The Kinetics of Ion Association in Manganese Sulfate Solutions. I. Results in Water, Dioxane-Water Mixtures, and Methanol-Water Mixtures at 25°

Atkinson, Gordon; Kor, S. K.

doi:10.1021/j100885a020

Cited by 48 publications

(20 citation statements)

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“…2 The calculations use a computer program (Cohen and Colman, 1972) with values of 57.6 and 1150 M-1 for the association constants of manganous ion with dibasic and tribasic isocitrate (Grzybowski et al, 1970). Corrections were made for the association of manganous ions with chloride (Aa = 3.7 M-1) (Grzybowski et al, 1970), with acetate ions (Aa = 15.8 M_1) (Vallee and Wacker, 1970), with sulfate ions (A"a = 139 M-1) (Atkinson and Kor, 1965), and with Mes (Aa = 5 M_l) (Good et al, 1966). FIGURE 3: Lineweaver-Burk plots of the variation of the velocity of oxalosuccinate decarboxylation with manganous ion concentration in the presence and absence of coenzymes.…”

Section: Resultsmentioning

confidence: 99%

Influence of substrates and coenzymes on the role of manganous ion in reactions catalyzed by pig heart triphosphopyridine nucleotide-dependent isocitrate dehydrogenase

Ehrlich¹,

Colman²

1976

Biochemistry

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The interaction of manganous ions with pig heart triphosphopyridine nucleotide (TPN) specific isocitrate dehydrogenase has been studied by kinetic experiments and by direct ultrafiltration measurements of manganous ion binding. At low metal ion concentrations, a lag is observed in the time-dependent production of reduced triphosphopyridine nucleotide (TPNH) that can be eliminated by adding 20 muM TPNH to the initial reaction mixture. A plot of 1/upsilon vs. 1/ (Mn2+) obtained at relatively high TPNH concentrations (20 muM) is linear and yields of Km value of 2 muM for metal ion, which is comparable to the direct binding constant measured in the presence of isocitrate. A similar plot at low TPNH concentrations (2 muM) reveals a biphasic relationship: at high metal concentrations the points are collinear with those obtained at high levels of TPNH, but at low metal concentrations that line is characterized by a Km of 19 muM for Mn2+. A difference in the deuterium oxide solvent isotope effect on Vmax observed with 20 muM TPNH as compared with 2 muM TPNH suggests that at high TPNH concentrations or high manganous ion concentrations the rate-limiting step is the dehydrogenation of isocitrate, while at low manganous ion concentrations and low TPNH concentrations, the slow step is the decarboxylation of enzyme-bound oxalosuccinate. Evidence to support this hypothesis is provided by the sensitivity to isocitrate concentration of the Km for total manganese measured in the presence of 20 muM TPNH that contrasts with the relative insensitivity to isocitrate of the Km measured at 2 muM TPNH and low manganous ion concentration. Direct measurements of oxalosuccinate decarboxylation reveal that the Vmax and the Km for manganous ion are influenced by the presence of oxidized or reduced TPN with the Km being lowest (5-7 muM) in the presence of TPNH. The dependence of the Km for manganous ion on the presence of substrate, TPN, and TPNH, is responsible for the variation with conditions in the rate-determining step. The enzyme binds only 1 mol of metal ion and 1 mol of isocitrate/mol of protein under all conditions. The pH dependence of the binding of free manganous ion, free isocitrate, and manganous-isocitrate complex indicates differences in the interaction of these species with isocitrate dehydrogenase. These results can be described in terms of two functions for manganous ion in the reactions catalyzed by isocitrate dehydrogenase, each of which requires a distinct binding site for metal ion: in the dehydrogenation step, Mn2+ facilitates the binding of the substrate isocitrate, and in the decarboxylation step it may stabilize the enolate of alpha-ketoglutarate which is generated.

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Section: Resultsmentioning

confidence: 99%

Influence of substrates and coenzymes on the role of manganous ion in reactions catalyzed by pig heart triphosphopyridine nucleotide-dependent isocitrate dehydrogenase

Ehrlich¹,

Colman²

1976

Biochemistry

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“…[25] This has significant implications since it was then possible to determine the kinetics and the corresponding energies for the ion pairing process. [26][27][28] Since ILs and organic electrolytes tend to exhibit a markedly more diverse interaction landscape than the non-specific electrostatic interactions found in e. g. simple metal halide electrolytes, Hunt et al categorized interactions in ILs as Hbonds of three types. [29] The neutral H-bond X•••Y, the ionic Hbond [X] + ,À •••Y between an ion and a neutral molecule and the double ionic H-bond [X] + •••[Y] À between two ions.…”

Section: Introductionmentioning

confidence: 99%

“…Bjerrum further considered that ion pairs and free ions in solution will be in thermodynamic equilibrium and hence the law of mass action and an equilibrium association constant could be defined [25] . This has significant implications since it was then possible to determine the kinetics and the corresponding energies for the ion pairing process [26–28] …”

Section: Introductionmentioning

confidence: 99%

Solvation and Ion‐Pairing Effects of Choline Acetate Electrolyte in Protic and Aprotic Solvents Studied by NMR Titrations

et al. 2021

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Choline-based electrolytes have been proposed as environmentally friendly and low-cost alternatives for secondary zinc air batteries. Choline acetate [Ch] + [OAc] À in protic (D 2 O) and aprotic (DMSO-d 6 ) solvents has been studied by means of concentration-dependent 1 H NMR, viscosity, and density measurements. The viscosities have been calculated on the basis of the Jones-Dole equation and showed that the dominant contribution originates from short-range ion-solvent interactions. Site-specific association affinities were assigned from NMR chemical shift titrations. In DMSO-d 6 , the hydroxyl group of choline was found to have the smallest dissociation constant followed by the methyl group of acetate. The corresponding Gibbs energies at low concentration were found to be in agreement with a solvent-separated ion pair (2SIP) configuration, whereas at concentrations above 300 mM, a solventshared ion pair (SIP) configuration was assigned. For [Ch] + [OAc] À in D 2 O, association effects were found to be weaker, attributed to the high dielectric constant of the solvent. On time scales on the order of 100 ms, NMR linewidth perturbations indicated a change in the local rotational dynamics of the ions, attributed to short-range cation-solvent interactions and not to solvent viscosity. At 184 mM, �40 % of the cations in DMSO-d 6 and �10 % in D 2 O were found to exhibit short-range interactions, as indicated by the linewidth perturbations. It was found that at about 300 mM, the ions in DMSO-d 6 exhibit a transition from free to collective translational dynamics on time scales on the order of 400 ms. In DMSO-d 6 , both ions were found to be almost equally solvated, whereas in D 2 O solvation of acetate was stronger, as indicated by the obtained effective hydrodynamic radii. For [Ch] + [OAc] À in DMSO-d 6 , the results suggest a solvent-shared ion association with weak H-bonding interactions for concentrations between 0.3-1 M. Overall, the extent of ion association in solvents such as DMSO is not expected to significantly limit charge transport and hinder the performance of choline-based electrolytes.[a] E.

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“…Detailed studies (2)(3)(4)(5)(6) have since shown that the stepwise ion association in aqueous solutions of 2-2 electrolytes could account for the absorption in excess of that expected from viscous losses. The assignment of mechanism was aided by a study of mixed solvent solutions of these salts (7) ; there are, however, still some discrepancies in both the data and its interpretation (4)(5)(6). The low concentration of ion pairs in aqueous solutions of 1-1 electrolytes excludes their showing an excess absorption except at salt concentrations much higher than that found in sea water (8).…”

Section: Introductionmentioning

confidence: 99%

Ion Pair Formation in Solutions of Alkali Halides in Dimethyl Sulfoxide: Ultrasonic Absorption Studies

Dickson¹,

Kruus²

1971

Can. J. Chem.

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The ultrasonic absorption of dimethyl sulfoxide solutions of several alkali halides has been studied in the frequency range 1.5 to 52 MHz. An excess absorption, relaxing between 3 and 8 MHz, was observed. The relaxation was assigned to the final step in the stepwise formation of a contact ion pair, with the relaxation frequency controlled by the rate of movement of a solvent molecule rather than an ion. Data on the system water – dimethyl sulfoxide are also presented and the effect of water on the relaxation discussed.

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The Kinetics of Ion Association in Manganese Sulfate Solutions. I. Results in Water, Dioxane-Water Mixtures, and Methanol-Water Mixtures at 25°

Cited by 48 publications

References 2 publications

Influence of substrates and coenzymes on the role of manganous ion in reactions catalyzed by pig heart triphosphopyridine nucleotide-dependent isocitrate dehydrogenase

Influence of substrates and coenzymes on the role of manganous ion in reactions catalyzed by pig heart triphosphopyridine nucleotide-dependent isocitrate dehydrogenase

Solvation and Ion‐Pairing Effects of Choline Acetate Electrolyte in Protic and Aprotic Solvents Studied by NMR Titrations

Ion Pair Formation in Solutions of Alkali Halides in Dimethyl Sulfoxide: Ultrasonic Absorption Studies

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