Mass Spectrometric Analysis of Carbohydrate Molecules with Signal Enhancing Tags
Date Issued
2010
Date
2010
Author(s)
Chen, Ying-Chu
Abstract
Carbohydrates are the most abundant and structurally diverse natural products.They possess a large number of functionalities in biology. Nevertheless, their structural
complexities hamper the detailed understanding of their roles. Mass spectrometry has been proved to be a precise, high sensitive and fast tool for carbohydrates structural
analysis. Due to the low ionization efficiency of carbohydrates, derivatization has frequently used to improve the detection efficiency of oligosaccharides in mass spectrometry.
Recently, a direct conjugation method by forming a robust amide bond between amines and the reducing end of aldose was developed by our laboratory. Therefore, we utilized this oxidative amidation process for derivitizing oligosaccharide with aralkylamine and peptides containing arginine or phenylalanine moieties. Initially, maltotriose (G3) was modified with various amine tags for a rapid screening of their effects in amplification of the signal intensity in MALDI– and ESI–MS. The chosen signal enhancing tags were subsequently used to modify maltoheptaose (G7) for further sensitivity studies. Our results showed that these oligosaccharide derivatives indeed enhanced the detection sensitivity in mass spectrometry, particularly up to 100-fold enhancement in MALDI-MS.
On the other hand, tagging G7 or tetrasialic acid (SA4) with a new designed diamine tag through the iodine-promoted oxdative condensation was conducted. This diamine tag contained an arginine moiety, and this derivatization method was useful for not only aldoses but also ketoacids to show significant signal enhancement in both ESI–and MALDI–MS. Under the reaction conditions, tetrasialic acid also underwent intramolecular lactonization to give a derivative that exhibit more than 450-fold signal enhancement in MALDI–MS.
Subjects
carbohydrates
derivatization
signal enhancement
mass spectrometry
Type
thesis
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