Glycoscience finally comes of age

High-Throughput Analysis of the Plasma N-Glycome by UHPLC

The understanding of glycosylation alterations in health and disease has evolved significantly and glycans are considered to be relevant biomarker candidates. High-throughput analytical technologies capable of generating high-quality, large-scale glycoprofiling data are in high demand. Here, we describe an automated sample preparation workflow and analysis of N-linked glycans from plasma samples using hydrophilic interaction liquid chromatography with fluorescence detection on an ultrahigh-performance liquid chromatography (UHPLC) instrument. Samples are prepared in 96-well plates and the workflow features rapid glycoprotein denaturation, enzymatic glycan release, glycan purification on solid-supported hydrazide, fluorescent labeling, and post-labeling cleanup with solid-phase extraction. The development of a novel approach for plasma N-glycan analysis and its implementation on a robotic platform significantly reduces the time required for sample preparation and minimizes technical variation. It is anticipated that the developed method will contribute to expanding high-throughput capabilities to analyze protein glycosylation.

Characterization of the human submandibular/sublingual saliva glycoproteome using lectin affinity chromatography coupled to multidimensional protein identification technology

In-depth analysis of the salivary proteome is fundamental to understanding the functions of salivary proteins in the oral cavity and to reveal disease biomarkers involved in different pathophysiological conditions, with the ultimate goal of improving patient diagnosis and prognosis. Submandibular and sublingual glands contribute saliva rich in glycoproteins to the total saliva output, making them valuable sources for glycoproteomic analysis. Lectin-affinity chromatography coupled to mass spectrometry-based shotgun proteomics was used to explore the submandibular/sublingual (SM/SL) saliva glycoproteome. A total of 262 N- and O-linked glycoproteins were identified by multidimensional protein identification technology (MudPIT). Only 38 were previously described in SM and SL salivas from the human salivary N-linked glycoproteome, while 224 were unique. Further comparison analysis with SM/SL saliva of the human saliva proteome, revealed 125 glycoproteins not formerly reported in this secretion. KEGG pathway analyses demonstrated that many of these glycoproteins are involved in processes such as complement and coagulation cascades, cell communication, glycosphingolipid biosynthesis neo-lactoseries, O-glycan biosynthesis, glycan structures-biosynthesis 2, starch and sucrose metabolism, peptidoglycan biosynthesis or others pathways. In summary, lectin-affinity chromatography coupled to MudPIT mass spectrometry identified many novel glycoproteins in SM/SL saliva. These new additions to the salivary proteome may prove to be a critical step for providing reliable biomarkers in the diagnosis of a myriad of oral and systemic diseases.

Two-dimensional HPLC separation with reverse-phase-nano-LC-MS/MS for the characterization of glycan pools after labeling with 2-aminobenzamide

N-Glycans, O-glycans, glycolipid glycan chains, and other oligosaccharide pools released from various natural sources often represent very complex mixtures. Various tandem mass spectrometric techniques may be applied to glycan pools, resulting in valuable structural information. For a very detailed analysis of these pools, however, the following approach may be preferable: In a first step, reducing-end oligosaccharides are labeled with the aromatic tag 2-aminobenzamide (2-AB). The 2-AB glycans are separated by analytical-scale, normal-phase (NP)-HPLC (first dimension) and peak-fractionated using fluorescence detection. Peak fractions are analyzed by nano-LC-ESI-IT-MS/MS using a conventional reverse-phase (RP) nanocolumn (second dimension). Chromatography may be monitored by measuring the UV absorbance of the AB tag. Tandem mass spectrometry may be performed on deprotonated species (negative-ion mode), on proton adducts, as well as on sodium adducts (positive-ion mode). This approach has the following particular advantages: (1) the combination of the two HPLC dimensions usually separates isobaric species from each other, thereby allowing the tandem mass spectrometric characterization of individual glycan structures; (2) the AB-mass tag helps with the unambiguous assignment of fragment ions; (3) the second-dimension RP-nano-LC-MS/MS analyses can be performed in many mass spectrometric laboratories, as only standard equipment is needed. Alternatively, for a less in-depth characterization of complex glycan pools, the RP-nano-LC-MS/MS technique may be used as a stand-alone technique. In conclusion, the presented methods allow the detailed mass spectrometric characterization of complex N-glycan pools released from various biological sources.

A sugar rush for developmental biology

The EMBO Workshop on Glycoscience and Development, organised by Philippe Delannoy, Yann Guérardel, Tony Merry and Jean-Claude Michalski, was held in the picturesque, contemplative environment of Les Minimes, a converted seventeenth century Flemish convent in Lille, France, in December 2007. A cross-section of researchers, both confirmed `glycomaniacs' and those newer to the field, discussed and debated recent advances in the field of glycobiology. Presentations ranged from the clinical applications of glycobiology to novel approaches for unravelling carbohydrate biosynthesis in developmental settings and models, such as the fruit fly, nematode and zebrafish.