Analysis and characterization of phosphinic pseudopeptides by capillary zone electrophoresis

Koval, Dušan; Kašička, Václav; Jiráček, Jiřı́; Collinsová, Michaela; Garrow, Timothy A.

doi:10.1002/1522-2683(200202)23:2<215::aid-elps215>3.0.co;2-p

Cited by 21 publications

(8 citation statements)

References 20 publications

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“…This is a lower value than 2.5%/7C value used in our previous paper [26] where the procedure for temperature correction of mobilities is described in more detail. We have preferred this lower value from a generally acceptable 2-2.5%/7C range of this coefficient since using 2.5%/7C value resulted in overestimated temperature corrections of the mobilities at relatively high input power used in the most acidic BGEs.…”

Section: Correction Of Mobilities To Standard Temperaturementioning

confidence: 62%

Physicochemical characterization of phosphinic pseudopeptides by capillary zone electrophoresis in highly acidic background electrolytes

et al. 2003

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Phosphinic pseudopeptides (i.e., peptide isosteres with one peptide bond replaced by a phosphinic acid moiety) were analyzed and physicochemically characterized by capillary zone electrophoresis in the pH range of 1.1-3.2, employing phosphoric, phosphinic, oxalic and dichloroacetic acids as background electrolyte (BGE) constituents. The acid dissociation constant (pK(a)) of phosphinate group in phosphinic pseudopeptides and ionic mobilities of these analytes were determined from the pH dependence of their effective electrophoretic mobilities corrected to standard temperature and constant ionic strength of the BGEs. It was shown that these corrections are necessary whenever precise mobility data at very low pH are to be determined. Additionally, it was found that the ionic mobilities of the phosphinic pseudopeptides and pK(a) of their phosphinate group are affected by the BGE constituent used. The variability of migration behavior of the pseudopeptides can be attributed to their ion-pairing formation with the BGE components.

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Section: Correction Of Mobilities To Standard Temperaturementioning

confidence: 62%

Physicochemical characterization of phosphinic pseudopeptides by capillary zone electrophoresis in highly acidic background electrolytes

et al. 2003

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“…Electrophoretic mobilities determined under these conditions may require the correction of temperature (Joule heating), viscosity, and ionic strength changes to a selected reference state prior to the estimation of stability constants . The measured effective electrophoretic mobility, μ, was therefore recalculated to the reference temperature T 0 of 25°C assuming the mobilities to have the same temperature dependence as found for the conductivity of the phosphate buffer BGE (α th = 0.022 per K):

μ_{0} = \frac{μ}{((), 1 + α_{t h} ((), T_{a i} - T_{0}))}

…”

Section: Methodsmentioning

confidence: 99%

Affinity capillary electrophoresis method for investigation of bile salts complexation with sulfobutyl ether‐β‐cyclodextrin

Østergaard

Jensen

Holm

2012

J of Separation Science

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Sulfobutyl ether-β-cyclodextrin (SBEβCD) is utilized in preformulation and drug formulation as an excipient for solubilization of drugs with poor aqueous solubility. Approximately seven negative charges of SBEβCD play a role with respect to solubilization and complexation, but also have an influence on the ionic strength of the background electrolyte when the cyclodextrin is used in capillary electrophoresis. Mobility-shift affinity capillary methods for investigation of the complexation of taurocholate and taurochenodeoxycholate with the negatively charged cyclodextrin derivative applying constant power and ionic strength conditions as well as constant voltage and varying ionic strength were investigated. A new approach for the correction of background electrolyte ionic strength was developed. Mobility-shift affinity capillary electrophoresis experiments obtained at constant voltage and constant power settings were compared and found to provide binding parameters that were in good agreement upon correction. The complexation of taurochenodeoxycholate with SBEβCD was significantly stronger than the corresponding interaction involving taurocholate. The obtained stability constants for the bile salts were in the same range as those previously reported for the interaction with neutral β-cyclodextrins derivatives, i.e. the positions of the negative charges on SBEβCD and the bile salts within the complex did not lead to significant electrostatic repulsion.

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“…Epoxypoly(dimethylacrylamide) (EPDMA) [12] was kindly donated by Dr. M. Chiari (CNR, Milan, Italy). Phosphinic pseudopeptides were synthesized as a mixture of four diastereomers and preparatively separated by HPLC as described elsewhere [2,13].…”

Section: Reagents and Chemicalsmentioning

confidence: 99%

Determination of pK_a values of diastereomers of phosphinic pseudopeptides by CZE

et al. 2006

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A CE method was used for the determination of acidity constants (pK(a)) of a series of ten phosphinic pseudopeptides, which varied in number and type of ionogenic groups. Effective electrophoretic mobilities were measured in the 1.8-12.0 pH range in the BGEs of constant ionic strength of 25 mM. Effective electrophoretic mobilities, corrected to standard temperature of 25 degrees C, were subjected to non-linear regression analysis and the obtained apparent pK(a) values were recalculated to thermodynamic pK(a)'s by extrapolation to zero ionic strength according to the extended Debye-Hückel model. The pK(a) values of the phosphinic acid group fell typically in the 1.5-2.25 interval, C-terminal carboxylic groups in the 2.94-3.50 interval, carboxylic groups of the lateral chain of glutamate and aspartate in the 4.68-4.97 interval, imidazolyl moiety of histidine in the 6.55-8.32 interval, N-terminal amino groups in the 7.65-8.28 interval and epsilon-amino group of the lateral chain of lysine in the 10.46-10.61 interval. Further, separation of diastereomers of the phosphinic pseudopeptides was investigated in achiral BGEs. Evaluation of the resolution of the diastereomers as a function of pH of the BGE revealed that most suitable pH region for separation of the diastereomers is around the pK(a) values of the central phosphinic acid group of the pseudopeptides. Successful separation of some diastereomers was, however, achieved in the neutral and alkaline BGEs as well.

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Analysis and characterization of phosphinic pseudopeptides by capillary zone electrophoresis

Cited by 21 publications

References 20 publications

Physicochemical characterization of phosphinic pseudopeptides by capillary zone electrophoresis in highly acidic background electrolytes

Physicochemical characterization of phosphinic pseudopeptides by capillary zone electrophoresis in highly acidic background electrolytes

Affinity capillary electrophoresis method for investigation of bile salts complexation with sulfobutyl ether‐β‐cyclodextrin

Determination of pK_a values of diastereomers of phosphinic pseudopeptides by CZE

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Analysis and characterization of phosphinic pseudopeptides by capillary zone electrophoresis

Cited by 21 publications

References 20 publications

Physicochemical characterization of phosphinic pseudopeptides by capillary zone electrophoresis in highly acidic background electrolytes

Physicochemical characterization of phosphinic pseudopeptides by capillary zone electrophoresis in highly acidic background electrolytes

Affinity capillary electrophoresis method for investigation of bile salts complexation with sulfobutyl ether‐β‐cyclodextrin

Determination of pKa values of diastereomers of phosphinic pseudopeptides by CZE

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Determination of pK_a values of diastereomers of phosphinic pseudopeptides by CZE