Liu M S, Onji T, Snelgrove N E
Biochim Biophys Acta. 1982 Feb 15;710(2):248-51.
The effects of endotoxin (lipopolysaccharide from Salmonella minnesota Re 595) on the phase transition temperature (Tm) of various phospholipids were studied. Endotoxin had no effect on the Tm and the width of the phase transition of dipalmitoyl-sn-3-phosphatidylcholine. Endotoxin at 100 micrograms/ml increased the Tm of dipalmitoyl-sn-3-phosphatidylethanolamine by 1.1 degrees C (P less than 0.01) and narrowed the range of transition from 4.5 to 2.6 degrees C; the endotoxin-induced changes in the Tm and the transition range were abolished by the presence of 0.25 mM CaCl2. Endotoxin increased the Tm of dipalmitoyl-sn-3-phosphatidic acid by 1.1 (P less than 0.01), 1.2 (P less than 0.01), and 3.1 (P less than 0.01) degrees C at 25, 50 and 100 micrograms/ml, respectively. Furthermore, the width of phase transition of phosphatidic acid was narrowed from 6.5 to 4.0 degrees C by endotoxin at 100 micrograms/ml. The endotoxin-induced changes in the Tm and the transition range of phosphatidic acid were not affected by the presence of EDTA (1 mM) or CaCl2 (0.05-0.1 mM). These results suggest that endotoxin decreases the fluidity of negatively charged phospholipids such as phosphatidic acid and phosphatidylethanolamine. A change in the physical properties of membrane lipid bilayers induced by endotoxin may have an adverse effect on the function of biological membranes.
研究了内毒素（来自明尼苏达沙门氏菌Re 595的脂多糖）对各种磷脂相变温度（Tm）的影响。内毒素对二棕榈酰 - sn - 3 - 磷脂酰胆碱的Tm和相变宽度没有影响。100微克/毫升的内毒素使二棕榈酰 - sn - 3 - 磷脂酰乙醇胺的Tm升高1.1摄氏度（P小于0.01），并使转变范围从4.5摄氏度缩小到2.6摄氏度；0.25毫摩尔/升氯化钙的存在消除了内毒素诱导的Tm和转变范围的变化。内毒素分别在25、50和100微克/毫升时使二棕榈酰 - sn - 3 - 磷脂酸的Tm升高1.1（P小于0.01）、1.2（P小于0.01）和3.1（P小于0.01）摄氏度。此外，100微克/毫升的内毒素使磷脂酸的相变宽度从6.5摄氏度缩小到4.0摄氏度。内毒素诱导的磷脂酸Tm和转变范围的变化不受1毫摩尔/升EDTA或0.05 - 0.1毫摩尔/升氯化钙存在的影响。这些结果表明，内毒素降低了带负电荷的磷脂如磷脂酸和磷脂酰乙醇胺 的流动性。内毒素诱导的膜脂双层物理性质的变化可能对生物膜的功能产生不利影响。
