Speciation in Vanadium Bioinorganic Systems. 2. An NMR, ESR, and Potentiometric Study of the Aqueous H<sup>+</sup>−Vanadate−Maltol System

The general affinity of the sarcoplasmic reticulum (SR) Ca 2+ -ATPase was examined for three different classes of vanadium coordination complexes including a vanadium(V) compound, pyridine-2,6-dicarboxylatodioxovanadium(V) (PDC-V(V)), and two vanadium(IV) compounds, bis(maltolato)oxovanadium(IV) (BMOV), and an analogue of amavadine, bis(N-hydroxylamidoiminodiacetato)vanadium(IV) (HAIDA-V(IV)). The ability of vanadate to act either as a phosphate analogue or as a transition-state analogue with enzymes' catalysis phosphoryl group transfer suggests that vanadium coordination compounds may reveal mechanistic preferences in these classes of enzymes. Two of these compounds investigated, PDC-V(V) and BMOV, were hydrolytically and oxidatively reactive at neutral pH, and one, HAIDA-V(IV), does not hydrolyze, oxidize, or otherwise decompose to a measurable extent during the enzyme assay. The SR Ca 2+ -ATPase was inhibited by all three of these complexes. The relative order of inhibition was PDC-V(V) > BMOV > vanadate > HAIDA-V(IV), and the IC 50 values were 25, 40, 80, and 325 µM, respectively. Because the observed inhibition is more potent for PDC-V(V) and BMOV than that of oxovanadates, the inhibition cannot be explained by oxovanadate formation during enzyme assays. Furthermore, the hydrolytically and redox stable amavadine analogue HAIDA-V(IV) inhibited the Ca 2+ -ATPase less than oxovanadates. To gauge the importance of the lipid environment, studies of oxidized BMOV in microemulsions were performed and showed that this system remained in the aqueous pool even though PDC-V(V) is able to penetrate lipid interfaces. These findings suggest that the hydrolytic properties of these complexes may be important in the inhibition of the calcium pump. Our results show that two simple coordination complexes with known insulin enhancing effects can invoke a response in calcium homeostasis and the regulation of muscle contraction through the SR Ca 2+ -ATPase.

show abstract

“…40, 53 The oxidation of BMOV under the assay conditions described in this work immediately result in the formation of [VO 2 (ma) 2 ]…”

Section: Resultsmentioning

confidence: 89%

Sarcoplasmic Reticulum Calcium ATPase Is Inhibited by Organic Vanadium Coordination Compounds: Pyridine-2,6-dicarboxylatodioxovanadium(V), BMOV, and an Amavadine Analogue

et al. 2008

View full text Add to dashboard Cite

show abstract

“…All calculations were performed with SUPERQUAD [6], using published values for the equilibria of V(V) [7] in water and the acidity constants of Hdmpp [8]. The stability constants obtained for the vanadate/Hdmpp system are shown in Table 1 complexes.…”

Section: Potentiometrymentioning

confidence: 99%

Structural study of the interaction of vanadate with the ligand 1,2-dimethyl-3-hydroxy-4-pyridinone (Hdmpp) in aqueous solution

Castro

Geraldes

Gameiro

et al. 2000

Journal of Inorganic Biochemistry

View full text Add to dashboard Cite

The interaction of vanadate with the ligand 1,2-dimethyl-3-hydroxy-4-pyridinone (Hdmpp) was studied in aqueous solution using a combination of multinuclear NMR and EPR spectroscopies, as well as potentiometry and cyclic voltammetry. The different species in solution were identified and characterized, and their pK a values and stability constants determined. The vanadium complexes formed in solution are strongly dependent on media composition (ionic strength, presence of buffer), pH and metal-to-ligand ratio (M:L). Two major species -V(V)/dmpp and V(V)/(dmpp) 2 -are formed in a 140 mM NaCl solution within the pH range 4.5 to 9.0, when M:Ls1:2. In the presence of excess ligand (M:LF1:5), only the 1:2 complex is present, and at pH-4 paramagnetic species are detected by EPR in solution, thus indicating a reducing capacity of the ligand. Cyclic voltammetry shows that redox processes in solution are not just electron transfer, but are accompanied by chemical reactions. The pK a values and stability constants were determined both by 51 V NMR spectroscopy and potentiometry. The present results have a particular interest in the understanding of the aqueous solution chemistry in aerobic conditions of bis(1,2-dimethyl-3-hydroxy-4-pyridinonato) oxovanadium(IV) complex, VO(dmpp) 2 , a vanadium compound with potential insulin-mimetic properties. q2000 Elsevier Science Inc. All rights reserved.

show abstract

“…Polyoxovanadates larger than the pentameric species, other than decavanadates, have not been found to any great extent in aqueous solution [18]. , in which the oxygen is double-bonded [19].…”

Section: Introductionmentioning

confidence: 99%

Hetero and lacunary polyoxovanadate chemistry: Synthesis, reactivity and structural aspects

Hayashi

2011

Coordination Chemistry Reviews

213

126

View full text Add to dashboard Cite

Many synthetic methods for heteropolyoxovanadates and lacunary polyoxovanadates have been developed in recent years. We outline various approaches used to produce new polyoxovanadate species, including heterometal-incorporated complexes of tetravanadates, hexavanadates, decavanadates and dodecavanadates. In particular, three types of synthetic routes are explored; based on i) coordination of metavanadate species to transition metal cations, ii) oxidation of reduced polyoxovanadates, and iii) template synthesis. Metavanadate species can coordinate to metal cations as inorganic macrocyclic ligands to form heteropolyoxovanadates. The incorporation of a heterometal cation into decavanadates has also been reported. The oxidation reaction of reduced polyoxovanadates provides a new route to the formation of the lacunary polyoxovanadates, which can serve as inorganic host molecules. Dodecavanadates are bowl-type molecules of particular structural interest; a chloride anion can be incorporated into the bowl through a template synthesis. Structural transformations between these dodecavanadate species and alkoxopolyoxovanadates are also described.

show abstract

Speciation in Vanadium Bioinorganic Systems. 2. An NMR, ESR, and Potentiometric Study of the Aqueous H⁺−Vanadate−Maltol System

Cited by 106 publications

References 18 publications

Sarcoplasmic Reticulum Calcium ATPase Is Inhibited by Organic Vanadium Coordination Compounds: Pyridine-2,6-dicarboxylatodioxovanadium(V), BMOV, and an Amavadine Analogue

Sarcoplasmic Reticulum Calcium ATPase Is Inhibited by Organic Vanadium Coordination Compounds: Pyridine-2,6-dicarboxylatodioxovanadium(V), BMOV, and an Amavadine Analogue

Structural study of the interaction of vanadate with the ligand 1,2-dimethyl-3-hydroxy-4-pyridinone (Hdmpp) in aqueous solution

Hetero and lacunary polyoxovanadate chemistry: Synthesis, reactivity and structural aspects

Contact Info

Product

Resources

About

Speciation in Vanadium Bioinorganic Systems. 2. An NMR, ESR, and Potentiometric Study of the Aqueous H+−Vanadate−Maltol System

Cited by 106 publications

References 18 publications

Sarcoplasmic Reticulum Calcium ATPase Is Inhibited by Organic Vanadium Coordination Compounds: Pyridine-2,6-dicarboxylatodioxovanadium(V), BMOV, and an Amavadine Analogue

Sarcoplasmic Reticulum Calcium ATPase Is Inhibited by Organic Vanadium Coordination Compounds: Pyridine-2,6-dicarboxylatodioxovanadium(V), BMOV, and an Amavadine Analogue

Structural study of the interaction of vanadate with the ligand 1,2-dimethyl-3-hydroxy-4-pyridinone (Hdmpp) in aqueous solution

Hetero and lacunary polyoxovanadate chemistry: Synthesis, reactivity and structural aspects

Contact Info

Product

Resources

About

Speciation in Vanadium Bioinorganic Systems. 2. An NMR, ESR, and Potentiometric Study of the Aqueous H⁺−Vanadate−Maltol System