Interactions of divalent metal ions with inorganic and nucleoside phosphates.4-II. Kinetics of magnesium(II) with HP3O10, ATP, CTP, HP2O73-, ADP, CDP

Frey, Cheryl Miller; Banyasz, Joseph L.; Stuehr, J. E.

doi:10.1021/ja00781a035

Cited by 45 publications

(17 citation statements)

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“…(5) (K 4 = 537 M -1) whereas at pH 8 there are two inflection points, corresponding to the consecutive equilibria depicted by Eqs (7) and (8) are in good agreement with values reported in the literature [7,9,14,35,36].…”

Section: Influence Of Ph On Complexation Constantsupporting

confidence: 89%

Capillary electrophoretic study of the complexation of nucleotides with magnesium and calcium ions

1998

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SummaryThe complexation equilibrium between nucleotides (ATP, ADP) and inorganic cations (Mg 2+, Ca 2+) has been studied by capillary electrophoresis. The equilibrium constant and the stoichiometry of nucleotideinorganic cation complexes can be deduced from the dependence of the electrophoretic mobility of each nucleotide on the negative logarithm of the inorganic cation concentration. The experimental values of complexation constants determined by CE compare favorably with those in the literature. As expected, Mg 2+ forms more stable complexes with ATP (log K = 2.30 and 4.10 at pH 5 and 8, respectively) than with ADP (log K = 1.92 and 3.15 at pH 5 and 8, respectively). In the pH range 4-8, the stoichiometry of ADP-Mg 2+ and ADP-Ca 2+ complexes is always 1:1 whereas that of the complexes between these cations and ATP depends on pH -hence ATP-Mg 2+ and ATP-Ca 2+ complexes have 1:1 stoichiometry at pH 5 and 1:2 at pH 8.

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Section: Influence Of Ph On Complexation Constantsupporting

confidence: 89%

Capillary electrophoretic study of the complexation of nucleotides with magnesium and calcium ions

1998

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“…A mixture of reduced Ac2 protein (404uM) and Acl protein (Il5pM) in 25nM-Tris/HCI buffer, pH7.4, containing lOmM-Na2S204 and IOmM-MgC92 was mixed in the stopped-flow apparatus with a series of solutions containing 5.-O.2nIM-ATP. An increase in E425 occurred in a single exponential process, and the associated time-constants (r) were determined at various MgATP concentrations (calculated by using KMgATP = 1.12x 104M-1 and KMg ATP = 59M-1; Frey et al, 1972). A plot of r versus (MgATP]-1 ( Fig.…”

Section: Rate Of Oxidation Of Ac2 Protein By Acl Protein Induced By Mmentioning

confidence: 99%

Nitrogenase of Azotobacter chroococcum. Kinetics of the reduction of oxidized iron-protein by sodium dithionite

Thorneley

Yates

Lowe

1976

Biochemical Journal

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The kinetics of the reduction of oxidized Fe-protein of nitrogenase from Azotobacter chroococcum by sodium dithionite were studied by stopped-flow and rapid-freezing e.p.r. (electron-paramagnetic-resonance) spectroscopy. The appearance of the gav. = 1.94 e.p.r. signal (0.24 electron integrated intensity/mol) was associated with a one-electron reduction by SO2--with k greater than 10(8)M-1-S-1 at 23 degrees C. A value of k = 1.75s-1 was obtained for the rate of dissociation of S2O42- into 2SO2-- at 23 degrees C. Further reductions by SO2-- occurred in three slower phases with rate constants in the range 10(4) -10(6)M-1-S-1. These latter phases have no corresponding e.p.r. signal changes and are probably associated with enzymically inactive protein. The high rate of reduction by SO2-- of the Fe-protein alone (k greater than 10(8)M-1-S-1) relative to the rate of oxidation of the Fe-protein in the catalytically active Fe:Mo-Fe protein complex (k = 2.2 X 1O(2)s-1) and the observation that in the steady state the Fe-protein is substantially oxidized means that at normal assay concentrations another reaction must limit the rate of reduction of Fe-protein during turnover.

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“…Although much of what is currently known about metal homeostasis involves their interaction with proteins and other organic macromolecules, metal cations can also bind small negatively charged inorganic compounds, such as phosphate. Phosphate readily forms complexes in vitro with a wide range of metals [1]. In some instances, such interactions can alter the reactivity of the cation, particularly redox active transition metals [2, 3].…”

Section: Introductionmentioning

confidence: 99%

The effect of phosphate accumulation on metal ion homeostasis in Saccharomyces cerevisiae

et al. 2010

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Much of what is currently understood about the cell biology of metals involves their interactions with proteins. By comparison, little is known about metal interactions with intracellular inorganic compounds such as phosphate. Here we examined the role of phosphate in metal metabolism in vivo by genetically perturbing the phosphate content of Saccharomyces cerevisiae cells. Yeast pho80 mutants cannot sense phosphate and have lost control of phosphate uptake, storage and metabolism. We report here that pho80 mutants specifically elevate cytosolic and non-vacuolar phosphate and this in turn causes a wide range of metal homeostasis defects. Intracellular levels of the hard metal cations sodium and calcium increase dramatically, and cells become susceptible to toxicity from the transition metals manganese, cobalt, zinc and copper. Disruptions in phosphate control also elicit an iron starvation response, as pho80 mutants were seen to up-regulate iron transport genes. The iron responsive transcription factor Aft1p appears activated in cells with high phosphate in spite of normal intracellular iron levels. The high phosphate of pho80 mutants can be lowered by mutating Pho4p, the transcription factor for phosphate uptake and storage genes. Such lowering of phosphate by pho4 mutations reversed the high calcium and sodium of pho80 mutants and prevented the iron starvation response. However, pho4 mutations only partially reversed toxicity from heavy metals, representing a novel outcome of phosphate dysregulation. Overall these studies underscore the importance of maintaining a charge balance in the cell; a disruption in phosphate metabolism can dramatically impact on metal homeostasis.

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Interactions of divalent metal ions with inorganic and nucleoside phosphates.4-II. Kinetics of magnesium(II) with HP3O10, ATP, CTP, HP2O73-, ADP, CDP

Cited by 45 publications

References 0 publications

Capillary electrophoretic study of the complexation of nucleotides with magnesium and calcium ions

Capillary electrophoretic study of the complexation of nucleotides with magnesium and calcium ions

Nitrogenase of Azotobacter chroococcum. Kinetics of the reduction of oxidized iron-protein by sodium dithionite

The effect of phosphate accumulation on metal ion homeostasis in Saccharomyces cerevisiae

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