3-Aminoquinoline Acting as Matrix and Derivatizing Agent for MALDI MS Analysis of Oligosaccharides

Abstract

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a widely used method in oligosaccharide analysis. Underivatized oligosaccharides are not well-suited for that purpose due to their low ionization efficiency; however, derivatization requires tedious sample purification steps which may lead to sample losses, thereby decreasing its benefit. On-target derivatization performed by the matrix 3-aminoquinoline does not require such purification and yields Schiff bases which can be measured in positive and negative ion mode from one single spot. In negative ion mode, spectra from anionic adducts of the derivatives can be acquired from 1 fmol of oligosaccharide. Furthermore, postsource decay (PSD) fragmentation in positive and negative ion mode is enhanced, providing information on oligosaccharide sequence, linkage, and branching. Optimization of reaction conditions and matrix solution led to a complete and reproducible derivatization for all tested standard oligosaccharides. Finally, the method was applied to trifucosyllacto-N-hexaose and trifucosyl-para-lacto-N-hexaose, two isomers occurring in human breast milk samples, which were easily identified and distinguished.

Sensitive and Structure-Informative <i>N</i>-Glycosylation Analysis by MALDI-MS; Ionization, Fragmentation, and Derivatization

“…It should be noted that contamination by boron compounds, which is a major component of reducing reagents, can cause the unintended formation of multiple boron adducts in glycans, decreasing analytical performance in MALDI-MS. 21) As a sensitive and MALDI-suited labeling method, Rohmer et al reported on the use of a solid matrix 3-aminoquinoline (3-AQ) as a labeling reagent. 22) is reaction takes place on a MALDI target, and 3-AQ plays the role not only of a labeling reagent but also of a MALDI matrix; hence, a puri cation step is no longer required. is method is categorized as nonreductive amination, and therefore contamination by boron compounds can be completely avoided.…”

N-(1-Naphthyl) Ethylenediamine Dinitrate: A New Matrix for Negative Ion MALDI-TOF MS Analysis of Small Molecules

“…The samples were extensively diluted with 50:50 methanol/water solution to desired concentrations prior to analysis. Taking the analysis of glucose as an example, we defined a positive detection of nitrate-attached glucose ions based on the peak detection criteria of above a signal-to-noise (S/N) to 3 ( Figure 3) [29,[37][38][39]. Experimentally determined limit of detections (LODs) for the above mentioned analytes were listed in the Supplementary Table 1.…”

“…Although low fragmentation of matrix ions can be attained with these techniques, several experimental factors, including surface morphology and laser fluence, need to be optimized simultaneously to achieve a reliable analysis. Recently, conjugated amino aromatic systems have been explored as matrixes for negative ion MALDI [18][19][20][21][22][23][24]. For example, 9-aminoacridine was used as an efficient matrix to analyze low molecular compounds [18,20,21].…”

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

“…By the further derivatization of neutral oligosaccharide fraction from milk of a woman, total 22 oligosaccharides were identified, among which 21 had novel structures [50] . Qian et al [51] used 1-(4-cyanophenyl)-4-piperidinecarbohydrazide (CPH) for the derivatization of oligosaccharides; the detection sensitivity of maltoheptaose was increased by 10-fold via MALDI-TOF MS. With 3-aminoquinoline as matrix and derivatization reagent, 1 fmol of oligosaccharides were detected by Karas and co-workers via negative ion mode MALDI-TOF MS [52] . Kaneshiro et al [53] further applied 3-aminoquinoline to the derivatization of glycan.…”