Automated carbohydrate profiling by capillary electrophoresis: A bioindustrial approach

Capillary Electrophoresis of Mono- and Oligosaccharides

This chapter reports an overview of the recent advances in the analysis of mono- and oligosaccharides by capillary electrophoresis (CE); furthermore, relevant reviews and research articles recently published in the field are tabulated. Additionally, pretreatments and procedures applied to uncharged and acidic carbohydrates (i.e., monosaccharides and lower oligosaccharides carrying carboxylate, sulfate, or phosphate groups) are described.Representative examples of such procedures are reported in detail, upon describing robust methodologies for the study of (1) neutral oligosaccharides derivatized by reductive amination and by formation of glycosylamines; (2) sialic acid derivatized with 2-aminoacridone, released from human serum immunoglobulin G; (3) anomeric couples of neutral glycosides separated using borate-based buffers; (4) unsaturated, underivatized oligosaccharides from lyase-treated alginate.

Development and application of a high throughput carbohydrate profiling technique for analyzing plant cell wall polysaccharides and carbohydrate active enzymes

BACKGROUND

Plant cell wall polysaccharide composition varies substantially between species, organs and genotypes. Knowledge of the structure and composition of these polysaccharides, accompanied by a suite of well characterised glycosyl hydrolases will be important for the success of lignocellulosic biofuels. Current methods used to characterise enzymatically released plant oligosaccharides are relatively slow.

RESULTS

A method and software was developed allowing the use of a DNA sequencer to profile oligosaccharides derived from plant cell wall polysaccharides (DNA sequencer-Assisted Saccharide analysis in High throughput, DASH). An ABI 3730xl, which can analyse 96 samples simultaneously by capillary electrophoresis, was used to separate fluorophore derivatised reducing mono- and oligo-saccharides from plant cell walls. Using electrophoresis mobility markers, oligosaccharide mobilities were standardised between experiments to enable reproducible oligosaccharide identification. These mobility markers can be flexibly designed to span the mobilities of oligosaccharides under investigation, and they have a fluorescence emission that is distinct from that of the saccharide labelling. Methods for relative and absolute quantitation of oligosaccharides are described. Analysis of a large number of samples is facilitated by the DASHboard software which was developed in parallel. Use of this method was exemplified by comparing xylan structure and content in Arabidopsis thaliana mutants affected in xylan synthesis. The product profiles of specific xylanases were also compared in order to identify enzymes with unusual oligosaccharide products.

CONCLUSIONS

The DASH method and DASHboard software can be used to carry out large-scale analyses of the compositional variation of plant cell walls and biomass, to compare plants with mutations in plant cell wall synthesis pathways, and to characterise novel carbohydrate active enzymes.

Capillary electrophoresis/mass spectrometry relevant to pharmaceutical and biotechnological applications

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.

Capillary electrophoresis of sugar acids

This chapter illustrates the usefulness of capillary electrophoresis (CE) for the analysis of sugar acids, that is, monosaccharides and lower oligosaccharides carrying carboxylate, sulphate or phosphate groups. In order to provide a general description of the main results and challenges in the field, some relevant applications and reviews on CE of such saccharidic compounds are tabulated. Furthermore, some detailed experimental procedures are shown, regarding the CE analysis of sugar acids released upon hydrolysis of acidic polysaccharides and of glycans linked to glycoproteins. In particular, the protocols will deal with the following compounds: (i) unsaturated, underivatized oligosaccharides from lyase-treated alginate; (ii) oligosaccharides derivatized with 4-aminobenzonitrile, arising from chemical hydrolysis of alginate; (iii) sialic acid derivatized with 2-aminoacridone, released from human serum immunoglobulin G.

Conformational separation of monosaccharides of glycoproteins labeled with 2-aminoacrydone using microchip electrophoresis

The conformational separation of monosaccharides labeled with fluorescent 2-aminoacrydone (AMAC) was performed by electrophoresis on a plastic microchip with light-emitting diode confocal fluorescence detection. The AMAC-labeled five neutral monosaccharide mixture (D-glucose (Glc), D-mannose, D-galactose, L-fucose, and D-xylose) or two amino monosaccharide mixture (N-acetyl-D-glucosamine and N-acetyl-D-galactosamine) were well separated at pH 8.5 and 0.5% w/v methylcellulose of 200 mM borate buffer conditions using microchip electrophoresis. The separation was successfully performed considering the difference in stability of the complex between the hydroxyl residue of the monosaccharide and borate ions, and we found that 200 mM and pH 8.5 of borate buffer conditions were critical. High-speed separation for the neutral monosaccharides (50 s) and for amino monosaccharides (70 s) was attained at a 400 V/cm of electric field condition, showing all peak resolutions were greater than 0.9% and RSD of mobility were less than 1.9%. The detection limits of 0.86 microM for Glc and <1 microM for all other monosaccharides were enhanced with the addition of 0.5% w/v methylcellulose to the buffer. These attainments are fully compatible with conventional CE. The analysis of the subtle differences in the conformational stability and the value of the hydroxyl residue of the borate complex allowed the development of an efficient prospective tool for attaining high-resolution separation of monosaccharide mixtures having complicated and analogous conformations.