COLL 372 |
| Hans-Joachim Galla, Stefan Malcharek, Christian Schachtrupp, and Friedrich Spener. Institut fuer Biochemie, Westfaelische Wilhelms-Universitaet Muenster, Muenster, Germany |
| Fluorescence intensity distribution analysis of domains formed in artificial surfactants containing phosphatidylcholin and phosphatidylglycerol in a 8:2 molar ratio and surfactant protein-C (0.4 mol%) was interpreted by the formation of multilayer structures formed underneath the monolayer at the air water interface under compression. Scanning force microscopy (SFM) and raster electron microscopy of LB-films transferred in the plateau region of the corresponding isotherm at 54 mN/m proved the formation of stacks of double layers. These domains were analysed chemically by secondary ion mass spectrometry (TOF-SIMS) quantitatively determining the spatially resolved composition of the domains, which are drastically enriched in SP-C together with the negatively charged DPPG. In a very new approach using fluorescence microscopy and SFM we showed that these structures are also present at curved surfaces. Air bubbles of less then 1 mm diameter were formed on microscopic hydrophobic gold squares. Surfactant was spread on the surface of the bubble. Fluorescence as well as SFM measurements on the bubble surface showed the same domain topology observed at the planar surfaces. It remains to be answered whether these bilayer protrusions are of relevance for biological systems. We investigated lavage material from mice with disturbed fatty acid metabolism. Since the lung surfactant contains about 90 weight percent lipids endogenous and exogenous fatty acids are necessary for the synthesis of the lung surfactant. Fatty-acid-binding-proteins (FABPs) are required to transport and provide these fatty acids to the lipid metabolism. The isolated hydrophobic extracts from epidermal ( E ) and heart ( H ) FABP knock-out mice exhibit a decreased lipid/protein ratio. Film balance measurements and scanning force microscopy (SFM) studies using the lipid/protein mixtures from knock-out mice demonstrate a dysfunction in the formation of multilayers at the air water interface. In fluorescence microscopy micrographs we were able to show a corresponding difference in size and structure of domains using lavage extracts obtained from wildtype mice compared to knock-out mice. In conclusion we demonstrate that lipid metabolism is strongly correlated to the structural organisation and proper function of the alveaolar surfactant. |
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Surface and Colloid Chemistry Award Symposium Honoring Joseph Zasadzinski
8:10 AM-12:10 PM, Wednesday, March 31, 2004 Marriott -- Orange County 3, Oral
Division of Colloid and Surface Chemistry |