Characterization of complex, heterogeneous lipid A samples using HPLC-MS/MS technique I. Overall analysis with respect to acylation, phosphorylation and isobaric distribution.

Sándor, Viktor and Dörnyei, Ágnes and Makszin, Lilla and Kilár, Ferenc and Péterfi, Zoltán and Kocsis, Béla and Kilár, Anikó (2016) Characterization of complex, heterogeneous lipid A samples using HPLC-MS/MS technique I. Overall analysis with respect to acylation, phosphorylation and isobaric distribution. JOURNAL OF MASS SPECTROMETRY, 51 (11). pp. 1043-1063. ISSN 1076-5174

Text J_Mass_Spectrom_2016_51_1043_1063_u.pdf Restricted to Repository staff only Download (2MB) | Request a copy

Abstract

We established a new RP-HPLC method combined with ESI-Q-TOF tandem mass spectrometry for the simultaneous determination and structural characterization of different lipid A types in bacteria (Escherichia coli O111, Salmonella adelaide O35, Proteus morganii O34) showing serological cross-reactivity. The complex lipid A mixtures (obtained by simple extraction and acid hydrolysis of the outer membrane lipopolysaccharides) were separated and detected without phosphate derivatization. Several previously unidentified ions were detected, which differed in the number and type of acyl chains and number of phosphate groups. In several cases, we observed the different retention of isobaric lipid A species, which had different secondary fatty acyl distribution at the C2' or the C3' sites. The fragmentation of the various, C4' monophosphorylated lipid A species in deprotonated forms provided structural assignment for each component. Fragmentation pathways of the tri-, tetra-, penta-, hexa-, and hepta-acylated lipid A components and of the lipid A partial structures are suggested. As standards, the hexa-acylated ion at m/z 1716 with the E. coli-type acyl distribution, and the hepta-acylated ion at m/z 1954 with the Salmonella-type acyl distribution were used. The results confirmed the presence of multiple forms of lipid A in all strains analyzed. In addition, the negative-ion mode MS permitted efficient detection for non-phosphorylated lipid A components, too. This article is protected by copyright. All rights reserved.

Actions (login required)

Edit Item