Protein glycosylation analysis with capillary-based electromigrative separation techniques

Statically Adsorbed Coatings for High Separation Efficiency and Resolution in CE-MS Peptide Analysis: Strategies and Implementation

Coatings are necessary to prevent protein and peptide adsorption to the capillary surface and obtain high intermediate precision. In this protocol, we first present our basic strategy to address peptide separation using three different coatings: one neutral and two cationic coatings, the latter largely differing in their induced electroosmotic mobility. In detail, we will describe how we apply the statically adsorbed coatings to obtain very high plate numbers and high repeatability.With some model examples, we clearly describe the scope of the method for the analysis of peptide samples: tryptic digests are addressed as well as small glycoproteins and glycopeptides largely differing in their effective electrophoretic mobility. We also show that the method is suitable for a fast screening of peptide samples despite a high matrix load comprising of up to 500 mmol/L sodium chloride. We demonstrate that this basic CE-MS method is rather independent of the polarity of the analytes with a very fast near-baseline separation of very hydrophobic Aβ peptides related to the onset of Alzheimer's disease. These examples will give an impression, which coating is most suitable for a specific analytical application.Special attention is paid to difficult aspects of the coating procedure and the CE-MS method, e.g., the potential of cross-contamination when changing the coatings.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: an update for 2009-2010

This review is the sixth update of the original article published in 1999 on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2010. General aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, arrays and fragmentation are covered in the first part of the review and applications to various structural typed constitutes the remainder. The main groups of compound that are discussed in this section are oligo and polysaccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals. Many of these applications are presented in tabular form. Also discussed are medical and industrial applications of the technique, studies of enzyme reactions and applications to chemical synthesis.

Capillary electrophoresis/mass spectrometry of APTS-labeled glycans for the identification of unknown glycan species in capillary electrophoresis/laser-induced fluorescence systems

The examination of protein glycosylation is of high importance, especially in the (bio)pharmaceutical sector. The analysis of protein glycosylation is conducted routinely in high performance by capillary electrophoresis with laser-induced fluorescence (CE/LIF) using 8-aminopyrene-1,3,6-trisulfonic acid (APTS)-labeled glycans. In this work we present an optimized capillary electrophoresis/time-of-flight mass spectrometry (CE/TOF-MS) methodology for these labeled glycans, which combines the high separation performance of CE with the high resolution, accuracy, and speed of TOF-MS for eased glycan identification. The system based on an acidic background electrolyte (BGE) provides a migration direction analogue to routine CE/LIF systems. Different BGE compositions, capillary dimensions, coatings, and instrumental parameters were tested to optimize the system with respect to separation efficiency and robustness. Subsequently, the CE/MS method optimized for acidic conditions was compared to an alkaline CE/MS method. Further, the mobilities of six APTS-labeled complex-type N-glycans were compared for both CE/MS methods and two standard CE/LIF approaches. For the acidic and alkaline BGE systems, the mobilities of sialylated glycans were shifted relative to nonsialylated glycans in comparison to common CE/LIF systems. However, in this study a straightforward unequivocal peak assignment was achieved for all unknown glycans in a medium complex glycan mixture from a fusion protein.

Capillary zone electrophoresis for the analysis of glycoforms of cellobiohydrolase

Cellobiohydrolase (CBH) is an important enzyme for the conversion of lignocellulosic biomass to ethanol. This work separated the glycoforms of CBH possessing different numbers of neutral mannoses using capillary zone electrophoresis (CZE) in a 50 mM, pH 7.5 phosphate buffer. The method analysed CBH in an intact form using a polyacrylamide coated fused silica capillary without requiring additives or labelling of the enzyme. The migration time of the major peak was found to be 21.6±0.1 min (n=3) and the approach is suitable for testing of batch-to-batch consistency of CBH. Ease-of-use, automation and speed are the other benefits due to which the use of CZE for analysing glycoforms of CBH was concluded to be ideal.