The behaviour of native orosomucoid in acid and alkaline media

Karpenko, V.; Kalous, V.

doi:10.1135/cccc19770045

Cited by 11 publications

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“…AGP contains numerous ionizable sidechains with strongly different pK a values (e.g., arginine through glutamic and sialic acids) sensitizing the AGP surface against the changes of the eluent pH. 11,12 As a consequence, the changes in the protonation state of the selector may influence the conformation and therefore the binding properties of the stationary phase.…”

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Study on the sorption properties of α₁‐acid glycoprotein (AGP)‐based stationary phase modified by organic solvents

et al. 2003

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An alpha(1)-acid glycoprotein, immobilized on silica (Chiral-AGP) is one of the most widely used chiral stationary phases for the enantiomeric separation of a wide variety of chiral drugs with several applications in the biological and clinical field. The aim of this work was to study the sorption properties of the AGP-based stationary phase, which may have crucial importance for enantioselectivity. New binding data to the mechanism of the chromatographic separation are presented. The sorption of both organic solvents, i.e., acetonitrile and dioxane, shows remarkable pH dependency. A fluorescence quenching study was carried out to elucidate structural changes of AGP in the presence of acetonitrile using 2,2,2-trichloroethanol as fluorescence quencher.

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confidence: 99%

Study on the sorption properties of α₁‐acid glycoprotein (AGP)‐based stationary phase modified by organic solvents

et al. 2003

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“…The pK a values of these basic groups are in the range of 6.6-9.7. 38 Since the pK a value of the acidic amino acid, glutamic is close to the running pH, it is dissociated to 42%, while sialic acids and aspartic acids are dissociated to 96 and 92%. Summarizing the dissociated numbers of carboxylic acids and taking into account the numbers of positively charged amino acids gives an approximate net charge of -8, which was used in the calculation of the mobility of protein-solute complexes at different temperatures (Table 4).…”

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confidence: 99%

“…The mobility of the protein−solute complex cannot be easily obtained experimentally and was therefore obtained by applying the relationship between mobility and charge-to-size ratio: where 40 000 is the molecular weight of AGP and n is the net charge of the protein. The acidic groups in the protein consists of sialic acids, p K a = 2.6 (14/molecule 35 AGP), glutamic acids, p K a = 4.14, (21−20/molecule 34 ), aspartic acids, p K a = 2.95, (8−10/molecule 34 ). The basic amino acids in the protein are arginine (10−8/molecule 34 ), lysine, (9−10/molecule 34 ), and histidine (3/molecule 34 ).…”

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confidence: 99%

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Evaluation of Association Constants between Drug Enantiomers and Human α₁-Acid Glycoprotein by Applying a Partial-Filling Technique in Affinity Capillary Electrophoresis

Ahmad

Westerlund

1998

Anal. Chem.

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The principles for evaluation of conditional association constants between drug enantiomers and proteins, exemplified here by alpha 1-acid glycoprotein (AGP), using capillary zone electrophoresis employing a partial filling technique, is presented. In the partial filling technique only the first part of the capillary is filled with the selector, and this selector zone (plug) length can be varied by introducing the selector solution at different times at constant pressure. An important feature of the technique is the low consumption of selector solution in this study only 40-290 nL is used per run, of special importance when the availability of the selector is limited, and also in case it is expensive. Conditions are chosen so that the protein has a net negative charge and migrates toward the anode, while the analytes migrate toward the detector at the cathodic side. The resolution is linearly related to the effective plug length, as shown in separations of the enantiomers of disopyramide and remoxipride. The effective plug length can be calculated, which forms the basis to apply this technique for determinations of association constants. The association between the enantiomers of the solutes and AGP varied with increasing temperature, as shown by determined association constants. It was found that the association between the enantiomers and AGP was strongest at 25 degrees C and decreased at both lower and higher temperatures. This unexpected finding may indicate conformational changes of the protein with temperature variations.

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“…Approximate net charge (q) of the peptides was calculated by taking into account the charge of the N-terminal (pK a = Peptide charge was calculated by taking into account approximative values of pK a of Glu (pK a = 4.1), Asp (pK a = 3.0), Lys (pK a = 10), Arg (pK a = 12), His (pK a = 6.5), terminal amine (pK a = 8) and terminal carboxyl (pK a = 3.1) groups [50,51]. 8.0) and the C-terminal (pK a = 3.1) amino acids as well as the charge of acidic (Glu, pK a = 4.1 ; Asp, pK a = 3.0) and basic (Arg, pK a = 12 ; Lys, pK a = 10 ; His, pK a = 6.5) amino acid residues at pH 3.1 [49 -51] (Table 3).…”

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confidence: 99%

Analysis of calcitonin and its analogues by capillary zone electrophoresis and matrix‐assisted laser‐desorption ionization time‐of‐flight mass spectrometry

Ahmad¹,

Olofsson²

2004

J of Separation Science

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Capillary zone electrophoretic (CZE) separations and mass spectrometric analysis of salmon calcitonin and related analogues were performed to generate electrophoresis and mass fingerprints for quality control of the recombinant polypeptide pharmaceutical salmon calcitonin. The calcitonins and their corresponding tryptic digests were successfully separated by CZE at low pH in fused silica capillaries dynamically modified with poly-cationic polymers. The poly-cationic modified inner surface of the fused silica capillaries generated a strong anionic electroosmotic flow (EOF). Analytes of negative, neutral, and positive charge were all swept through the capillary toward the positive electrode. Compared to Polybrene-coated capillaries, capillaries coated with PEI showed a markedly slower but much more stable electroosmotic flow. The migration order of the analytes was predicted by comparing approximate values of the charge to (molecular mass)2/3 ratios. The predicted migration order was confirmed by off-line analysis of CZE fractions with matrix-assisted laser-desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS).

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The behaviour of native orosomucoid in acid and alkaline media

Cited by 11 publications

References 0 publications

Study on the sorption properties of α₁‐acid glycoprotein (AGP)‐based stationary phase modified by organic solvents

Study on the sorption properties of α₁‐acid glycoprotein (AGP)‐based stationary phase modified by organic solvents

Evaluation of Association Constants between Drug Enantiomers and Human α₁-Acid Glycoprotein by Applying a Partial-Filling Technique in Affinity Capillary Electrophoresis

Analysis of calcitonin and its analogues by capillary zone electrophoresis and matrix‐assisted laser‐desorption ionization time‐of‐flight mass spectrometry

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The behaviour of native orosomucoid in acid and alkaline media

Cited by 11 publications

References 0 publications

Study on the sorption properties of α1‐acid glycoprotein (AGP)‐based stationary phase modified by organic solvents

Study on the sorption properties of α1‐acid glycoprotein (AGP)‐based stationary phase modified by organic solvents

Evaluation of Association Constants between Drug Enantiomers and Human α1-Acid Glycoprotein by Applying a Partial-Filling Technique in Affinity Capillary Electrophoresis

Analysis of calcitonin and its analogues by capillary zone electrophoresis and matrix‐assisted laser‐desorption ionization time‐of‐flight mass spectrometry

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Product

Resources

About

Study on the sorption properties of α₁‐acid glycoprotein (AGP)‐based stationary phase modified by organic solvents

Study on the sorption properties of α₁‐acid glycoprotein (AGP)‐based stationary phase modified by organic solvents

Evaluation of Association Constants between Drug Enantiomers and Human α₁-Acid Glycoprotein by Applying a Partial-Filling Technique in Affinity Capillary Electrophoresis