Interplay of Permanent Charge and Hydrophobicity in the Electrospray Ionization of Glycans

Abstract

The analysis of N-linked glycans by mass spectrometry (MS) has been characterized by low signal-to-noise ratios and high limits of detection due to their hydrophilicity and lack of basic sites able to be protonated. As a result, every step in glycan sample preparation must be thoroughly optimized in order to minimize sample loss, contamination, and analytical variability. Importantly, properties of glycans and their derivatized counterparts must be thoroughly studied in order to exploit certain characteristics for enhancing MS analysis. Herein, the effectiveness of the incorporation of a permanent charge is studied and determined to hamper glycan analysis. Also, a procedure for glycan hydrazone formation is optimized and outlined where a large number of variables were simultaneously analyzed using a fractional factorial design (FFD) in order to determine which conditions affected the reaction efficiency of the hydrazone formation reaction. Finally, the hydrophobic tagging of glycans is shown to be a viable opportunity to further increase the ion abundance of glycans in MS.

A facile method for cellular N-glycomic profiling by matrix-assisted laser desorption/ionization mass spectrometry

“…Additionally, even though permethylation has been shown to increase the glycan abundance but are not useful with larger glycans due to incomplete reaction dispersing the glycan signal across several different m/z channels. 18 Lattová et al have reported an efficient method for N-glycan analysis which involved one-step organic extraction in prior to Peptide-N-Glycosidase F (PNGase F) deglycosylation.…”

Recent Advancement of Chemical Derivatization and Its Applications to High Sensitive Analysis of Peptide in Mass Spectrometry

“…Muddiman' group further systematically discussed the interplay of permanent charge and hydrophobicity in ionization of glycan. The results demonstrated that the introduction of hydrophobic tags could increase the ESI response of glycans, while introduction of a permanent charge rendered the labeled glycans more solvated in electrospray droplet, resulting in a decrease in ESI response [47] . Therefore, several of neutral, hydrophobic tags, including 2-phenylacetohydrazide (GPN), 3-phenylpropanehydrazide (GPN2), 4-phenylbutanehydrazide (GPN3), 5-phenylpentanehydrazide (GPN4) and 4-phenethylbenzohydrazide (phenyl2-GPN), were further synthesized, of which phenyl2-GPN derivatization obviously increased the ionization of glycan.…”

Tagging saccharides for signal enhancement in mass spectrometric analysis

“…[14] Most aromatic compounds are good candidates for tagging saccharides because such derivatives not only increase hydrophobicity but also are easily detected by their optical properties (e.g. UV absorptions and fluorescence emission) during chromatography or electrophoresis.…”