استخراج و جداسازی LPS غشاء خارجی H.pylori با استفاده از SDS-PAGE و رنگ آمیزی نیترات نقره

Background: Helicobacter pylori (H. pylori) is one of the major causes of peptic ulcer, gastritis and gastric cancer. This bacterium has a special lipopolysaccharide (LPS), which is responsible for its pathogenesis and its high resistance against gastric acid and escape from the human immune system. This property makes it a target for further research and diagnostic goals. In this study, the extraction of the LPS and separation from the outer membrane is required. Methods: The LPS was extracted from the outer membrane, or envelope, of H. pylori obtained from patients suffering from gastritis, gastric ulcer and gastric cancer. LPS extraction was performed using the proteinase K method. SDS-PAGE and silver staining were applied to investigate the electrophoretic pattern of the LPS. This pattern was compared with that of E. coli serotype O111:B4 and Salmonella serotype ATCC 14028. Results: The extracted LPS has a ladder-shaped electrophoretic pattern and the bands are located in three groups: high, medium and low molecular weights. Conclusion: The distribution of the bands of the ladder-shaped electrophoretic pattern is caused by the different number of oligosaccharide chains associated with the LPS. The high molecular weight bands represent S-LPS and the low molecular weight bands represent the R-LPS, which lacks the O-chain.