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Abstract
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 13CH3I or 12CH2DI generates a pair of isobaric derivatives, which have the same ominal mass. However, each methylation site introduces a mass difference of 0.002922 Da. s glycans have multiple methylation sites, the total mass difference for the isobaric pair llows separation and quantitation at a resolution of 30000 m/m. N-Linked oligosaccharidesfrom 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.