Determination of pKa values of diastereomers of phosphinic pseudopeptides by CZE

Koval, Dušan; Kašička, Václav; Jiráček, Jiřı́; Collinsová, Michaela

doi:10.1002/elps.200600133

Cited by 28 publications

(38 citation statements)

References 20 publications

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“…(5) and (8) for dissociation of protonated nitrogen of pyridine moiety in aza [6]helicenes, and Eqs. (5), (15), and (16) for the dissociation of protonated nitrogens of pyridine moieties in 1,14-diaza [5]helicene. The values of thermodynamic pK a are given in Table 2; they were in the range of 4.94 -8.85.…”

Section: Determination Of Thermodynamic Dissociation Constantsmentioning

confidence: 99%

Determination of acid–base dissociation constants of azahelicenes by capillary zone electrophoresis

Ehala

Míšek

Stará̈

et al. 2008

J of Separation Science

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CZE was employed to determine acid-base dissociation constants (pK(a)) of ionogenic groups of azahelicenes in methanol (MeOH). Azahelicenes are unique 3-D aromatic systems, which consist of ortho-fused benzene/pyridine units and exhibit helical chirality. The pK(a) values of pyridinium groups of the studied azahelicenes were determined from the dependence of their effective electrophoretic mobility on pH by a nonlinear regression analysis. The effective mobilities of azahelicenes were determined by CZE at pH range between 2.1 and 10.5. Thermodynamic pK(a) values of monobasic 1-aza[6]helicene and 2-aza[6]helicene in MeOH were determined to be 4.94 +/- 0.05 and 5.68 +/- 0.05, respectively, and pK(a) values of dibasic 1,14-diaza[5]helicene were found to be equal to 7.56 +/- 0.38 and 8.85 +/- 0.26. From these values, the aqueous pK(a) of these compounds was estimated.

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Section: Determination Of Thermodynamic Dissociation Constantsmentioning

confidence: 99%

Determination of acid–base dissociation constants of azahelicenes by capillary zone electrophoresis

Ehala

Míšek

Stará̈

et al. 2008

J of Separation Science

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“…9. Separation of the diastereomers of phosphinic pseudopeptides, i.e., peptides with one peptide bond substituted by phosphinic acid moiety, -P(O)OH-CH 2 -, derived from the 2 , has been investigated in achiral BGEs within a broad pH range, 1.8-12.0 [230]. The best resolution was achieved in the acid pH region around the pK a values of the central phosphinic acid group of the pseudopeptides but successful separation of some diastereomers was achieved also in neutral and alkaline BGEs.…”

Section: Chiral Analysis and Stereoisomer Separationmentioning

confidence: 99%

“…Effective and ionic mobilities of phosphinic pseudopeptides, peptide isosteres with one peptide bond substituted by a phosphinic acid moiety -P(O)OH-CH 2 -, and pK a of this moiety and other ionogenic groups (C-terminal-, g-Glu-and b-Asp-carboxyl, N-terminal-and e-Lys amino, His-imidazolyl) have been determined from the precise measurements of the pH dependence of effective mobilities within a broad pH range 1.8-12.0 in BGEs with constant ionic strength (25 mM) [230]. Effective mobilities, corrected to standard temperature 257C, were subjected to nonlinear regression analysis and the obtained apparent pK a values were recalculated to thermodynamic pK a values by extrapolation to zero ionic strength according to extended Debye-Hückel model.…”

Section: Physicochemical Characterizationmentioning

confidence: 99%

Recent developments in CE and CEC of peptides

Kašička

2007

Electrophoresis

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118

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The article brings a comprehensive survey of recent developments and applications of high-performance capillary electromigration methods, zone electrophoresis, ITP, IEF, affinity electrophoresis, EKC, and electrochromatography, to analysis, preparation, and physicochemical characterization of peptides. New approaches to the theoretical description and experimental verification of electromigration behavior of peptides and to methodology of their separations, such as sample preparation, adsorption suppression, and detection, are presented. Novel developments in individual CE and CEC modes are shown and several types of their applications to peptide analysis are presented: conventional qualitative and quantitative analysis, purity control, determination in biomatrices, monitoring of chemical and enzymatical reactions and physical changes, amino acid and sequence analysis, and peptide mapping of proteins. Some examples of micropreparative peptide separations are given and capabilities of CE and CEC techniques to provide important physicochemical characteristics of peptides are demonstrated.

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“…When neutral surfactants are employed, peptides can also be separated at low pH when they are positively charged and migrate toward the cathode. (141,161) Compared to the system using SDS and high-pH buffers, this results in a reversal of the diastereomer migration order. (150) It is interesting to note that a reversal of the migration order was also observed for the peptide drug lisinopril by switching the surfactant from sodium cholate to SDS.…”

Section: Micellar Electrokinetic Chromatographymentioning

confidence: 99%

Separation of Peptide Diastereomers

Scriba

2014

Encyclopedia of Analytical Chemistry

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Diastereomeric peptides, isomers in which one or more of the chiral centers have been converted to the opposite configuration (R or S, D or L ), often possess different biological activities and/or conformational properties. Therefore, the separation and determination of diastereomeric peptides is important in life sciences and particularly significant to the pharmaceutical industry for quality control of peptide synthesis and stability as well as for regulatory requirements. Diastereomers differ in their physicochemical properties that can be utilized for their determination by numerous techniques. In contrast to many other methods such as optical rotation, circular dichroism, differential scanning calorimetry, or infrared (IR) spectroscopy, separation techniques such as chromatography or capillary electrophoresis (CE) allow the sensitive and simultaneous identification and quantification of peptide diastereomers. This chapter covers analytical‐scale separation of peptide diastereomers by chromatographic methods, including paper chromatography (PC), thin‐layer chromatography (TLC), gas chromatography (GC), high‐performance liquid chromatography (HPLC), and CE. HPLC is currently the predominantly used method for peptide diastereomer separations. However, owing to the high resolving power, particularly for polar compounds, CE has been applied to the separation of diastereomeric peptides in recent years. The chapter focuses on methods employing achiral stationary phases or buffers without chiral additives for the separations, although some examples of such separations, i.e. the use of chiral columns or chiral mobile phase additives, are mentioned. Moreover, only diasteromeric peptides containing natural amino acids will be discussed.

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Determination of pK_a values of diastereomers of phosphinic pseudopeptides by CZE

Cited by 28 publications

References 20 publications

Determination of acid–base dissociation constants of azahelicenes by capillary zone electrophoresis

Determination of acid–base dissociation constants of azahelicenes by capillary zone electrophoresis

Recent developments in CE and CEC of peptides

Separation of Peptide Diastereomers

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