NMR-STUDY OF AOT MICROEMULSION WITH ACETONE IN THE PRESENCE OF CHLOROPHYLL-A - DISTRIBUTION OF ACETONE AND ROLE OF CHLOROPHYLL

Reverse micelles or water-in-oil microemulsions with proteins or molec ules involved in photosynthesis such as Chlorophyll a (Chl a) are inte resting as membrane mimetic systems. The multicomponent AOT/iso-octane /water-acetone system has been proposed as a carrier of photoactive Ch l a. We have focused our attention on this system to characterize its microstructure through NMR techniques. We noted a considerable structu ral modification in the AOT/iso-octane/water system caused by acetone addition. The acetone partition between the organic bulk and the micel lar phase was determined. Furthermore, a competition between Chl a and acetone to penetrate into the outer surfactant palisade was suggested . The solubilizate penetration controls the redistribution of the comp onents between the bulk and the surfactant layers. The aggregation sta te of the photoactive Chl a dihydrate dimer, proposed as a model for t he hypothesized primary donor of the PSII (photosystem II of higher pl ants) reaction center, is strongly modified when such a microemulsion is used.