Fluorescence Spectroscopic and Thermodynamic Studies of Monolayers Containing Pheophytin a and Lecithin
Abstract Mixed monolayers of pheophytin a and L‐α‐dimyristoyllecithin (DML) are investigated on the water surface. The studies gain their special value from the simultaneous measurement of surface pressure and fluorescence intensity as a function of the covered area per molecule. A phase separation...
| Published in: | Berichte der Bunsengesellschaft für physikalische Chemie |
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| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Wiley
1978
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1002/bbpc.19780820929 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fbbpc.19780820929 https://onlinelibrary.wiley.com/doi/pdf/10.1002/bbpc.19780820929 |
| Summary: | Abstract Mixed monolayers of pheophytin a and L‐α‐dimyristoyllecithin (DML) are investigated on the water surface. The studies gain their special value from the simultaneous measurement of surface pressure and fluorescence intensity as a function of the covered area per molecule. A phase separation in the liquid state of the mono‐layer is established. Phase (1) exists almost exclusively of pheophytin molecules. Phase (2) exists essentially of DML domains solubilizing pheophytin in a concentration of 15 mol‐%. During the DML main transition the pheophytin solubility decreases to about 2 mol‐%, the excess pheophytin being precipitated within the surface layer. During the pheophytin main transition an ordered structure below the surface layer is formed. A stabilizing interaction between the pheophytin domains and their environment is observed and discussed. A sharp fluorescence change at a pressure below 0.5 dyn/cm indicates another phase transition. It very probably involves an unwrapping of pheophytin from water molecules. |
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