X. Hronowski, Yan Wang, Z. Sosic
Jul 6, 2020
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Influential Citations
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Journal
Analytical chemistry
Abstract
2-aminobenzoic acid (2-AA) is widely used as a labeling reagent to derivatize released N-glycans at their free reducing terminus by reductive amination. 2-AA labeled glycans have increased mass spectrometric sensitivity for their identification and enable fluorescence-chromatography based glycan quantification. Drawbacks are that the labeling process is labor intensive and time consuming. Clean-up of labeled glycans via removal of excess of labeling reagents often leads to sample losses. Here, we report use of 2-AA for labeling N-glycans on a MALDI target through nonreductive amination, while simultaneously functioning as a matrix in MALDI-MS glycan analysis. Coupling 2-AA to glycans results in significant increases of glycan anionic signals as compared to that using traditional 2,5-dihydroxybenzoic acid (2,5-DHB) matrix. The on-MALDI-target sample preparation is a single-step protocol with high derivatization efficiency. It is also noticed that 2-AA labeled glycan generated dominant molecular anions with much fewer and low-intensity sodium adducts, and therefore greatly simplified glycan profiles. We further explored its application in N-glycan profile of a biotherapeutic monoclonal antibody and was able to achieve sensitive glycan identification at low microgram level of glycoprotein. This 2-AA on-MALDI-target glycan derivatization eliminates tedious sample preparation and avoids sample loss. It is generally applicable for other applications (e.g. Glycomics), where limited amounts of glycoproteins are available for analysis.