Windwarder M, Figl R, Svehla E, Mócsai RT, Farcet JB, Staudacher E, Kosma P, Altmann F. "Hypermethylation" of anthranilic acid-labeled sugars confers the selectivity required for liquid chromatography-mass spectrometry.
Anal Biochem 2016;
514:24-31. [PMID:
27640150 DOI:
10.1016/j.ab.2016.09.008]
[Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 08/11/2016] [Accepted: 09/08/2016] [Indexed: 12/15/2022]
Abstract
Analysis of the monosaccharides of complex carbohydrates is often performed by liquid chromatography with fluorescence detection. Unfortunately, methylated sugars, unusual amino- or deoxysugars and incomplete hydrolysis can lead to erroneous assignments of peaks. Here, we demonstrate that a volatile buffer system is suitable for the separation of anthranilic acid labeled sugars. It allows off-line examination of peaks by electrospray mass spectrometry. Approaches towards on-line mass spectrometric detection using reversed-phase or porous graphitic carbon columns fell short of achieving sufficient separation of the relevant isobaric sugars. Adequate chromatographic performance for isomeric sugars was achieved with reversed-phase chromatography of "hyper"-methylated anthranilic acid-labeled monosaccharides. Deuteromethyl iodide facilitates the discovery of naturally methylated sugars and identification of their parent monosaccharide as demonstrated with N-glycans of the snail Achatina fulica, where two thirds of the galactoses and a quarter of the mannoses were methylated.
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