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The study of glycosylation patterns (glycomics) in biological samples is an emerging field that can provide key insights into cell development and pathology. A current challenge in the field of glycomics is to determine how to quantify changes in glycan expression between different cells, tissues, or biological fluids. Here we describe a novel strategy, quantitation by isobaric labeling (QUIBL), to facilitate comparative glycomics. Permethylation of a glycan with (13)CH 3I or (12)CH 2DI generates a pair of isobaric derivatives, which have the same nominal mass. However, each methylation site introduces a mass difference of 0.002922 Da. As glycans have multiple methylation sites, the total mass difference for the isobaric pair allows separation and quantitation at a resolution of approximately 30000 m/Delta m. N-Linked oligosaccharides from a standard glycoprotein and human serum were used to demonstrate that QUIBL facilitates relative quantitation over a linear dynamic range of 2 orders of magnitude and permits the relative quantitation of isomeric glycans. We applied QUIBL to quantitate glycomic changes associated with the differentiation of murine embryonic stem cells to embryoid bodies.
Atwood et al. (Fri,) studied this question.