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  • 1
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    Online Resource
    Statistical evaluation of CZE‐UV and CZE‐ESI‐MS data of intact α‐1‐acid glycoprotein isoforms for their use as potential biomarkers in bladder cancer
    Wiley ; 2011
    In:  PROTEOMICS – Clinical Applications Vol. 5, No. 3-4 ( 2011-04), p. 205-205
    Details
    In: PROTEOMICS – Clinical Applications, Wiley, Vol. 5, No. 3-4 ( 2011-04), p. 205-205
    Abstract: This article was originally published in Electrophoresis 2010, 31 , 3314–3325, DOI 10.1002/elps.200900244
    Type of Medium: Online Resource
    ISSN: 1862-8346 , 1862-8354
    URL: Issue
    URL: Article
    DOI: 10.1002/prca.v5.3/4
    DOI: 10.1002/prca.201190022
    Language: English
    Publisher: Wiley
    Publication Date: 2011
    detail.hit.zdb_id: 2317130-3
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  • 2
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    Isomerization and epimerization of the aspartyl tetrapeptide A la‐ P he‐ A sp‐ G ly OH at p H 10—A CE study
    Wiley ; 2013
    In:  ELECTROPHORESIS Vol. 34, No. 18 ( 2013-09), p. 2666-2673
    Details
    In: ELECTROPHORESIS, Wiley, Vol. 34, No. 18 ( 2013-09), p. 2666-2673
    Abstract: Isomerization and enantiomerization of A sp in the tetrapeptide A la‐ P he‐ A sp‐ G ly OH are studied at p H 10 and 80°C as well as 25°C. CE ‐ MS allowed the distinction between α‐ A sp and β‐ A sp linkages in degradation products based on the ratio of the b and y fragment ions. Besides isomerization and enantiomerization of A sp, enantiomerization of A la and P he was also observed at both temperatures by chiral amino acid HPLC analysis using M arfey's reagent for derivatization. The rate of enantiomerization of the amino acids proceeded in the order A sp 〉 A la 〉 P he. The CE assay was validated with respect to linearity, LOQ , LOD , and precision and employed to characterize the time course of the degradation of the tetrapeptide upon incubation in borate buffer, p H 10. Isomerization to β‐ A sp peptides was identified as the major degradation reaction. The configuration of A sp or A la affected the half‐life of the starting peptide to a minor extent but did not influence the distribution of the individual products under equilibrium conditions at 80°C. Degradation at 25°C proceeded very slowly so that the equilibrium was not reached after 245 days.
    Type of Medium: Online Resource
    ISSN: 0173-0835 , 1522-2683
    URL: Issue
    URL: Article
    DOI: 10.1002/elps.v34.18
    DOI: 10.1002/elps.201200685
    Language: English
    Publisher: Wiley
    Publication Date: 2013
    detail.hit.zdb_id: 1475486-1
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  • 3
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    Alignment of laser‐induced fluorescence and mass spectrometric detection traces using electrophoretic mobility scaling in CE‐LIF‐MS of labeled N ‐glycans
    Wiley ; 2012
    In:  ELECTROPHORESIS Vol. 33, No. 4 ( 2012-02), p. 563-566
    Details
    In: ELECTROPHORESIS, Wiley, Vol. 33, No. 4 ( 2012-02), p. 563-566
    Abstract: The combination of optical detection techniques like photometry (UV) or laser‐induced fluorescence (LIF) with mass spectrometry for capillary electrophoresis offers advantages, both for later use of stand‐alone CE‐UV or CE‐LIF systems and for combined CE‐UV‐MS or CE‐LIF‐MS analysis. Faster method development is enabled, the identification of analytes is facilitated, and it allows christian the optical detection scheme to be used for more precise quantification. However, shortcomings of current methodology and equipment hindered the broader use of such detection combinations mainly due to the long distance between the detection points (at least 20 cm). Large shifts in migration times and changes in resolution are visible between the detection traces hindering their straightforward comparison. We present here novel equipment for a robust coupling of CE‐LIF‐MS with the shortest possible distance between detection points (12 cm) determined by the length of the electrospray needle. In addition, we encourage the use of a normalization of detection traces using a scale of effective electrophoretic mobility to obtain the same x ‐scale for both detection traces. As an example, the proposed methodology is applied to a mixture of labeled as well as non‐labeled N ‐glycans.
    Type of Medium: Online Resource
    ISSN: 0173-0835 , 1522-2683
    URL: Issue
    URL: Article
    DOI: 10.1002/elps.v33.4
    DOI: 10.1002/elps.201100367
    Language: English
    Publisher: Wiley
    Publication Date: 2012
    detail.hit.zdb_id: 1475486-1
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  • 4
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    In‐line SPE ‐ CE using a fritless bead string design— A pplication for the analysis of organic sulfonates including inline SPE ‐ CE ‐ MS for APTS ‐labeled glycans
    Wiley ; 2014
    In:  ELECTROPHORESIS Vol. 35, No. 9 ( 2014-05), p. 1236-1243
    Details
    In: ELECTROPHORESIS, Wiley, Vol. 35, No. 9 ( 2014-05), p. 1236-1243
    Abstract: Despite many advantages like high separation efficiency CE comprises the main limitation of low concentration sensitivity, when compared to HPLC . In‐line SPE is an efficient way to increase concentration sensitivity. Here, a fritless in‐line‐ SPE ‐ CE ‐ MS method was developed in order to analyze anions of strong acids. Mixed‐mode (weak anion exchange and RP ) particles were used for enrichment and an acidic BGE was applied for separation. Different particle and capillary sizes were tested. A novel bead string design with a 100 μm id column filled with particles of 90 μm followed by a separation capillary with 50 μm id was easy to prepare and showed the best performance with respect to separation efficiency and reproducibility. Three aromatic sulfonic acids were employed in an in‐line SPE ‐ CE ‐ UV approach for method development. Method validation was performed with respect to reproducibility, robustness, and linearity. Thereafter the method was transferred to SPE ‐ CE ‐ MS and applied to the analysis of glycans labeled with 8‐aminopyrene‐1,3,6‐trisulfonic acid. Lower limits of detection in the low nM range were achieved injecting about 10 μL of sample. This corresponds to an enrichment factor of more than 800 compared to the corresponding CE ‐ MS method without preconcentration.
    Type of Medium: Online Resource
    ISSN: 0173-0835 , 1522-2683
    URL: Issue
    URL: Article
    DOI: 10.1002/elps.v35.9
    DOI: 10.1002/elps.201300388
    Language: English
    Publisher: Wiley
    Publication Date: 2014
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  • 5
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    Toward a screening method for the analysis of small intact proteins by CE‐ESI‐TOF MS
    Wiley ; 2012
    In:  ELECTROPHORESIS Vol. 33, No. 9-10 ( 2012-05), p. 1356-1366
    Details
    In: ELECTROPHORESIS, Wiley, Vol. 33, No. 9-10 ( 2012-05), p. 1356-1366
    Abstract: Capillary electrophoresis‐mass spectrometry (CE‐MS) more and more gains in importance as an analytical technique for the identification and characterization of intact proteins in the biopharmaceutical area. Thus, a CE‐ESI‐MS method was optimized and validated systematically with respect to the improved screening and characterization of intact proteins. The optimization was accomplished by variation of different CE‐MS parameters, such as capillary coating, background electrolyte, sheath liquid, and nebulizer gas pressure, while monitoring both the resolution and signal intensities. Achievable separation is discussed quantitatively in the context of the coating and the resulting EOF , the protein mobilities, and the suction effect of the sprayer. The observed precisions of the optimized method regarding the migration times (mean RSD = 1.4%) and peak areas (mean RSD = 12.3%) and an extensive principal component analysis revealed that the presented method is reliable and useful for the quantitation of intact proteins and protein isoforms. The applicability of this method to various proteins showing different characteristics (p I value, molecular mass, hydrophobicity, etc.) is discussed. The presented method will contribute to the improved characterization of a large variety of intact proteins in the biomedical and pharmaceutical area.
    Type of Medium: Online Resource
    ISSN: 0173-0835 , 1522-2683
    URL: Issue
    URL: Article
    DOI: 10.1002/elps.v33.9-10
    DOI: 10.1002/elps.201100620
    Language: English
    Publisher: Wiley
    Publication Date: 2012
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  • 6
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    Capillary electrophoresis/mass spectrometry relevant to pharmaceutical and biotechnological applications
    Wiley ; 2012
    In:  ELECTROPHORESIS Vol. 33, No. 11 ( 2012-06), p. 1517-1530
    Details
    In: ELECTROPHORESIS, Wiley, Vol. 33, No. 11 ( 2012-06), p. 1517-1530
    Abstract: Advanced analytical techniques play a crucial role in the pharmaceutical and biotechnological field. In this context, capillary electrophoresis/mass spectrometry ( CE / MS ) has attracted attention due to efficient and selective separation in combination with powerful detection allowing identification and detailed characterization. Method developments and applications of CE / MS have been focused on questions not easily accessible by liquid chromatography/mass spectrometry ( LC / MS ) as the analysis of intact proteins, carbohydrates, and various small molecules, including peptides. Here, recent approaches and applications of CE / MS relevant to (bio)pharmaceuticals are reviewed and discussed to show actual developments and future prospects. Based on other reviews on related subjects covering large parts of previous works, the paper is focused on general ideas and contributions of the last 2 years; for the analysis of glycans, the period is extended back to 2006.
    Type of Medium: Online Resource
    ISSN: 0173-0835 , 1522-2683
    URL: Issue
    URL: Article
    DOI: 10.1002/elps.v33.11
    DOI: 10.1002/elps.201200030
    Language: English
    Publisher: Wiley
    Publication Date: 2012
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  • 7
    Online Resource
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    Statistical evaluation of CZE‐UV and CZE‐ESI‐MS data of intact α‐1‐acid glycoprotein isoforms for their use as potential biomarkers in bladder cancer
    Wiley ; 2010
    In:  ELECTROPHORESIS Vol. 31, No. 19 ( 2010-10), p. 3314-3325
    Details
    In: ELECTROPHORESIS, Wiley, Vol. 31, No. 19 ( 2010-10), p. 3314-3325
    Abstract: α‐1‐acid glycoprotein (AGP) is a highly heterogeneous protein that presents a vast number of isoforms (molecules of the protein differing in its peptidic and/or glycosidic moieties). In the last years, several authors have studied the potential use of AGP as a cancer biomarker. These studies focus on the correlation of different features of AGP structure ( i.e. fucosylation, antennarity) with cancer or on the total protein blood concentration. In this study, the potential of CZE‐UV and CZE‐ESI‐MS analysis of intact AGP isoforms to study the correlation of this protein with bladder cancer is shown. Samples from 16 individuals (eight healthy, eight bladder cancer) were analyzed and characterized in great detail including data on intact protein isoforms and on released glycans. The analytical data were evaluated employing different statistical techniques (ANOVA; principal component analysis, PCA; linear discriminant analysis; and partial least squares‐discriminant analysis). Statistical differences between the two groups of study were observed. The best results were obtained by linear discriminant analysis of the CZE‐ESI‐MS data for intact AGP isoforms (93.75% of correct classification). Due to MS characterization, it can be observed that differences between the samples are mainly due to higher abundance of AGP isoforms containing tri‐ and tetra‐antennary fucosylated oligosaccharides in cancer patients. The results show the great potential of CE‐MS in combination with advanced data processing for the use of intact protein isoforms as disease biomarkers.
    Type of Medium: Online Resource
    ISSN: 0173-0835 , 1522-2683
    URL: Issue
    URL: Article
    DOI: 10.1002/elps.v31:19
    DOI: 10.1002/elps.201000244
    Language: English
    Publisher: Wiley
    Publication Date: 2010
    detail.hit.zdb_id: 1475486-1
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  • 8
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    The selective determination of sulfates, sulfonates and phosphates in urine by CE‐MS
    Wiley ; 2010
    In:  ELECTROPHORESIS Vol. 31, No. 7 ( 2010-04), p. 1274-1281
    Details
    In: ELECTROPHORESIS, Wiley, Vol. 31, No. 7 ( 2010-04), p. 1274-1281
    Abstract: Metabolite identification and metabolite profiling are of major importance in the pharmaceutical and clinical context. However, highly polar and ionic substances are rarely included as analytical tools are missing. In this study, we present a new method for the determination of urinary sulfates, sulfonates, phosphates and other anions of strong acids. The method comprises a CE separation using an acidic BGE (pH≤2) and anodic detection by MS via negative ESI. In this way, only sulfates and sulfonates are detected in the first part of the electropherogram, followed by phosphates and potentially highly acidic carboxylates. The selectivity for sulfur‐containing species is proved using extracted ion electropherograms based on certain isotopic ratios. Ethyl sulfate can be determined by this method and, thus, CE‐MS can be used for determination of this alcohol consumption marker. An SPE method was developed for the extraction of ethyl sulfate and other organic anions. Several additional compounds can be identified based on the accurate mass determined by the TOF MS in conjunction with databases. However, numerous detected compounds have not been reported in urinary metabolite databases so far. Thus, it is demonstrated that the presented method is complementary to the existing methods for metabolite characterization in urine.
    Type of Medium: Online Resource
    ISSN: 0173-0835 , 1522-2683
    URL: Issue
    URL: Article
    DOI: 10.1002/elps.v31:7
    DOI: 10.1002/elps.200900719
    Language: English
    Publisher: Wiley
    Publication Date: 2010
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  • 9
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    CE‐MS characterization of negatively charged α‐, β‐ and γ‐CD derivatives and their application to the separation of dipeptide and tripeptide enantiomers by CE
    Wiley ; 2010
    In:  ELECTROPHORESIS Vol. 31, No. 9 ( 2010-05), p. 1498-1505
    Details
    In: ELECTROPHORESIS, Wiley, Vol. 31, No. 9 ( 2010-05), p. 1498-1505
    Abstract: Sulfated, sulfopropyl and carboxymethyl α‐, β‐ and γ‐CDs were characterized by CE‐ESI‐MS using an acidic BGE with anodic MS detection and a basic BGE with cathodic MS detection. Isomers of the sulfated CDs comigrated in both systems. The acidic BGE with anodic MS detection resulted in slightly better separation of the isomers of the sulfopropyl CDs, which were separated according to the number of substituents. In the case of carboxymethyl CDs, isomers with an identical number of substituents but with a different substitution pattern with regard to substitution of the primary and secondary hydroxyl groups of the CDs could be separated using the basic BGE. The separation of the LL and DD enantiomers of dipeptides and tripeptides using the CDs was studied with regard to the amino acid sequence and the nature of the CDs. Standardized conditions with regard to buffer pH, CD concentration and voltage were applied. The peptides were analyzed at pH 2.5 as positively charged compounds and at pH 5.3 as neutral zwitterions. The β‐CD derivatives were more effective chiral selectors for the investigated peptides followed by the α‐CD derivatives. The γ‐CDs were the least effective selectors. The enantiomer migration order depended on both the CD and the amino acid sequence of the peptides. For several combinations, pH‐dependent reversal of the enantiomer migration order was also observed.
    Type of Medium: Online Resource
    ISSN: 0173-0835 , 1522-2683
    URL: Issue
    URL: Article
    DOI: 10.1002/elps.v31:9
    DOI: 10.1002/elps.200900677
    Language: English
    Publisher: Wiley
    Publication Date: 2010
    detail.hit.zdb_id: 1475486-1
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  • 10
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    Evaluation of the effect of the immunopurification‐based procedures on the CZE‐UV and CZE‐ESI‐TOF‐MS determination of isoforms of intact α‐1‐acid glycoprotein from human serum
    Wiley ; 2010
    In:  ELECTROPHORESIS Vol. 31, No. 11 ( 2010-06), p. 1796-1804
    Details
    In: ELECTROPHORESIS, Wiley, Vol. 31, No. 11 ( 2010-06), p. 1796-1804
    Abstract: Differences in α‐1‐acid glycoprotein (AGP) peptidic and glycan moieties originate several isoforms, whose modifications have been related to different pathophysiological situations. Differences in the isoforms of AGP existing in serum of individuals suffering from different diseases compared to healthy ones could be potentially used as biomarkers. CZE has been proven to be a useful technique for the analysis of glycoprotein isoforms. However, direct CZE analysis of AGP isoforms in serum samples needs efficient purification methods that allow the protein analysis. In this work two new and fast methods to purify AGP from human serum are evaluated in regard to their effect on the determination of isoforms of the intact glycoprotein by CZE‐UV and by a developed CZE‐ESI‐TOF‐MS method. Both preparation methods, which differ in the pre‐treatment of the sample prior to an anti‐AGP immunochromatographic step are shown to be adequate to analyze isoforms of intact AGP. Comparison of both purification methods by CZE‐UV and CZE‐ESI‐TOF‐MS indicates that serum AGP purified without acidic precipitation as pre‐treatment is more adequate due to AGP higher yield, which leads to better CZE‐Mass spectra. Both CZE methods show no indication that acidic precipitation influences the glycosylation (including sialylation) of AGP.
    Type of Medium: Online Resource
    ISSN: 0173-0835 , 1522-2683
    URL: Issue
    URL: Article
    DOI: 10.1002/elps.v31:11
    DOI: 10.1002/elps.200900680
    Language: English
    Publisher: Wiley
    Publication Date: 2010
    detail.hit.zdb_id: 1475486-1
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