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1983 (1)
1979 (1)
1978 (1)
1Author    H. Heithier, H.-J Galla, H. MöhwaldRequires cookie*
 Title    Fluorescence Spectroscopic and Thermodynamic Studies of Chlorophyll Containing Monolayers and Vesicles. Part I: Mixed Monolayers of Pheophytin A and Lecithin  
 Abstract    Mixed monolayers of pheophytin a and a-L-dimyristoyl lecithin (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 monolayer is established. Phase 1 exists almost exclusively of pheophytin molecules. Phase 2 exists essentially of D M L domains solubilizing pheo­ phytin in a concentration of 15 mol%. During the D M L 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. 
  Reference    Z. Naturforsch. 33c, 382 (1978); received March 15/April 3 1978 
  Published    1978 
  Keywords    Monolayers, Chlorophyll, Energy Transfer, Fluorescence Spectroscopy, Phase Transitions 
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 TEI-XML for    default:Reihe_C/33/ZNC-1978-33c-0382.pdf 
 Identifier    ZNC-1978-33c-0382 
 Volume    33 
2Author    J. Luisetti, H. Möhwald, H. J. GallaRequires cookie*
 Title    Spectroscopic and Thermodynamic Studies of Chlorophyll Containing Monolayers and Vesicles Part II: Chlorophyll a and Pheophytin a Aggregation on DMPC Vesicles  
 Abstract    Absorption and fluorescence experiments on pheophytin and chlorophyll containing lipid bilayer vesicles are reported. Pheophytin aggregates on the vesicles are established from an additional red shifted band (at 695 nm) in the absorption spectrum. These aggregates contain pheophytin in an arrangement with the molecular planes of the porphyrin rings being parallel and cover about 10% of the vesicle surface. The lipid phase dissolves pheophytin up to a molar ratio of 15% above the lipid phase transition. This solubility limit decreases hardly on solidification of the lipid. For chlorophyll a containing vesicles the aggregates are not observed in the absorption spectrum. The chlorophyll solubility is about equal to that of pheophytin. This suggests that the phase separa­ tion indicated from fluorescence measurements at temperatures below the lipid phase transition does not lead to the formation of strongly bound chlorophyll aggregates. In tro d u c tio n 
  Reference    Z. Naturforsch. 34c, 406—413 (1979); received January 25 1979 
  Published    1979 
  Keywords    Lipid Bilayers, Chlorophyll, Phase Separation, Absorption Spectroscopy, Fluorescence Spectroscopy 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-0406.pdf 
 Identifier    ZNC-1979-34c-0406 
 Volume    34 
3Author    H. H. Eithier, H. M. ÖhwaldRequires cookie*
 Title    Chlorophyll-Lipid-Interactions in Monomolecular Layers  
 Abstract    Mixed monolayers containing chlorophyll a and dim yristoyllecithin (D M L) have been investigated by simultaneous thermodynamic, fluorescence and absorption spectroscopic m ea­ surements. It has been shown that the solubility lim it o f chlorophyll a in the fluid, as well as in the solid lipid matrix, is above 20 mol%. This contrasts to previous findings for pheophytin a containing monolayers and indicates the existance o f an interaction betw een the phospholipid head group and the central Mg atom. A fluorescence decrease on solidifying the m onolayer was observed and it is suggested that it is due to an enhanced self quenching as a consequence o f the reorientation o f the porphyrin rings, accompanying the phase transition. 
  Reference    Z. Naturforsch. 38c, 1003 (1983); received June 8 1983 
  Published    1983 
  Keywords    Chlorophyll, Phase Separations, Fluorescence Spectroscopy, M onolayers, Chlorophyll-Lipid Interaction 
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 TEI-XML for    default:Reihe_C/38/ZNC-1983-38c-1003.pdf 
 Identifier    ZNC-1983-38c-1003 
 Volume    38