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Štěpánová S, Kašička V. Determination of physicochemical parameters of (bio)molecules and (bio)particles by capillary electromigration methods. J Sep Sci 2024; 47:e2400174. [PMID: 38867483 DOI: 10.1002/jssc.202400174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 05/03/2024] [Accepted: 05/10/2024] [Indexed: 06/14/2024]
Abstract
The review provides an overview of recent developments and applications of capillary electromigration (CE) methods for the determination of important physicochemical parameters of various (bio)molecules and (bio)particles. These parameters include actual and limiting (absolute) ionic mobilities, effective electrophoretic mobilities, effective charges, isoelectric points, electrokinetic potentials, hydrodynamic radii, diffusion coefficients, relative molecular masses, acidity (ionization) constants, binding constants and stoichiometry of (bio)molecular complexes, changes of Gibbs free energy, enthalpy and entropy and rate constants of chemical reactions and interactions, retention factors and partition and distribution coefficients. For the determination of these parameters, the following CE methods are employed: zone electrophoresis in a free solution or in sieving media, isotachophoresis, isoelectric focusing, affinity electrophoresis, electrokinetic chromatography, and electrochromatography. In the individual sections, the procedures for the determination of the above parameters by the particular CE methods are described.
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Affiliation(s)
- Sille Štěpánová
- Electromigration methods, Institute of Organic Chemistry and Biochemistry, The Czech Academy of Sciences, Prague, Czech Republic
| | - Václav Kašička
- Electromigration methods, Institute of Organic Chemistry and Biochemistry, The Czech Academy of Sciences, Prague, Czech Republic
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2
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Štěpánová S, Andris E, Gutten O, Buděšínský M, Dejmek M, Břehová P, Rulíšek L, Kašička V. Acidity constants and protonation sites of cyclic dinucleotides determined by capillary electrophoresis, quantum chemical calculations, and NMR spectroscopy. Electrophoresis 2024; 45:687-705. [PMID: 38059733 DOI: 10.1002/elps.202300232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Revised: 11/11/2023] [Accepted: 11/18/2023] [Indexed: 12/08/2023]
Abstract
Cyclic dinucleotides (CDNs) are important second messengers in bacteria and eukaryotes. Detailed characterization of their physicochemical properties is a prerequisite for understanding their biological functions. Herein, we examine acid-base and electromigration properties of selected CDNs employing capillary electrophoresis (CE), density functional theory (DFT), and nuclear magnetic resonance (NMR) spectroscopy to provide benchmark pKa values, as well as to unambiguously determine the protonation sites. Acidity constants (pKa) of the NH+ moieties of adenine and guanine bases and actual and limiting ionic mobilities of CDNs were determined by nonlinear regression analysis of the pH dependence of their effective electrophoretic mobilities measured by CE in aqueous background electrolytes in a wide pH range (0.98-11.48), at constant temperature (25°C), and constant ionic strength (25 mM). The thermodynamic pKa values were found to be in the range 3.31-4.56 for adenine and 2.28-3.61 for guanine bases, whereas the pKa of enol group of guanine base was in the range 10.21-10.40. Except for systematic shifts of ∼2 pKa, the pKa values calculated by the DFT-D3//COSMO-RS composite protocol that included large-scale conformational sampling and "cross-morphing" were in a relatively good agreement with the pKas determined by CE and predict N1 atom of adenine and N7 atom of guanine as the protonation sites. The protonation of the N1 atom of adenine and N7 atom of guanine in acidic background electrolytes (BGEs) and the dissociation of the enol group of guanine in alkaline BGEs was confirmed also by NMR spectroscopy.
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Affiliation(s)
- Sille Štěpánová
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czech Republic
| | - Erik Andris
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czech Republic
| | - Ondrej Gutten
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czech Republic
| | - Miloš Buděšínský
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czech Republic
| | - Milan Dejmek
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czech Republic
| | - Petra Břehová
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czech Republic
| | - Lubomír Rulíšek
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czech Republic
| | - Václav Kašička
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czech Republic
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Hajduk A, Ulrich N. Determination of acidity constants of pyridines, imidazoles, and oximes by capillary electrophoresis. Electrophoresis 2023; 44:1353-1360. [PMID: 37377077 DOI: 10.1002/elps.202300037] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 06/11/2023] [Accepted: 06/12/2023] [Indexed: 06/29/2023]
Abstract
The acidity constant in the form of pKa is one of the most important physicochemical quantities. There are prediction tools available for calculating the pKa , but they only deliver precise calculated values for a relatively small set of chemicals. For complex structures with multiple functional groups in particular, the error in the predicted pKa is high due to the application domain of the corresponding models. Thus, we aim to enlarge the dataset of experimentally determined pKa values using capillary electrophoresis. We, therefore, selected various pyridines, imidazoles, and oximes to determine the pKa values using the internal standard approach and the classical method. Especially oximes were not investigated in the past, and predictions for them include larger errors. Thus, our experimentally determined values could contribute to an improved understanding of various functional groups impacting the pKa values and serve as additional datasets to develop improved pKa prediction tools.
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Affiliation(s)
- Anna Hajduk
- Department of Ecological Chemistry, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Nadin Ulrich
- Department of Ecological Chemistry, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
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Han GE, Priefer R. A systematic review of various pK a determination techniques. Int J Pharm 2023; 635:122783. [PMID: 36858133 DOI: 10.1016/j.ijpharm.2023.122783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Revised: 02/19/2023] [Accepted: 02/23/2023] [Indexed: 03/02/2023]
Abstract
The pKa values of functional groups is crucial in determining the pharmacokinetic properties of a drug, affecting its absorption and thus bioavailability. This physicochemical property is also vital for the designing of drug excipients and vehicles. There are currently 13 known methods of determining a pKa value, namely: potentiometric titration, spectrometry, fluorometry, NMR, HPLC, conductometry, electrophoresis, voltammetry, solubility, partition coefficient, calorimetry, computational, and surface tension. Some of these techniques are more widely utilized and well-established compared to others, with each having their inherent advantages and disadvantages. This review discusses each of the aforementioned techniques with emphasis on their pros and cons.
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Affiliation(s)
- Gi Eun Han
- Massachusetts College of Pharmacy and Health Sciences, Boston, MA, United States
| | - Ronny Priefer
- Massachusetts College of Pharmacy and Health Sciences, Boston, MA, United States.
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Jin M, Kim J, Ha J, Kim A, Lee J, Park CS, Kang M, Kim J, Mun C, Kim J, Kim HH. Identification and quantification of sialylated and core-fucosylated N-glycans in human transferrin by UPLC and LC-MS/MS. Anal Biochem 2022; 647:114650. [PMID: 35331694 DOI: 10.1016/j.ab.2022.114650] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 01/26/2022] [Accepted: 03/09/2022] [Indexed: 11/01/2022]
Abstract
Sialylated and core-fucosylated N-glycans in human transferrin (HTF) are used as glycan biomarkers due to their increased or decreased characteristics in certain diseases. However, their absolute quantities remain unclear. In this study, N-glycans of HTF were identified by UPLC and LC-MS/MS using fluorescence tags [2-aminobenzamide (AB) and procainamide (ProA)] and columns [HILIC and anion exchange chromatography-HILIC (AXH)]. The structures of 14 (including five core-fucosylated) N-glycans in total comprising two non-, six mono-, four di-, and two tri-sialylated N-glycans were identified. The quantities (%) of each N-glycan relative to the total N-glycans (100%) were obtained. HILIC and AXH were better for peak identification and separability except for desialylation, respectively. Specifically, sialylated (in ProA-HILIC and ProA-AXH by UPLC or LC-MS/MS) and core-fucosylated (in AB-HILIC and ProA-AXH by UPLC) N-glycans were efficiently identified. Seven neuraminidase-treated (including three core-fucosylated) N-glycans were efficiently identified in ProA-AXH, even their poor separation. Additionally, ProA-AXH was more efficient for the estimation of the absolute quantities of N-glycans from the results of fluorescence intensity (by UPLC) and relative quantity (by LC-MS/MS). These results first demonstrate that ProA is useful for identifying and quantifying sialylated, core-fucosylated, and neuraminidase-treated desialylated N-glycans in HTF using AXH by UPLC and LC/MS.
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Affiliation(s)
- Mijung Jin
- Biotherapeutics and Glycomics Laboratory, College of Pharmacy, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea; Department of Global Innovative Drugs, Graduate School of Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Jihye Kim
- Biotherapeutics and Glycomics Laboratory, College of Pharmacy, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Jongkwan Ha
- Biotherapeutics and Glycomics Laboratory, College of Pharmacy, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Ahyeon Kim
- Biotherapeutics and Glycomics Laboratory, College of Pharmacy, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea; Department of Global Innovative Drugs, Graduate School of Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Jaeryong Lee
- Biotherapeutics and Glycomics Laboratory, College of Pharmacy, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea; Department of Global Innovative Drugs, Graduate School of Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Chi Soo Park
- Biotherapeutics and Glycomics Laboratory, College of Pharmacy, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea; Department of Global Innovative Drugs, Graduate School of Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Minju Kang
- Biotherapeutics and Glycomics Laboratory, College of Pharmacy, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea; Department of Global Innovative Drugs, Graduate School of Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Jeongeun Kim
- Biotherapeutics and Glycomics Laboratory, College of Pharmacy, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea; Department of Global Innovative Drugs, Graduate School of Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Chulmin Mun
- Biotherapeutics and Glycomics Laboratory, College of Pharmacy, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea; Department of Global Innovative Drugs, Graduate School of Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Jieun Kim
- Biotherapeutics and Glycomics Laboratory, College of Pharmacy, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea; Department of Global Innovative Drugs, Graduate School of Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Ha Hyung Kim
- Biotherapeutics and Glycomics Laboratory, College of Pharmacy, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea; Department of Global Innovative Drugs, Graduate School of Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea.
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Šolínová V, Štěpánová S, Jančařík A, Klívar J, Šámal M, Stará IG, Chocholoušová JV, Vacek J, Starý I, Kašička V. Nonaqueous capillary electrophoresis and quantum chemical calculations applied to investigation of acid-base and electromigration properties of azahelicenes. Electrophoresis 2021; 43:696-707. [PMID: 34933403 DOI: 10.1002/elps.202100331] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 12/06/2021] [Accepted: 12/16/2021] [Indexed: 11/07/2022]
Abstract
Nonaqueous capillary electrophoresis (NACE) using methanol (MeOH) as a solvent of the BGEs and quantum mechanical density functional theory (DFT) have been applied to determine the thermodynamic acidity (ionization) constants (pKa ) of mono- and diaza[5]helicenes, mono- and diaza[6]helicenes, and their dibenzo derivatives in MeOH and water. First, the mixed acidity constants, p K a , MeOH mix , of ionogenic pyridinium groups of azahelicenes and their derivatives in MeOH were obtained by nonlinear regression analysis of pH dependence of their effective electrophoretic mobilities. The effective mobilities were measured by NACE in a large series of methanolic BGEs within a wide conventional pH range (pHMeOH 1.6-12.0) and at ambient temperature (21-26°C) in a home-made CE device. Prior to mixed acidity constant calculation, the effective mobilities were corrected to reference temperature (25°C) and constant ionic strength (25 mM). Then, the mixed acidity constants were recalculated to the thermodynamic acidity constants pKa,MeOH by the Debye-Hückel theory of nonideality of electrolyte solutions. Finally, from the methanolic thermodynamic pKa,MeOH values, the aqueous thermodynamic p K a , H 2 O constants were estimated using the empirical relations between methanolic and aqueous acidity constants derived for structurally related pyridine derivatives. Depending on the number and position of the nitrogen atoms in their molecules, the analyzed azahelicenes were found to be weak to moderate bases with methanolic pKa,MeOH in the range 2.01-8.75 and with aqueous p K a , H 2 O in the range 1.67-8.28. The thermodynamic pKa,MeOH obtained by the DFT calculations were in a good agreement with those determined experimentally by NACE.
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Affiliation(s)
- Veronika Šolínová
- Institute of Organic Chemistry and Biochemistry, The Czech Academy of Sciences, Czech Republic
| | - Sille Štěpánová
- Institute of Organic Chemistry and Biochemistry, The Czech Academy of Sciences, Czech Republic
| | - Andrej Jančařík
- Institute of Organic Chemistry and Biochemistry, The Czech Academy of Sciences, Czech Republic
| | - Jiří Klívar
- Institute of Organic Chemistry and Biochemistry, The Czech Academy of Sciences, Czech Republic
| | - Michal Šámal
- Institute of Organic Chemistry and Biochemistry, The Czech Academy of Sciences, Czech Republic
| | - Irena G Stará
- Institute of Organic Chemistry and Biochemistry, The Czech Academy of Sciences, Czech Republic
| | | | - Jaroslav Vacek
- Institute of Organic Chemistry and Biochemistry, The Czech Academy of Sciences, Czech Republic
| | - Ivo Starý
- Institute of Organic Chemistry and Biochemistry, The Czech Academy of Sciences, Czech Republic
| | - Václav Kašička
- Institute of Organic Chemistry and Biochemistry, The Czech Academy of Sciences, Czech Republic
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Sursyakova VV, Levdansky VA, Rubaylo AI. Electrophoretic mobility of ester betulin derivatives and their complexation with γ-cyclodextrin studied by capillary electrophoresis in aqueous solutions at different pH values. Electrophoresis 2021; 43:535-542. [PMID: 34761422 DOI: 10.1002/elps.202100173] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 11/06/2021] [Accepted: 11/06/2021] [Indexed: 11/05/2022]
Abstract
In this article, capillary electrophoresis was used to measure the effective electrophoretic mobility of ester betulin derivatives as a pH function and to study their complexation with γ-cyclodextrin (γ-CD). The electrophoretic mobility of betulin 3,28-diphthalate (DPhB) and 3,28-disuccinate (DScB) changed unusually with decreasing pH: instead of decreasing, it first increased and then decreased. This fact as well as the turbidity of sample solutions at pH from 2.5 to 6, broadening of electrophoretic peaks and a decrease in the surface tension of the solutions indicates that these betulin derivatives, being amphiphilic compounds and weak acids, exist as micelles in aqueous solutions at pH 6 and below. The inclusion complexation of betulin derivatives with γ-CD at pH 9.18 and 4.5 was studied by mobility shift affinity capillary electrophoresis. At pH 9.18, the apparent binding (stability) constant logarithms for 1:1 γ-CD complexes of DPhB, betulin 3,28-disulfate (DSB) and DScB with 95% confidence interval limits were equal to 7.44 ± 0.02, 7.09 (7.01-7.19), and 6.97 (6.87-7.08) at 25°C, respectively. At pH 4.5, the binding constant for the DSB complex was slightly lower, while the micelle formation did not allow determining the exact values of the constants for the DPhB and DScB complexes.
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Affiliation(s)
- Viktoria V Sursyakova
- Institute of Chemistry and Chemical Technology SB RAS, Federal Research Center "Krasnoyarsk Science Center SB RAS", Krasnoyarsk, Russia
| | - Vladimir A Levdansky
- Institute of Chemistry and Chemical Technology SB RAS, Federal Research Center "Krasnoyarsk Science Center SB RAS", Krasnoyarsk, Russia
| | - Anatoly I Rubaylo
- Institute of Chemistry and Chemical Technology SB RAS, Federal Research Center "Krasnoyarsk Science Center SB RAS", Krasnoyarsk, Russia.,Siberian Federal University, Krasnoyarsk, Russia
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Čepa A, Dejmková V, Lešetický L, Jelínek I, Smrček S, Štícha M, Jašprová J, Urbanová M, Goncharova I, Dračínský M, Procházková E, Ostrow DJ, Vítek L. Physico-chemical characterization of bilirubin-10-sulfonate and comparison of its acid-base behavior with unconjugated bilirubin. Sci Rep 2021; 11:12896. [PMID: 34145377 PMCID: PMC8213708 DOI: 10.1038/s41598-021-92377-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 06/09/2021] [Indexed: 11/10/2022] Open
Abstract
Unconjugated bilirubin (UCB) is the end-product of heme catabolism in the intravascular compartment. Although beneficial for human health when mildly elevated in the body, when present at greater than a critical threshold concentration, UCB exerts toxic effects that are related to its physico-chemical properties, particularly affecting the central nervous system. The aim of the present study was to characterize bilirubin-10-sulfonate (ranarubin), a naturally occurring bile pigment, including determination of its mixed acidity constants (pKa*). Thanks to the presence of the sulfonic acid moiety, this compound is more polar compared to UCB, which might theoretically solve the problem with an accurate determination of the UCB pKa* values of its propionic acid carboxylic groups. Bilirubin-10-sulfonate was synthesized by modification of a previously described procedure; and its properties were studied by mass spectrometry (MS), nuclear magnetic resonance (NMR), infrared (IR), and circular dichroism (CD) spectroscopy. Determination of pKa* values of bilirubin-10-sulfonate and UCB was performed by capillary electrophoresis with low pigment concentrations in polar buffers. The identity of the synthesized bilirubin-10-sulfonate was confirmed by MS, and the pigment was further characterized by NMR, IR, and CD spectroscopy. The pKa values of carboxylic acid moieties of bilirubin-10-sulfonate were determined to be 5.02, whereas those of UCB were determined to be 9.01. The physico-chemical properties of bilirubin-10-sulfonate were partially characterized with low pKa* values compared to those of UCB, indicating that bilirubin-10-sulfonate cannot be used as a surrogate pigment for UCB chemical studies. In addition, using a different methodological approach, the pKa* values of UCB were found to be in a mildly alkaline region, confirming the conclusions of a recent critical re-evaluation of this specific issue.
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Affiliation(s)
- Adam Čepa
- Department of Organic Chemistry, Faculty of Science, Charles University, Prague, Czech Republic
| | - Veronika Dejmková
- Department of Organic Chemistry, Faculty of Science, Charles University, Prague, Czech Republic
| | - Ladislav Lešetický
- Department of Organic Chemistry, Faculty of Science, Charles University, Prague, Czech Republic
| | - Ivan Jelínek
- Department of Organic Chemistry, Faculty of Science, Charles University, Prague, Czech Republic
| | - Stanislav Smrček
- Department of Organic Chemistry, Faculty of Science, Charles University, Prague, Czech Republic
| | - Martin Štícha
- Department of Organic Chemistry, Faculty of Science, Charles University, Prague, Czech Republic
| | - Jana Jašprová
- Institute of Medical Biochemistry and Laboratory Diagnostics, 1st Faculty of Medicine, Charles University, Na Bojišti 3, Praha 2, 12000, Czech Republic
| | - Marie Urbanová
- University of Chemistry and Technology, Prague, Czech Republic
| | | | - Martin Dračínský
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Eliška Procházková
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Donald J Ostrow
- GI/Hepatology Division, University of Washington School of Medicine, Seattle, WA, USA
| | - Libor Vítek
- Institute of Medical Biochemistry and Laboratory Diagnostics, 1st Faculty of Medicine, Charles University, Na Bojišti 3, Praha 2, 12000, Czech Republic. .,4th Department of Internal Medicine, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
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Selimoğlu F, Ünal N, Ceren Ertekin Z, Dinç E. PARAFAC and MCR-ALS approaches to the pKa determination of benzoic acid and its derivatives. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 248:119253. [PMID: 33302215 DOI: 10.1016/j.saa.2020.119253] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Revised: 11/24/2020] [Accepted: 11/26/2020] [Indexed: 06/12/2023]
Abstract
In general, the identification of biological activities of a molecule requires the observation of its physicochemical characteristics with its molecular interactions in an organism. The acid-base ionization constant (or pKa) is one of the key parameters that shows the physicochemical behaviors of molecules used in pharmaceuticals, foods, cosmetics etc. Therefore, the development of new methods (or approaches) is necessary to get simple, rapid, inexpensive and reliable determination of the acidity constants of active and inactive ingredients used in commercial products. In this paper, new UV spectroscopic methods were developed for the first time, by applying parallel factor analysis (PARAFAC) and multivariate curve resolution-alternating least squares (MCR-ALS) to the pH-UV spectral data arrays for determining the pKa values of benzoic acid and its five derivatives (4-fluorobenzoic acid, thiosalicylic acid, anthranilic acid, phthalic acid, 4-aminobenzoic acid). The pH profiles obtained by the PARAFAC and MCR-ALS decomposition of the pH-UV data arrays were used for the quantitative estimation of the acid-base ionization constants for the investigated compounds without classical titration procedure. We concluded that the proposed PARAFAC and MCR-ALS provided us an opportunity for simple and rapid pKa determination of relevant compounds, which have functional importance in pharmaceutical and food industries.
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Affiliation(s)
- Faysal Selimoğlu
- Necmettin Erbakan University, Faculty of Science, Department of Biotechnology, 42090 Meram, Konya, Turkey
| | - Nazangül Ünal
- Ankara University, Faculty of Pharmacy, Department of Analytical Chemistry, 06560 Yenimahalle, Ankara, Turkey
| | - Zehra Ceren Ertekin
- Ankara University, Faculty of Pharmacy, Department of Analytical Chemistry, 06560 Yenimahalle, Ankara, Turkey
| | - Erdal Dinç
- Ankara University, Faculty of Pharmacy, Department of Analytical Chemistry, 06560 Yenimahalle, Ankara, Turkey.
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Šolínová V, Brynda J, Šícha V, Holub J, Grűner B, Kašička V. Determination of acidity constants, ionic mobilities, and hydrodynamic radii of carborane-based inhibitors of carbonic anhydrases by capillary electrophoresis. Electrophoresis 2021; 42:910-919. [PMID: 33405254 DOI: 10.1002/elps.202000298] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 12/08/2020] [Accepted: 12/31/2020] [Indexed: 12/17/2022]
Abstract
Capillary electrophoresis (CE) has been applied for determination of the thermodynamic acidity constants (pKa ) of the sulfamidoalkyl and sulfonamidoalkyl groups, the actual and limiting ionic mobilities and hydrodynamic radii of important compounds, eight carborane-based inhibitors of carbonic anhydrases, which are potential new anticancer drugs. Two types of carboranes were investigated, (i) icosahedral cobalt bis(dicarbollide)(1-) ion with sulfamidoalkyl moieties, and (ii) 7,8-nido-dicarbaundecaborate with sulfonamidoalkyl side chains. First, the mixed acidity constants, pKa mix , of the sulfamidoalkyl and sulfonamidoalkyl groups of the above carboranes and their actual ionic mobilities were determined by nonlinear regression analysis of the pH dependences of their effective electrophoretic mobility measured by capillary electrophoresis in the pH range 8.00-12.25, at constant ionic strength (25 mM), and constant temperature (25°C). Second, the pKa mix were recalculated to the thermodynamic pKa s using the Debye-Hückel theory. The sulfamidoalkyl and sulfonamidoalkyl groups were found to be very weakly acidic with the pKa s in the range 10.78-11.45 depending on the type of carborane cluster and on the position and length of the alkyl chain on the carborane scaffold. These pKa s were in a good agreement with the pKa s (10.67-11.27) obtained by new program AnglerFish (freeware at https://echmet.natur.cuni.cz), which provides thermodynamic pKa s and limiting ionic mobilities directly from the raw CE data. The absolute values of the limiting ionic mobilities of univalent and divalent carborane anions were in the range 18.3-27.8 TU (Tiselius unit, 1 × 10-9 m2 /Vs), and 36.4-45.9 TU, respectively. The Stokes hydrodynamic radii of univalent and divalent carborane anions varied in the range 0.34-0.52 and 0.42-0.52 nm, respectively.
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Affiliation(s)
- Veronika Šolínová
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague 6, Czechia
| | - Jiří Brynda
- Institute of Molecular Genetics of the Czech Academy of Sciences, Prague 4, Czechia
| | - Václav Šícha
- Institute of Inorganic Chemistry of the Czech Academy of Sciences, Husinec-Řež, Czechia
| | - Josef Holub
- Institute of Inorganic Chemistry of the Czech Academy of Sciences, Husinec-Řež, Czechia
| | - Bohumír Grűner
- Institute of Inorganic Chemistry of the Czech Academy of Sciences, Husinec-Řež, Czechia
| | - Václav Kašička
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague 6, Czechia
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