion protrudes out of the surface and gains stability via the interaction with water at the interface, which in balance results in more favorable surface substitution for molybdate than for sulfate. The detailed molecular-level insights provided by our calculations will be useful to understand the chemical basis of S- and Mo-based speleothem records.
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Combination of Trace Metal to Improve Solventogenesis of Clostridium carboxidivorans P7 in Syngas Fermentation. Front Microbiol 2020; 11:577266. [PMID: 33101253 PMCID: PMC7546793 DOI: 10.3389/fmicb.2020.577266] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 09/04/2020] [Indexed: 11/13/2022] Open
Abstract
Higher alcohols such as butanol (C4 alcohol) and hexanol (C6 alcohol) are superior biofuels compared to ethanol. Clostridium carboxidivorans P7 is a typical acetogen capable of producing C4 and C6 alcohols natively. In this study, the composition of trace metals in culture medium was adjusted, and the effects of these adjustments on artificial syngas fermentation by C. carboxidivorans P7 were investigated. Nickel and ferrous ions were essential for growth and metabolite synthesis during syngas fermentation by P7. However, a decreased dose of molybdate improved alcohol fermentation performance by stimulating carbon fixation and solventogenesis. In response to the modified trace metal composition, cells grew to a maximum OD600 nm of 1.6 and accumulated ethanol and butanol to maximum concentrations of 2.0 and 1.0 g/L, respectively, in serum bottles. These yields were ten-fold higher than the yields generated using the original composition of trace metals. Furthermore, 0.5 g/L of hexanol was detected at the end of fermentation. The results from gene expression experiments examining genes related to carbon fixation and organic acid and solvent synthesis pathways revealed a dramatic up-regulation of the Wood-Ljungdahl pathway (WLP) gene cluster, the bcs gene cluster, and a putative CoA transferase and butanol dehydrogenase, thereby indicating that both de novo synthesis and acid re-assimilation contributed to the significantly elevated accumulation of higher alcohols. The bdh35 gene was speculated to be the key target for butanol synthesis during solventogenesis.
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8-Hydroxyquinoline-2-Carboxylic Acid as Possible Molybdophore: A Multi-Technique Approach to Define Its Chemical Speciation, Coordination and Sequestering Ability in Aqueous Solution. Biomolecules 2020; 10:biom10060930. [PMID: 32570991 PMCID: PMC7356571 DOI: 10.3390/biom10060930] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 06/17/2020] [Indexed: 11/23/2022] Open
Abstract
8-hydroxyquinoline-2-carboxylic acid (8-HQA) has been found in high concentrations (0.5–5.0 mmol·dm−3) in the gut of Noctuid larvae (and in a few other lepidopterans), in which it is proposed to act as a siderophore. Since it is known that many natural siderophores are also involved in the uptake and metabolism of other essential elements than iron, this study reports some results on the investigation of 8-HQA interactions with molybdate (MoO42−, i.e., the main molybdenum form in aqueous environments), in order to understand the possible role of this ligand as molybdophore. A multi-technique approach has been adopted, in order to derive a comprehensive set of information necessary to assess the chemical speciation of the 8-HQA/MoO42− system, as well as the coordination behavior and the sequestering ability of 8-HQA towards molybdate. Chemical speciation studies have been performed in KCl(aq) at I = 0.2 mol·dm−3 and T = 298.15 K by ISE-H+ (glass electrode) potentiometric and UV/Vis spectrophotometric titrations. CV (Cyclic Voltammetry), DP-ASV (Differential Pulse-Anodic Stripping Voltammetry), ESI-MS experiments and quantum mechanical calculations have been also performed to derive information about the nature and possible structure of species formed. These results are also compared with those reported for the 8-HQA/Fe3+ system in terms of chemical speciation and sequestering ability of 8-HQA.
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Transitional States in Ligand-Dependent Transformation of the Aryl Hydrocarbon Receptor into Its DNA-Binding Form. Int J Mol Sci 2020; 21:ijms21072474. [PMID: 32252465 PMCID: PMC7177239 DOI: 10.3390/ijms21072474] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 03/20/2020] [Accepted: 03/30/2020] [Indexed: 01/03/2023] Open
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that mediates the biological and toxicological effects of an AhR lacking the entire PASB structurally diverse chemicals, including halogenated aromatic hydrocarbons. Ligand-dependent transformation of the AhR into its DNA binding form involves a ligand-dependent conformational change, heat shock protein 90 (hsp90), dissociation from the AhR complex and AhR dimerization with the AhR nuclear translocator (ARNT) protein. The mechanism of AhR transformation was examined using mutational approaches and stabilization of the AhR:hsp90 complex with sodium molybdate. Insertion of a single mutation (F281A) in the hsp90-binding region of the AhR resulted in its constitutive (ligand-independent) transformation/DNA binding in vitro. Mutations of AhR residues within the Arg-Cys-rich region (R212A, R217A, R219A) and Asp371 (D371A) impaired AhR transformation without a significant effect on ligand binding. Stabilization of AhR:hsp90 binding with sodium molybdate decreased transformation/DNA binding of the wild type AhR but had no effect on constitutively active AhR mutants. Interestingly, transformation of the AhR in the presence of molybdate allowed detection of an intermediate transformation ternary complex containing hsp90, AhR, and ARNT. These results are consistent with a stepwise transformation mechanism in which binding of ARNT to the liganded AhR:hsp90 complex results in a progressive displacement of hsp90 and conversion of the AhR into its high affinity DNA binding form. The available molecular insights into the signaling mechanism of other Per-ARNT-Sim (PAS) domains and structural information on hsp90 association with other client proteins are consistent with the proposed transformation mechanism of the AhR.
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The Different Effects of Substrates and Nucleotides on the Complex Formation of ABC Transporters. Structure 2019; 27:651-659.e3. [PMID: 30799075 PMCID: PMC6453779 DOI: 10.1016/j.str.2019.01.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 11/17/2018] [Accepted: 01/18/2019] [Indexed: 11/27/2022]
Abstract
The molybdate importer (ModBC-A of Archaeoglobus fulgidus) and the vitamin B12 importer (BtuCD-F of Escherichia coli) are members of the type I and type II ABC importer families. Here we study the influence of substrate and nucleotide binding on complex formation and stability. Using native mass spectrometry we show that the interaction between the periplasmic substrate-binding protein (SBP) ModA and the transporter ModBC is dependent upon binding of molybdate. By contrast, vitamin B12 disrupts interactions between the transporter BtuCD and the SBP BtuF. Moreover, while ATP binds cooperatively to BtuCD-F, and acts synergistically with vitamin B12 to destabilize the BtuCD-F complex, no effect is observed for ATP binding on the stability of ModBC-A. These observations not only highlight the ability of mass spectrometry to capture these importer-SBP complexes but allow us to add molecular detail to proposed transport mechanisms.
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Blue-Light-Excited Eu 3+/Sm 3+ Co-Doped NaLa(MoO₄)₂ Phosphors: Synthesis, Characterizations and Red Emission Enhancement for WLEDs. MATERIALS 2018; 11:ma11071090. [PMID: 29949935 PMCID: PMC6073863 DOI: 10.3390/ma11071090] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 06/07/2018] [Accepted: 06/15/2018] [Indexed: 11/19/2022]
Abstract
The system NaLa(MoO4)2:Eu3+/Sm3+ phosphors were prepared by solid-state reaction followed by heat treatment at 450–600 °C. As shown by X-ray powder diffraction, the phosphors had a body-centered tetragonal structure, high phase purity and high crystallinity. The photoluminescence measurements carried out under excitation at 464 nm indicated the main emission at about 615 nm corresponding to the electric dipole transition 5D0→7F2 of Eu3+, which agreed well with the emission wavelengths of the GaN-based blue LED chips. In NaLa(MoO4)2:Eu3+/Sm3+ phosphors, Sm3+ can efficiently transfer excitation energy to Eu3+, which resulted in a significant improvement of the fluorescence intensity, and the fluorescence intensity of the phosphors calcined at 550 °C maximized at the doping concentrations of Eu3+ and Sm3+ of 15.0 and 2.0 mol %, respectively. The decay curves and CIE (Commission Internationale de L’ Eclairage) coordinates of Sm3+ or/and Eu3+ doped phosphors were analyzed for the investigation of the energy transfer mechanism and color variation trend. Thus, NaLa(MoO4)2:Eu3+,Sm3+ can be classified as a potential red-emitting phosphor for white light-emitting diodes (WLEDs).
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Typical Soil Redox Processes in Pentachlorophenol Polluted Soil Following Biochar Addition. Front Microbiol 2018; 9:579. [PMID: 29636746 PMCID: PMC5880936 DOI: 10.3389/fmicb.2018.00579] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 03/13/2018] [Indexed: 11/28/2022] Open
Abstract
Reductive dechlorination is the primary pathway for environmental removal of pentachlorophenol (PCP) in soil under anaerobic condition. This process has been verified to be coupled with other soil redox processes of typical biogenic elements such as carbon, iron and sulfur. Meanwhile, biochar has received increasing interest in its potential for remediation of contaminated soil, with the effect seldom investigated under anaerobic environment. In this study, a 120-day anaerobic incubation experiment was conducted to investigate the effects of biochar on soil redox processes and thereby the reductive dechlorination of PCP under anaerobic condition. Biochar addition (1%, w/w) enhanced the dissimilatory iron reduction and sulfate reduction while simultaneously decreased the PCP reduction significantly. Instead, the production of methane was not affected by biochar. Interestingly, however, PCP reduction was promoted by biochar when microbial sulfate reduction was suppressed by addition of typical inhibitor molybdate. Together with Illumina sequencing data regarding analysis of soil bacteria and archaea responses, our results suggest that under anaerobic condition, the main competition mechanisms of these typical soil redox processes on the reductive dechlorination of PCP may be different in the presence of biochar. In particularly, the effect of biochar on sulfate reduction process is mainly through promoting the growth of sulfate reducer (Desulfobulbaceae and Desulfobacteraceae) but not as an electron shuttle. With the supplementary addition of molybdate, biochar application is suggested as an improved strategy for a better remediation results by coordinating the interaction between dechlorination and its coupled soil redox processes, with minimum production of toxic sulfur reducing substances and relatively small emission of greenhouse gas (CH4) while maximum removal of PCP.
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The Preparation and Optical Properties of Novel LiLa(MoO4)2:Sm3+,Eu3+ Red Phosphor. MATERIALS 2018; 11:ma11020297. [PMID: 29443910 PMCID: PMC5848994 DOI: 10.3390/ma11020297] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 02/08/2018] [Accepted: 02/12/2018] [Indexed: 11/16/2022]
Abstract
Novel LiLa1-x-y(MoO4)2:xSm3+,yEu3+ (in short: LL1-x-yM:xSm3+,yEu3+) double molybdate red phosphors were synthesized by a solid-state reaction at as low temperature as 610 °C. The optimal doping concentration of Sm3+ in LiLa1-x(MoO4)2:xSm3+ (LL1-xM:xSm3+) phosphor is x = 0.05 and higher concentrations lead to emission quenching by the electric dipole-electric dipole mechanism. In the samples co-doped with Eu3+ ions, the absorption spectrum in the near ultraviolet and blue regions became broader and stronger than these of the Sm3+ single-doped samples. The efficient energy transfer from Sm3+ to Eu3+ was found and the energy transfer efficiency was calculated. Under the excitation at 403 nm, the chromaticity coordinates of LL0.95-yM:0.05Sm3+,yEu3+ approach to the NTSC standard values (0.670, 0.330) continuously with increasing Eu3+ doping concentration. The phosphor exhibits high luminous efficiency under near UV or blue light excitation and remarkable thermal stability. At 150 °C, the integrated emission intensity of the Eu3+ remained 85% of the initial intensity at room temperature and the activation energy is calculated to be 0.254 eV. The addition of the LL0.83M:0.05Sm3+,0.12Eu3+ red phosphors can improve the color purity and reduce the correlated color temperature of WLED lamps. Hence, LL1-x-yM:xSm3+,yEu3+ is a promising WLED red phosphor.
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Bacterial PerO Permeases Transport Sulfate and Related Oxyanions. J Bacteriol 2017; 199:JB.00183-17. [PMID: 28461447 DOI: 10.1128/jb.00183-17] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 04/22/2017] [Indexed: 01/13/2023] Open
Abstract
Rhodobacter capsulatus synthesizes the high-affinity ABC transporters CysTWA and ModABC to specifically import the chemically related oxyanions sulfate and molybdate, respectively. In addition, R. capsulatus has the low-affinity permease PerO acting as a general oxyanion transporter, whose elimination increases tolerance to molybdate and tungstate. Although PerO-like permeases are widespread in bacteria, their function has not been examined in any other species to date. Here, we present evidence that PerO permeases from the alphaproteobacteria Agrobacterium tumefaciens, Dinoroseobacter shibae, Rhodobacter sphaeroides, and Sinorhizobium meliloti and the gammaproteobacterium Pseudomonas stutzeri functionally substitute for R. capsulatus PerO in sulfate uptake and sulfate-dependent growth, as shown by assimilation of radioactively labeled sulfate and heterologous complementation. Disruption of perO genes in A. tumefaciens, R. sphaeroides, and S. meliloti increased tolerance to tungstate and, in the case of R. sphaeroides, to molybdate, suggesting that heterometal oxyanions are common substrates of PerO permeases. This study supports the view that bacterial PerO permeases typically transport sulfate and related oxyanions and, hence, form a functionally conserved permease family.IMPORTANCE Despite the widespread distribution of PerO-like permeases in bacteria, our knowledge about PerO function until now was limited to one species, Rhodobacter capsulatus In this study, we showed that PerO proteins from diverse bacteria are functionally similar to the R. capsulatus prototype, suggesting that PerO permeases form a conserved family whose members transport sulfate and related oxyanions.
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Effect of Transition Metal Cations on Stability Enhancement for Molybdate-Based Hybrid Supercapacitor. ACS APPLIED MATERIALS & INTERFACES 2017; 9:17977-17991. [PMID: 28481523 DOI: 10.1021/acsami.7b03836] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The race for better electrochemical energy storage systems has prompted examination of the stability in the molybdate framework (MMoO4; M = Mn, Co, or Ni) based on a range of transition metal cations from both computational and experimental approaches. Molybdate materials synthesized with controlled nanoscale morphologies (such as nanorods, agglomerated nanostructures, and nanoneedles for Mn, Co, and Ni elements, respectively) have been used as a cathode in hybrid energy storage systems. The computational and experimental data confirms that the MnMoO4 crystallized in β-form with α-MnMoO4 type whereas Co and Ni cations crystallized in α-form with α-CoMoO4 type structure. Among the various transition metal cations studied, hybrid device comprising NiMoO4 vs activated carbon exhibited excellent electrochemical performance having the specific capacitance 82 F g-1 at a current density of 0.1 A g-1 but the cycling stability needed to be significantly improved. The specific capacitance of the NiMoO4 electrode material is shown to be directly related to the surface area of the electrode/electrolyte interface, but the CoMoO4 and MnMoO4 favored a bulk formation that could be suitable for structural stability. The useful insights from the electronic structure analysis and effective mass have been provided to demonstrate the role of cations in the molybdate structure and its influence in electrochemical energy storage. With improved cycling stability, NiMoO4 can be suitable for renewable energy storage. Overall, this study will enable the development of next generation molybdate materials with multiple cation substitution resulting in better cycling stability and higher specific capacitance.
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Crystal structure of alluaudite-type Na4Co(MoO4)3. Acta Crystallogr Sect E Struct Rep Online 2014; 70:i47-i48. [PMID: 25309171 PMCID: PMC4186203 DOI: 10.1107/s1600536814016729] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Accepted: 07/18/2014] [Indexed: 11/12/2022]
Abstract
The title compound, tetrasodium cobalt(II) tris[molybdate(IV)], was prepared by solid-state reactions. The structure is isotypic with Na3In2(AsO4)3 and Na3In2(PO4)3. The main structural feature is the presence of infinite chains of edge-sharing X2O10 (X = Co/Na) dimers, which are linked by MoO4 tetrahedra, forming a three-dimensional framework enclosing two types of hexagonal tunnels in which Na+ cations reside. In this alluaudite structure, Co and Na atoms are located at the same general site with occupancies of 0.503 (5) and 0.497 (6), respectively. The other three Na and one of the two Mo atoms lie on special positions (site symmetries 2, -1, 2 and 2, respectively). The structure is compared with similar structures and other members of alluaudite family.
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The inhibitory effect of metals and other ions on acid phosphatase activity from Vigna aconitifolia seeds. Prep Biochem Biotechnol 2014; 45:33-41. [PMID: 24547935 DOI: 10.1080/10826068.2014.887578] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Sensitivity of acid phosphatase from Vigna aconitifolia seeds to metal ions, fluoride, and phosphate was examined. All the effectors had different degree of inhibitory effect on the enzyme. Among metal ions, molybdate and ferric ion were observed to be most potent inhibitors and both exhibited mixed type of inhibition. Acid phosphatase activity was inhibited by Cu2+ in a noncompetitive manner. Zn and Mn showed mild inhibition on the enzyme activity. Inhibition kinetics analysis explored molybdate as a potent inhibitor for acid phosphatase in comparison with other effectors used in this study. Fluoride was the next most strong inhibitor for the enzyme activity, and caused a mixed type of inhibition. Phosphate inhibited the enzyme competitively, which demonstrates that inhibition due to phosphate is one of the regulatory factors for enzyme activity.
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Sodium molybdate prevents hypertension and vascular prostanoid imbalance in fructose-overloaded rats. ACTA ACUST UNITED AC 2013; 33:43-8. [PMID: 23906370 DOI: 10.1111/aap.12010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 05/07/2013] [Indexed: 12/25/2022]
Abstract
(1) Fructose (F) overload produces elevated blood pressure (BP), hyperglycaemia, hypertriglyceridemia and insulin resistance, resembling human metabolic syndrome. Previously, we found altered vascular prostanoid (PR) production in this model. (2) Sodium molybdate (Mo), as well as sodium tungstate, causes insulin-like effects and normalizes plasma glucose levels in streptozotocin-treated diabetic rats. We studied the effects of Mo on BP, metabolic parameters and release of PR from the mesenteric vascular bed (MVB) in F-overloaded rats. (3) Four groups of male Sprague-Dawley rats were analysed: Control, tap water to drink; F, F solution 10% W/V to drink; CMo, Mo 100 mg kg day(-1) and FMo, both treatments. After 9 weeks, the animals were killed and MVBs removed and the released PRs measured. (4) F increased BP, glycemia, triglyceridemia and insulinemia. Mo treatment prevented the increases in BP and glycemia, but did not modify triglyceridemia or insulinemia. In addition, Mo decreased BP in controls. (5) Prostaglandins (PG) F2 alpha and E2, PG 6-ketoF1 alpha and thromboxane (TX) B2 , as well as inactive metabolites of prostacyclin (PGI2 ) and TXA2 were detected. F decreased the production of vasodilator PRs PGI2 and PGE2 in MVB. Mo prevented these alterations and increased PGE2 in controls. Vasoconstrict or PRs PGF2 alpha and TXA2 release was not modified. (6) Mo treatment, beyond its known lowering effect on glycemia, prevents the reduction in the vascular release of vasodilator PR observed in this model. This could be one of the mechanisms by which Mo avoids the increase in BP caused by F overload in the rat.
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Nitrogenase assembly. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1827:1112-22. [PMID: 23232096 DOI: 10.1016/j.bbabio.2012.12.001] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 12/02/2012] [Accepted: 12/03/2012] [Indexed: 11/18/2022]
Abstract
Nitrogenase contains two unique metalloclusters: the P-cluster and the M-cluster. The assembly processes of P- and M-clusters are arguably the most complicated processes in bioinorganic chemistry. There is considerable interest in decoding the biosynthetic mechanisms of the P- and M-clusters, because these clusters are not only biologically important, but also chemically unprecedented. Understanding the assembly mechanisms of these unique metalloclusters is crucial for understanding the structure-function relationship of nitrogenase. Here, we review the recent advances in this research area, with an emphasis on our work that provide important insights into the biosynthetic pathways of these high-nuclearity metal centers. This article is part of a Special Issue entitled: Metals in Bioenergetics and Biomimetics Systems.
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Apo and ligand-bound structures of ModA from the archaeon Methanosarcina acetivorans. Acta Crystallogr Sect F Struct Biol Cryst Commun 2010; 66:242-50. [PMID: 20208152 PMCID: PMC2833028 DOI: 10.1107/s1744309109055158] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Accepted: 12/22/2009] [Indexed: 11/10/2022]
Abstract
The trace-element oxyanion molybdate, which is required for the growth of many bacterial and archaeal species, is transported into the cell by an ATP-binding cassette (ABC) transporter superfamily uptake system called ModABC. ModABC consists of the ModA periplasmic solute-binding protein, the integral membrane-transport protein ModB and the ATP-binding and hydrolysis cassette protein ModC. In this study, X-ray crystal structures of ModA from the archaeon Methanosarcina acetivorans (MaModA) have been determined in the apoprotein conformation at 1.95 and 1.69 A resolution and in the molybdate-bound conformation at 2.25 and 2.45 A resolution. The overall domain structure of MaModA is similar to other ModA proteins in that it has a bilobal structure in which two mixed alpha/beta domains are linked by a hinge region. The apo MaModA is the first unliganded archaeal ModA structure to be determined: it exhibits a deep cleft between the two domains and confirms that upon binding ligand one domain is rotated towards the other by a hinge-bending motion, which is consistent with the 'Venus flytrap' model seen for bacterial-type periplasmic binding proteins. In contrast to the bacterial ModA structures, which have tetrahedral coordination of their metal substrates, molybdate-bound MaModA employs octahedral coordination of its substrate like other archaeal ModA proteins.
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