Distortion of the lamellar arrangement of phospholipids by deep rough mutant lipopolysaccharide from Salmonella minnesota

详细信息    查看全文

• 作者：Edit Urbán ; A. Bóta ; B. Kocsis and K. Lohner
• 关键词：calorimetry ; cubic structures ; lipid mixtures ; phosphatidylcholine ; phosphatidylethanolamine ; phosphatidylglycerol ; X ; ray scattering
• 刊名：Journal of Thermal Analysis and Calorimetry
• 出版年：2005
• 出版时间：November 2005
• 年：2005
• 卷：82
• 期：2
• 页码：463-469
• 全文大小：457 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Sciences
  Polymer Sciences
  Physical Chemistry
  Inorganic Chemistry
  Measurement Science and Instrumentation
  
• 出版者：Akad茅miai Kiad贸, co-published with Springer Science+Business Media B.V., Formerly Kluwer Academic
• ISSN：1572-8943

文摘

The concentration dependent effects of deep rough mutant lipopolysaccharide (LPS) from Salmonella minnesota (R595) on two different phospholipid model membranes was investigated by differential scanning calorimetry and small-angle X-ray scattering (SAXS). At low concentrations of LPS the well ordered multilamellar arrangement of dipalmitoylphosphatidylcholine (DPPC) vesicles is strongly distorted resulting in a loss of positional correlation of the lipid lamellae and smaller domain sizes within the lamellae. The pre-transition of DPPC was abolished at a LPS/DPPC molar ratio of 0.1:1 and the main or chain melting transition was strongly broadened. Moreover, the enthalpy was significantly decreased and a transition was hardly detected at an equimolar mixture of LPS/DPPC. LPS also affected the lamellar arrangement of a mixture of dipalmitoylphosphatidylethanolamine (DPPE) and dipalmitoylphosphatidylglycerol (DPPG). Furthermore, a phase separation was observed for this phospholipid mixture resulting in DPPE enriched and depleted domains. Similarly to DPPC, only a weak phase transition was observed at the highest LPS concentration used (LPS/DPPE-DPPG 1:1 mol/mol). SAXS measurements showed that for both systems increasing the concentration of LPS resulted in a concomitant increase of the formation of cubic structures, which are predominant at an equimolar mixture of LPS/phospholipid. However, because of the small number of peaks it was not possible to unambiguously identify the space group of the cubic structure, complicated by the coexistence with a lamellar phase, which was particularly detectable for the LPS/DPPC mixture.