Ion Chromatographic Study of Sulfate-Triethylenetetramine Complexes in Aqueous Solution

Nishimura, Masayuki; Hayashi, Morimasa; Hayakawa, Kazuichi; Miyazaki, Motoichi

doi:10.2116/analsci.10.321

Cited by 7 publications

(7 citation statements)

References 4 publications

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“…Some multivalent cations have been used as pairing ions in liquid chromatography for the separation of NDS isomers with polyethyleneammonium ions 14 and inorganic anions with triethylenetetramine 15 and hexamethonium has been used for the separation of metallo-cyanide complexes in CZE. 16 However, the analysis of ion association reactions in aqueous solution have not previously been studied with such cations.…”

Section: Separation Of Positional Isomers With Divalent Ammonium Ionsmentioning

confidence: 99%

Separation of Divalent Aromatic Anions by Capillary Zone Electrophoresis Using Multipoint Ion Association With Divalent Quaternary Ammonium Ions

Takayanagi¹,

Wada²,

Motomizu³

1997

Analyst

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Positional isomers of naphthalenedisulfonate (NDS), naphthalenedicarboxylate (NDC) and phthalate were separated using an ion association reaction in aqueous solution followed by capillary zone electrophoresis with a polymer coated capillary. By using divalent quaternary ammonium ions, four NDS isomers and three NDC isomers were completely resolved, although some of the isomers were not resolved with tetrabutylammonium ion. Ion association constants, K ass , between the anions and the divalent quaternary ammonium cations were also determined by analyzing the change in electrophoretic mobility using a non-linear least-squares method. The K ass values of the anions obtained with the divalent cations were larger than those with tetrabutylammonium ion because of an increased electrostatic interaction. The ion associability was also explained on the basis of a distance-fitting concept and the hydrophobicity concept of the pairing cations. Ion associability was also improved by using a better distance-fitting pairing ion. From the results obtained, it was suggested that the charge-charge distance in cationic and anionic molecules must be close, and the charge-charge distance of the divalent cations was about 0.2 nm longer than that of divalent anions for good ion associability (a distance-fitting concept).

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Section: Separation Of Positional Isomers With Divalent Ammonium Ionsmentioning

confidence: 99%

Separation of Divalent Aromatic Anions by Capillary Zone Electrophoresis Using Multipoint Ion Association With Divalent Quaternary Ammonium Ions

Takayanagi¹,

Wada²,

Motomizu³

1997

Analyst

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“…The net charge on GOx was gradually increased from −62 (pristine GOx at pH 7, pI 4.3) to +95 by reacting the −COOH residues of the enzyme with increasing amounts of TETA (10–30 mM), under specific conditions of pH, temperature, carbodiimide (EDC) concentration, and reaction time (Scheme ). Two of the four TETA nitrogens of the modified side chain (p K a values = 9.20 and 9.92) are expected to be protonated under these experimental conditions (pH 7). One nitrogen will contribute to the amide bond formation with the COOH group, and the p K a value of the fourth nitrogen is too low for protonation to occur.…”

Section: Resultsmentioning

confidence: 93%

“…Two of the four TETA nitrogens of the modified side chain (p K a values = 9.20 and 9.92) 41 are expected to be protonated under these experimental conditions (pH 7). One nitrogen will contribute to the amide bond formation with the COOH group, and the p K a value of the fourth nitrogen is too low for protonation to occur.…”

Section: Resultsmentioning

confidence: 93%

Tuning Enzyme/α-Zr(IV) Phosphate Nanoplate Interactions via Chemical Modification of Glucose Oxidase

et al. 2017

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Using glucose oxidase (GOx) and α-Zr(IV) phosphate nanoplates (α-ZrP) as a model system, a generally applicable approach to control enzyme–solid interactions via chemical modification of amino acid side chains of the enzyme is demonstrated. Net charge on GOx was systematically tuned by appending different amounts of polyamine to the protein surface to produce chemically modified GOx(n), where n is the net charge on the enzyme after the modification and ranged from −62 to +95 electrostatic units in the system. The binding of GOx(n) with α-ZrP nanosheets was studied by isothermal titration calorimetry (ITC) as well as by surface plasmon resonance (SPR) spectroscopy. Pristine GOx showed no affinity for the α-ZrP nanosheets, but GOx(n) where n ≥ −20 showed binding affinities exceeding (2.1 ± 0.6) × 106 M−1, resulting from the charge modification of the enzyme. A plot of GOx(n) charge vs Gibbs free energy of binding (ΔG) for n = +20 to n = +65 indicated an overall increase in favorable interaction between GOx(n) and α-ZrP nanosheets. However, ΔG is less dependent on the net charge for n > +45, as evidenced by the decrease in the slope as charge increased further. All modified enzyme samples and enzyme/α-ZrP complexes retained a significant amount of folding structure (examined by circular dichroism) as well as enzymatic activities. Thus, strong control over enzyme–nanosheet interactions via modulating the net charge of enzymes may find potential applications in biosensing and biocatalysis.

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“…An increased m / z from 142 896.3 Da (pristine GOx, Figure S3A) to 149 344.3 Da (GOx(+75), Figure S3B) was observed. Each TETA is expected to contribute a charge of +2 due to protonation of two nitrogens of TETA with p K a values of 9.20 and 9.92, and the fourth nitrogen has p K a < 7. One of the four nitrogens is used to form the amide bond, consuming a negatively charged carboxyl group.…”

Section: Resultsmentioning

confidence: 99%

Designer Histone Complexes: Controlling Protein–DNA Interactions with Protein Charge as an “All-or-None” Digital Switch

2016

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An artificial histone is synthesized that functions as a DNA-protein digital switch, where DNA binding is all or none, controlled by a sharp threshold of protein charge. A non-DNA-binding protein, glucose oxidase (GOx), was chemically modified by attaching an increasing number of triethylenetetramine (TETA) side chains to its glutamate/aspartate groups to obtain a small library of covalently modified GOx(n) derivatives. The parameter n denotes the net charge on the protein at pH 7, which was increased from -62 (pristine GOx) to +75 by attaching an increasing number of TETA residues to the protein. All GOx(n) derivatives retained their secondary structure to a good extent, as monitored by UV circular dichroism (CD) spectroscopy, and they also retained oxidase activities to a significant extent. The interaction of the GOx(n) with calf thymus DNA was examined by isothermal titration calorimetry (ITC). Pristine GOx of -62 charge at pH 7 in 10 mM Tris-HCl and 50 mM NaCl buffer had no affinity for the negatively charged DNA helix, and GOx(n) with n < +30 had no affinity for DNA either. However, binding has been turned on abruptly when n ≥ +30 with binding constants (K) ranging from (1.5 ± 0.7) × 10 to (7.3 ± 2.8) × 10 M for n values of +30 and +75, respectively, and this type of "all-or-none" binding based on protein charge is intriguing. Furthermore, thermodynamic analysis of the titration data revealed that binding is entirely entropy-driven with ΔS ranging from 0.09 ± 0.007 to 0.19 ± 0.008 kcal/mol K with enthalpic penalties of 17.0 ± 2.3 and 46.1 ± 2.1 kcal/mol, respectively. The binding had intrinsic propensities (ΔG) ranging from -9.8 ± 0.14 to -10.7 ± 0.25 kcal/mol, independent of n. DNA binding distorted protein-DNA secondary structure, as evidenced by CD spectroscopy, but oxidase activity of GOx(n)/DNA complexes has been unaffected. This is the very first example of an artificial histone (GOx(n)) where the protein charge functioned as a DNA-binding switch; protein charge is in turn under complete chemical control while preserving the biological activity of the protein. The new insight gained here could be useful in the design of novel "on-off" protein switches.

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Ion Chromatographic Study of Sulfate-Triethylenetetramine Complexes in Aqueous Solution

Cited by 7 publications

References 4 publications

Separation of Divalent Aromatic Anions by Capillary Zone Electrophoresis Using Multipoint Ion Association With Divalent Quaternary Ammonium Ions

Separation of Divalent Aromatic Anions by Capillary Zone Electrophoresis Using Multipoint Ion Association With Divalent Quaternary Ammonium Ions

Tuning Enzyme/α-Zr(IV) Phosphate Nanoplate Interactions via Chemical Modification of Glucose Oxidase

Designer Histone Complexes: Controlling Protein–DNA Interactions with Protein Charge as an “All-or-None” Digital Switch

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