Effect of ganglioside-GM1 on the order of phosphatidylcholine-cholesterol multilamellar liposomes. A fluorescence polarization study
✍ Scribed by Robert J. Hitzemann
- Publisher
- Elsevier Science
- Year
- 1987
- Tongue
- English
- Weight
- 670 KB
- Volume
- 43
- Category
- Article
- ISSN
- 0009-3084
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✦ Synopsis
The effect(s) of bovine brain ganglioside-GM~ on the order of phosphatidylcholinecholesterol membranes were studied using steady-state fluorescence polarization (FPZ) techniques with 1,6-diphenyl-l,3,5-hexatriene (DPH) as the membrane probe. In the absence of cholesterol, GMI (30 reel%) increases both membrane order and the phase transition temperature of dipalmitoylphosphatidylcholine (DPPC) and dimyristoylphosphatidylcholine (DMPC) membranes. However, in the presence of cholesterol (0.3 or 0.5, cholesterol/phospholipid molar ratio), GM~ significantly decreases steady-state aniso~opy (r s) at temperatures above the T m for the particular phospholipid. This effect may, in part relate to a dilution of membrane cholesterol and is shared by bovine brain sphingomyelin (SM). GMx (30 mol%) increases the order of 1-palmityl-2-oleyl-PC (POPC) membranes. However, in the presence of cholesterol (0.3 molar ratio) GM~ neither increases or decreases order. Thus, in cholesterol containing artificial membranes, the effect of GMt depends on the phosphatidylcholine (PC) fatty acid composition and may not be evident from the effect of GMI on pure PC membranes.