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NACE–ESI‐MS/MS method for separation and characterization of phosphorylation and acylation isomers of lipid A
Author(s) -
Sándor Viktor,
Berkics Balázs Viktor,
Kilár Anikó,
Kocsis Béla,
Kilár Ferenc,
Dörnyei Ágnes
Publication year - 2020
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.201900251
Subject(s) - chemistry , acylation , lipid a , chromatography , triethylamine , lipidomics , phosphorylation , mass spectrometry , organic chemistry , biochemistry , lipopolysaccharide , catalysis , medicine , endocrinology
Lipid A represents a heterogeneous group of bacterial outer membrane phosphoglycolipids, which play a major role in the pathogenesis of Gram‐negative sepsis. The number and position of phosphoryl and acyl groups in lipid A molecules are key structural determinants in their bioactivities. In this study, a NACE–ESI‐MS/MS method was developed for the simultaneous analysis of lipid A isomers possessing a different degree of phosphorylation and acylation. Various C4’‐ and C1‐monophosphorylated lipid A isobars, as well as acylation isomers, were baseline separated within 43 min in a separation medium of methanol/dichloromethane/triethylamine/acetic acid 60:40:1.08:0.36 (v/v/v/v). Both normal and reverse CE polarities could be applied for proper detection of the analytes owing to the combination of a suction effect caused by the nebulizer gas at the outlet end of the capillary and external pressure applied on the inlet vial. The separated lipid A species could be identified unequivocally by their characteristic fragmentation patterns through CID performed in both negative‐ and positive‐ionization modes. The uniqueness of the NACE–ESI‐MS/MS method lies in its simplicity and reliability for proving the phosphorylation isomerism (C1 or C4’) and acylation pattern of native lipid A species or those designed for therapeutic applications.