Separation and determination of glycosaminoglycan disaccharides by micellar electrokinetic capillary chromatography for studies of pelt glycosaminoglycans

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.

Capillary electrophoresis of complex natural polysaccharides

Complex natural polysaccharides, glycosaminoglycans (GAGs), are a class of ubiquitous macromolecules that exhibit a wide range of biological functions and participate and regulate multiple cellular events and (patho)physiological processes. They are generally present either as free chains (hyaluronic acid and bacterial acidic polysaccharides) or as side chains of proteoglycans (PGs; chondroitin/dermatan sulfate, heparin/heparan sulfate, and keratan sulfate) and are most often found in cell membranes and in the extracellular matrix. The recent emergence of modern analytical tools for their study has produced a virtual explosion in the field of glycomics. CE, due to its high resolving power and sensitivity, has been useful in the analysis of intact GAGs and GAG-derived oligosaccharides and disaccharides affording concentration and structural characterization data essential for understanding the biological functions of GAGs. In this review, novel off-line and on-line CE-MS and MS/MS methods for screening of GAG-derived oligosaccharides and disaccharides will be discussed.

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.

Capillary electrophoresis of highly sulfated flavanoids and flavonoids

Flavanoids and flavonoids are natural products present in our diet and known to possess multiple biological activities. Sulfated species of these natural products represent highly charged water-soluble organic molecules that possess unique biochemical properties. We describe here the first studies on capillary electrophoresis of these highly charged molecules. Fully sulfated flavanoids and flavonoids can be electrophoresed and resolved under reverse polarity at pH 3.5 using 5-10 kV in less than 20 min. In contrast, at high pH under normal polarity these species can be electrophoresed only if a pressurized capillary is employed. (+/-)-Catechin sulfate, a racemic sulfated flavanoid, was resolved into its enantiomers using 15% beta-cyclodextrin, a chiral selector, but not with alpha- or gamma-cyclodextrins. Yet, the high charge density of these molecules challenges the resolving capability of capillary electrophoresis as diastereomers (-)-epicatechin sulfate and (+)-catechin sulfate do not resolve, even in the presence of cyclodextrins or chiral positively charged amino acids. Overall, capillary electrophoresis of highly sulfated flavanoids and flavonoids is expected to be useful in rapid structure analysis of sulfated flavonoids, either synthetic or natural.

Advances in analysis of glycosaminoglycans: its application for the assessment of physiological and pathological states of connective tissues

Glycosaminoglycans are a class of biological macromolecules found mainly in connective tissues as constituents of proteoglycans, covalently linked to their core protein. Hyaluronan is the only glycosaminoglycan present under its single form and possesses the ability to aggregate with the class of proteoglycans termed hyalectans. Proteoglycans are localised both at the extracellular and cellular (cell-surface and intracellular) levels and, via either their glycosaminoglycan chains or their core proteins participate in and regulate several cellular events and (patho)physiological processes. Advances in analytical separational techniques, including high-performance liquid chromatography, capillary electrophoresis and fluorophore assisted carbohydrate electrophoresis, make possible to examine alterations of glycosaminoglycans with respect to their amounts and fine structural features in various pathological conditions, thus becoming applicable for diagnosis. In this review we present the chromatographic and electromigration procedures developed to analyse and characterise glycosaminoglycans. Moreover, a critical evaluation of the biological relevance of the results obtained by the developed methodology is discussed.

Capillary electrophoresis for the analysis of glycosaminoglycans and glycosaminoglycan-derived oligosaccharides

Glycosaminoglycans are a family of polydisperse, highly sulfated complex mixtures of linear polysaccharides that are involved in many life processes. Defining the structure of glycosaminoglycans is an important factor in elucidating their structure-activity relationship. Capillary electrophoresis has emerged as a highly promising technique consuming an extremely small amount of sample and capable of rapid, high-resolution separation, characterization and quantitation of analytes. Numerous capillary electrophoresis methods for analysis of intact glycosaminoglycans and glycosaminoglycan-derived oligosaccharides have been developed. These methods allow for both qualitative and quantitative analysis with a high level of sensitivity. This review is concerned with separation methods of capillary electrophoresis, detection methods and applications to several aspects of research into glycosaminoglycans and glycosaminoglycan-derived oligosaccharides. The importance of capillary electrophoresis in biological and pharmaceutical samples in glycobiology and carbohydrate biochemistry and its possible applications in disease diagnosis and monitoring chemical synthesis are described.

Analysis of glycosaminoglycan-derived disaccharides in biologic samples by capillary electrophoresis and protocol for sequencing glycosaminoglycans

Glycosaminoglycans are biologically significant carbohydrates which either as free chains (hyaluronan) or constituents of proteoglycans (chondroitin/dermatan sulfates, heparin, heparan sulfate and keratan sulfate) participate and regulate several cellular events and (patho)physiological processes. Capillary electrophoresis, due to its high resolving power and sensitivity, has been successfully used for the analysis of glycosaminoglycans. Determination of compositional characteristics, such as disaccharide sulfation pattern, is a useful prerequisite for elucidating the interactions of glycosaminoglycans with matrix effective molecules and, therefore, essential in understanding the biological functions of proteoglycans. The interest in the field of characterization of such biologically important carbohydrates is soaring and advances in this field will signal a new revolution in the area of glycomics equivalent to that of genomics and proteomics. This review focuses on the capillary electrophoresis methods used to determine the disaccharide pattern of glycosaminoglycans in various biologic samples as well as advances in the sequence analysis of glycosaminoglycans using both chromatographic and electrophoretic techniques.

Effects of amine modifiers on the separation of tetramethylrhodamine-labeled mono- and oligosaccharides by capillary zone electrophoresis

In this work, nine tetramethylrhodamine (TMR) labeled isomeric oligosaccharide derivatives of betaGal(1 --> 4) betaGlcNAc-O-TMR were separated by capillary zone electrophoresis coupled with laser-induced fluorescence detection. Charged species were created in situ by complexation with borate and phenylborate. Micellar separation was achieved by addition of 10 mM sodium dodecylsulfate to the running buffer. We have investigated the effects of adding a homologous series of monoamine modifiers on the separation efficiency of these oligosaccharides. The separation was significantly improved in the presence of the organic modifiers methyl- and ethylamines, but worsened in the presence of propyl- and butylamines. Possible mechanisms of the amine additives are discussed.

Separation and quantification by ion-association capillary zone electrophoresis of unsaturated disaccharide units of chondroitin sulfates and oligosaccharides derived from hyaluronan

An analytical method has been developed for assay of unsaturated disaccharides of chondroitin sulfates and of oligosaccharides (tetra- and hexasaccharides) of hyaluronan, using ion-association capillary zone electrophoresis. Samples were applied at the anode (the usual polarity), using a borate buffer modified by an ion-pairing reagent, tetrabutylammonium (TBA) phosphate, and the effect of the concentration of the ion-pairing reagent on various electrophoretic parameters (electroosmotic flow, electrophoretic mobility of products, capacity factors) was observed. Increasing concentrations of the reagent led to a decrease of zeta potential, probably due to specific adsorption of the quaternary ammonium ion onto the capillary wall. The authors propose a mechanism of separation, in which anionic borate complexes are formed and interact with TBA ion inside the capillary tube. The capillary electrophoretic system described is potentially a powerful method for specific measurement of the concentrations in joint tissues of chondroitin 4-sulfate, chondroitin 6-sulfate, and hyaluronan, whose relative abundances may vary in various diseases or after local treatments with, for example, antiinflammatory drugs, chondroprotective agents, or orthopedic implants.

A tabulated review of capillary electrophoresis of carbohydrates

This review summarizes publications on capillary electrophoresis (CE) of carbohydrates, covering almost all hitherto published papers on this topic. It is designed to be a convenient tool for the literature search by providing a comprehensive table. Since CE analysis of carbohydrates is generally complicated due to the structural diversity of carbohydrate species, an attempt is made in this table to supply detailed information on the analyzed form (underivatized or derivatized, type of derivative) and analytical conditions (capillary size, state of the inner wall, composition of the electrophoretic solution, applied voltage, detection method, etc.), for each combination of carbohydrate species to be analyzed. In addition, a brief overview is presented to help in the literature search.

A survey of methodological challenges for glycosaminoglycan/proteoglycan analysis and structural characterization by capillary electrophoresis

Proteoglycans participate and regulate several physiological processes via their glycosaminoglycan constituents. For a deeper understanding of how they interact with extracellular ligands as well as with cell bound effector molecules, the fine chemical structures of their glycosaminoglycan chains must be elucidated. Lately developed capillary electrophoretic techniques is a powerful analytical tool for the analysis of glycosaminoglycans, combining a high resolving power with sensitive detection. In this review we describe how depolymerized and intact glycosaminoglycans/proteoglycans can be characterized by capillary electrophoresis, relating these analyses to their possible biological significance. Conditions for running these separations and the detection systems for particular applications are also summarized.

Analysis of glycosaminoglycans and their oligosaccharide fragments by capillary electrophoresis

Glycosaminoglycans are high molecular mass polymers found in living tissues. They are degraded by site specific enzymes to oligosaccharide fragments. Polymers and oligomers all carry negative charge and are found as salts soluble in water. Consequently, capillary electrophoresis has come to the fore as an analytical technique in this field. This review discusses application of the technique to the chondroitin-dermatan, heparin and hyaluronan groups of polymer and the derived oligosaccharides. Direct and indirect UV detection are discussed as well as detection methods involving precolumn derivatization. Capillary electrophoresis has found use in the characterisation of heparin and in following the changes in chondroitin and hyaluronan during the onset of arthritic disease in humans. Some glycosaminoglycans have been used as asymmetric anions in the separation of enantiomers of low molecular mass compounds by capillary electrophoresis.

High-performance liquid chromatographic analysis of glycosaminoglycan-derived oligosaccharides

High-performance liquid chromatography of glycosaminoglycan (GAG)-derived oligosaccharides has been employed for the structural analysis and measurement of hyaluronan, chondroitin sulphate, dermatan sulphate, keratan sulphate, heparan sulphate and heparin. Recent developments in the separation and detection of unsaturated disaccharides and oligosaccharides derived from GAGs by enzymatic or chemical degradation are reviewed.

Separation of negatively charged carbohydrates by capillary electrophoresis

Capillary electrophoresis (CE) has recently emerged as a highly promising technique consuming an extremely small amount of sample and capable of the rapid, high-resolution separation, characterization, and quantitation of analytes. CE has been used for the separation of biopolymers, including acidic carbohydrates. Since CE is basically an analytical method for ions, acidic carbohydrates that give anions in weakly acid, neutral, or alkaline media are often the direct objects of this method. The scope of this review is limited to the use of CE for the analysis of carbohydrates containing carboxylate, sulfate, and phosphate groups as well as neutral carbohydrates that have been derivatized to incorporate strongly acidic functionality, such as sulfonate groups.

Analysis of dansyl amino acids in feedstuffs and skin by micellar electrokinetic capillary chromatography

Micellar electrokinetic capillary chromatography (MECC) using sodium dodecyl sulphate (SDS) and sodium cholate have been used for analyses of 30 dansylated (Dns) amino acids. The influences of sample preparation, Dns/amino acid ratio, sample solvent composition, and separation conditions including voltage, temperature, pH and buffer composition were investigated. Complete separations of acidic and neutral amino acids were obtained within 45 min in the SDS system. The efficiency expressed as number of theoretical plates for the applied capillary 0.52 m long were between 210,000 and 343,000, and the repeatability was very good with relative standard deviations on relative migration times between 0.09 and 0.70% and on relative normalised peak areas (RNPAs) between 0.85 and 3.41%. The linearity studies gave correlation coefficients between 0.9957 and 0.9993 for RNPAs against concentration. Detection limits were between 3 and 6 fmol or approximately 2 pg of each amino acid. Basic amino acids were separated in a MECC system using sodium cholate. Procedures and problems using Dns derivatisation for amino acids analysed by the MECC methods are described. Finally, examples of analyses of hydrolysates of real complex samples show, that this method can be applied to determine the amino acid composition of proteins in feedstuffs and skin.