CD BioGlyco has rich experience in the purification and structural analysis of lipopolysaccharides (LPSs), and we provide competitively advanced technology platforms. We have confidence to be your essential research assistant in the field of glycobiology.

Background

LPSs are located on the cell surface of almost all Gram-negative bacteria, such as Escherichia coli, Klebsiella, Salmonella, Pseudomonas, etc. Its basic structure consists of three parts: lipid A, core oligosaccharides and repeating polysaccharides called O-antigens. All parts of LPS show inherent biological and chemical heterogeneity. Amphiphilic LPS molecules form aggregates in aqueous solutions, although sodium dodecyl sulfate (SDS), ethylenediaminetetraacetic acid (EDTA) or proteins (such as hemoglobin) can be used to destroy the structure of the aggregates. The diversity of molecular species still challenges the complete LPS structure analysis.

The most conserved part of LPS is lipid A. Changes in lipid A structure of lipid A, namely acylation, phosphorylation and glycosylation, will greatly affect the endotoxin activity. Lipid A may cause the mammalian immune system to lose control and trigger the biosynthesis of abnormal amounts of inflammatory mediators (such as interleukin 1), which may lead to septic shock. The carbohydrate portion of endotoxin is associated with serotype-specific immunogenicity, which is due to a single O antigen determinant or core oligosaccharide epitope. The relationship between the structure of endotoxin and its biological activity triggers the interest of more researchers to study in-depth the lipopolysaccharide structure.

Fig 1. Structure lipopolysaccharide from Gram-negative bacteria (Lin, T.L.; et al. 2020)

Key Technologies

The analytical platform engineered for LPS scrutiny is constructed upon an amalgamation of validated and proprietary methodologies dedicated to the extraction, refinement, and structural elucidation of these intricate amphiphilic molecules. Our strategy is meticulously calibrated according to both bacterial serotype and specific experimental aims, thereby guaranteeing superior outcomes. Central to our technological repertoire are the following components:

We harness a spectrum of extraction protocols engineered to maximize both yield and purity. In the case of rough phenotypes deficient in the O-antigen domain, specialized approaches such as diethyl ether extraction are utilized for targeted molecular isolation. Our laboratory has further devised and substantiated a refined propanol-alkaline hydrolysis technique, which attains exceptional purity while mitigating hazards associated with classical protocols.

Attainment of ultrapure preparations necessitates implementing sequential purification stages. This encompasses enzymatic treatment using a combination of proteinase K, ribonuclease, and deoxyribonuclease I to eradicate residual protein and nucleic acids. Subsequent steps involve extensive dialysis and high-resolution chromatographic separations aimed at expelling lingering reagents and further refining the LPS isolate.

A battery of advanced analytical instruments is deployed to furnish exhaustive structural insights into the purified lipopolysaccharide. Modalities such as high-performance liquid chromatography (HPLC) evaluate sample homogeneity and purity, while mass spectrometric (MS) analysis delineates exact molecular mass and constitutive details—particularly within the conserved lipid A moiety. Such resolution permits the discernment of fine structural variances frequently overlooked by conventional assays.

Precision-Mapped LPS: From Lipid A to O-Antigen.

At CD BioGlyco, we use the following methods for the structure analysis of lipopolysaccharide.

• Analysis of O-antigens and core oligosaccharides

Purification and size determination by FPLC, SEC, HPAEC and RPC; monosaccharide composition by GC-MS, GC-FID and GC-CI; glycosyl linkage of neutral and acidic sugars by partially methylated alditol acetates (PMAA); elucidate glycosyl sequence and structure by NMR, MALDI-TOF MS, MS/MS and ESI-MS.

• Analysis of lipid A

Purified by liquid-liquid extraction and HPLC; molecular weight and structure were clarified by MALDI-TOF MS, MS/MS, ESI-MS and NMR.

Workflow

• LPS Extraction

Clients' bacterial cells are subjected to a carefully selected extraction method tailored to the strain and LPS type (S-LPS or R-LPS). This step releases the LPS from the bacterial outer membrane.

• Enzymatic and Chemical Purification

The crude LPS extract is subjected to a multi-step purification process. This includes enzymatic digestion to remove protein and nucleic acid contaminants, followed by chemical treatments and phase separations to isolate the purified LPS fraction.

• Final Purification and Quantification

The extracted LPS undergoes final purification using advanced techniques like column chromatography. The final product is then precisely quantified and prepared for structural analysis.

• Structural Analysis

The purified LPS is analyzed using our high-resolution analytical platform. This includes a battery of tests to confirm purity and homogeneity, and in-depth MS to provide a detailed structural map of the molecule, including the Lipid A, core oligosaccharide, and O-antigen components.

Case Study

Background

LPS is a complex macromolecular structure composed of a variable O-antigen polysaccharide, a core oligosaccharide, and a conserved, biologically active Lipid A anchor. Characterizing the exact chemical configuration of LPS, specifically the precise glycosidic linkage positions of the carbohydrate backbone and the microheterogeneity (heterogeneity in acylation and phosphorylation patterns) of Lipid A, is critical for understanding bacterial pathogenesis and evaluating endotoxin-induced immune responses. However, because these structures are highly branched and variable, achieving definitive structural elucidation requires advanced, multi-dimensional mass spectrometry workflows.

Our Solution

CD BioGlyco deployed an integrated analytical strategy combining PMAA linkage analysis and high-resolution MALDI-TOF/TOF MS for full-surface structural fingerprinting.

• PMAA Linkage Profiling: To determine the exact bonding positions of the carbohydrate chain, samples were completely permethylated via an optimized DMSO-iodomethane matrix, hydrolyzed using trifluoroacetic acid (TFA), reduced with sodium borodeuteride, and converted into volatile PMAA derivatives. These derivatives were analyzed using GC-MS equipped with a Restek-5ms capillary column.
• Targeted Lipid A Isolation & Characterization: Lipid A domains were selectively liberated from the hydrophilic polysaccharide chain via precisely controlled mild acid hydrolysis using 1% aqueous acetic acid. The isolated hydrophobic lipid A fraction was crystallized with optimized matrices (such as 3-aminoquinoline/super-DHB) and subjected to high-precision MALDI-MS operating in negative reflectron mode to maximize the ionization of naturally phosphorylated species.

Results

The combined dual-method analysis yielded a high-fidelity structural blueprint of the bacterial LPS architecture:

• Glycosidic Linkage Footprinting: GC-MS evaluation of the PMAA derivatives successfully resolved the retention times and characteristic electron ionization mass fragmentation patterns (EI-MS). The assay definitively identified and mapped the core monosaccharide framework, specifically validating the pyranose configurations and linkage positions for Man and GlcNAc.

Fig.2 The chromatogram of PMAA analysis. (CD BioGlyco)

Fig.3 The mass fragmentation patterns (32.269 min). (CD BioGlyco)

Table 1 The data of the PMAA analysis. (CD BioGlyco)

• Lipid A Acylation & Phosphorylation Profiling: Negative-mode MALDI-MS characterization successfully uncovered distinct molecular ion profiles that mapped the dynamic fatty acid and phosphate landscapes. For instance, the reference monophosphoryl lipid A demonstrated clear molecular ions at m/z 1716, 1506, and 1280, corresponding to hexa-acylated, penta-acylated, and tetra-acylated species, respectively. In contrast, the lipid A isolated from the E. coli strain revealed a predominantly diphosphoryl hexa-acylated architecture.

Fig.4 MALDI-TOF-MS spectrum of lipid-A. (CD BioGlyco)

This comprehensive structural analysis workflow allowed the client to successfully bridge the gap between LPS chemical composition and its biological functionality. By delivering precise details on both the carbohydrate chain connectivity and lipid A microheterogeneity, our service provided invaluable molecular insights that directly accelerated the client's structural biology research and advanced vaccine adjuvant characterization programs.

Publication Data

Applications

• Study on the correlation between structure and biological activity of lipopolysaccharide
• Research on antibodies and inhibitors of lipopolysaccharide-related diseases (such as sepsis)
• Lipopolysaccharide pathogenic mechanism research
• Development of lipopolysaccharide preparations

Advantages

• We provide in-depth structural analysis using state-of-the-art analytical tools.
• Our expertise allows for the assessment of structural heterogeneity, which is critical for understanding biological activity.
• Our expertise with various extraction and purification techniques allows us to select the optimal approach for your specific bacterial strain and research objective.

Frequently Asked Questions

Associated Services

The intricate architecture of LPS, particularly its polysaccharide components like the O-antigen and core oligosaccharide, underscores the critical importance of detailed structural elucidation in understanding its biological functions and interactions. This complexity highlights the need for advanced analytical techniques, which are equally vital for characterizing other clinically and industrially significant polysaccharides. Specialized Polysaccharide Analysis Services, such as Glycogen Analysis Service, Glucomannan Analysis Service, and Chitin/Chitosan Analysis Service, provide the essential expertise and technological precision required to decode the diverse structures and functions of these important biopolymers.

CD BioGlyco has first-class technology and well-trained technicians, and can provide customers with comprehensive and reliable analysis services for lipopolysaccharide research. We will continue to raise the standard to meet customers' glycobiology research needs.

Customers can contact our employees directly and we will respond promptly. If you are interested in our services, please contact us for more detailed information.

References

1. Lin, T.L.; et al. Like cures like: pharmacological activity of anti-inflammatory lipopolysaccharides from gut microbiome. Frontiers in Pharmacology. 2020, 11: 554. (Open Access)
2. Caroff, M.; Novikov, A. Lipopolysaccharides: structure, function and bacterial identifications. OCL. 2020, 27: 31. (Open Access)