Binding studies using ion-selective electrodes.  Examination of the picrate-albumin interaction as a model system

Christopoulos, Theodore K.; Diamandis, Eleftherios P.

doi:10.1021/ac00203a010

Cited by 17 publications

(8 citation statements)

References 31 publications

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“…For this purpose, a modification of the potentiometric ion-probe technique (Angelakou et al 1994) was applied for continuous monitoring of the free drug ion in the reaction mixture of protein-drug-toxin by direct potentiometry. The big advantage of ion selective electrode (ISE) direct potentiometry, when applied to protein binding studies, is its ability to measure directly the activity of the free drug anion in diluted and concentrated protein solutions and in undiluted biological specimens, thus overcoming the dilution step, which is the major drawback of spectroscopic techniques (Christopoulos & Diamandis 1990;Valsami et al 1991;Angelakou et al 1994Angelakou et al , 1999Sideris et al 1994).…”

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confidence: 99%

In-vitro study on the competitive binding of diflunisal and uraemic toxins to serum albumin and human plasma using a potentiometric ion-probe technique

Davilas

Koupparis

Macheras

et al. 2006

Journal of Pharmacy and Pharmacology

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The competitive binding of diflunisal and three well-known uraemic toxins (3-indoxyl sulfate, indole-3-acetic acid and hippuric acid) to bovine serum albumin (BSA), human serum albumin (HSA) and human plasma was studied by direct potentiometry. The method used the potentiometric drug ion-probe technique with a home-made ion sensor (electrode) selective to the drug anion. The site-oriented Scatchard model was used to describe the binding of diflunisal to BSA, HSA and human plasma, while the general competitive binding model was used to calculate the binding parameters of the three uraemic toxins to BSA. Diflunisal binding parameters, number of binding sites, n(i) and association constants for each class of binding site, K(i), were calculated in the absence and presence of uraemic toxins. Although diflunisal exhibits high binding affinity for site I of HSA and the three uraemic toxins bind primarily to site II, strong interaction was observed between the drug and the three toxins, which were found to affect the binding of diflunisal on its primary class of binding sites on both BSA and HSA molecules and on human plasma. These results are strong evidence that the decreased binding of diflunisal that occurs in uraemic plasma may not be solely attributed to the lower albumin concentration observed in many patients with renal failure. The uraemic toxins that accumulate in uraemic plasma may displace the drug from its specific binding sites on plasma proteins, resulting in increased free drug plasma concentration in uraemic patients.

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confidence: 99%

In-vitro study on the competitive binding of diflunisal and uraemic toxins to serum albumin and human plasma using a potentiometric ion-probe technique

Davilas

Koupparis

Macheras

et al. 2006

Journal of Pharmacy and Pharmacology

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“…The potential values E, were plotted against the negative logarithm of the ANS concentration, to give the calibration (response) curve of the ISE, using a least squares linear fitting program. Corrections for the change in volume after addition were performed by the program utilized for the analysis of data (Christopoulos & Diamandis 1990;Valsami et a1 1991). The construction of the calibration curve is necessary on each working day.…”

Section: Reagentsmentioning

confidence: 99%

“…By using these mixed titrant solutions, the BSA and the sulphonamide concentrations remain constant during the binding experiment, making the data analysis simpler. In the case of plasma, corrections for the dilution after each addition were performed by the program (Christopoulos & Diamandis 1990;Valsami et al 1991).…”

Section: Reagentsmentioning

confidence: 99%

“…The parameters n, or N,, K, or (KJapp, for all sets of experiments, were calculated by a nonlinear least-squares method of performing fitting of equations 1 and 2 to the experimental data (potential readings Etotal ANS concentration T) (Christopoulos & Diamandis 1990;Valsami et a1 1991).…”

Section: Reagentsmentioning

confidence: 99%

“…Such ,a dilution causes disturbance of equilibrium conditions. In recent years, a novel direct technique devoid of this drawback using potentiometry with ion-selective electrodes (ISEs) has been developed and applied to binding studies (Takisawa et a1 1988;Christopoulos & Diamandis 1990;Valsami et a1 1990Valsami et a1 , 1991Valsami et a1 , 1992.…”

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confidence: 99%

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Use of 1-Anilino-8-napthalenesulphonate as an Ion Probe for the Potentiometric Study of the Binding of Sulphonamides to Bovine Serum Albumin and Plasma

Angelakou

Valsami

Koupparis

et al. 1993

Journal of Pharmacy and Pharmacology

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The binding of sulphafurazole, sulphamethizole and sulphamethoxazole to bovine serum albumin (BSA) and human plasma has been studied in-vitro by potentiometry using an electrode selective for the ion probe 1-anilino-8-napthalenesulphonate (ANS). The method requires two separate potentiometric titrations of the binder solution with ANS in the absence and in the presence of sulphonamides. ANS displaced sulphonamides from the first-class of binding sites of both binders. The binding constants for sulphonamide-BSA interactions were higher than those for sulphonamide-human plasma. The expansion of the least linear limit of the response curve of the electrode down to 10(-7) M in the presence of BSA was also demonstrated. The reverse reaction, i.e. the displacement of the probe from the binding sites induced by the sulphonamides, was also explored. The proposed method is suitable for studying competitive binding interactions in biological specimens.

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Direct potentiometric membrane electrode measurements of heparin binding to macromolecules

Yun

‐C

et al. 1993

Electroanalysis

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The use of a newly developed heparin responsive polymeric membrane electrode for directly monitoring the binding of heparin to a variety of other biological macromolecules is examined. Potentiometric titrations of protamine, low-density lipoprotein (LDL), polybrene, DNase enzyme, and polylysine with either porcine or beef lung heparin can be followed conveniently by the electrode at various solution pHs. Such titrations yield endpoints that are used to determine the stoichiometry for the interaction of the different heparins with these macromolecules. Based on prior heparin calibration curves, the titration data can be recast in Scatchard form to obtain binding constants for these solutionphase heparin-macromolecular reactions. The speed and simplicity of the proposed method make it an attractive alternative to classical solid-phase binding methods or newer homogeneous fluorescent polarization schemes for studying the solution-phase interaction of heparin with other macromolecules.

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Binding studies using ion-selective electrodes. Examination of the picrate-albumin interaction as a model system

Cited by 17 publications

References 31 publications

In-vitro study on the competitive binding of diflunisal and uraemic toxins to serum albumin and human plasma using a potentiometric ion-probe technique

In-vitro study on the competitive binding of diflunisal and uraemic toxins to serum albumin and human plasma using a potentiometric ion-probe technique

Use of 1-Anilino-8-napthalenesulphonate as an Ion Probe for the Potentiometric Study of the Binding of Sulphonamides to Bovine Serum Albumin and Plasma

Direct potentiometric membrane electrode measurements of heparin binding to macromolecules

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