Aggregation/disaggregation of chlorophyll a in model phospholipid—detergent vesicles and micelles

The photosynthetic pigments of higher plants exist in complex oligomeric states, which are difficult to study in vivo . To investigate aggregation processes of chlorophyll a (Chl a ), we used an in vitro reconstitution procedure, with this pigment incorporated into liposomes of 1,2-dimyristoyl- sn -...

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Published inPhotochemical & photobiological sciences Vol. 13; no. 6; pp. 907 - 916
Main Authors Correia, Raquel F., Viseu, M. Isabel, Andrade, Suzana M.
Format Journal Article
LanguageEnglish
Published Cham Springer International Publishing 01.06.2014
Subjects
Absorption
Biochemistry
Biomaterials
Chemistry
Chlorophyll - chemistry
Detergents - chemistry
Dimyristoylphosphatidylcholine - chemistry
Fluorescence
Liposomes
Micelles
Microscopy, Fluorescence
Models, Chemical
Phospholipids - chemistry
Physical Chemistry
Plant Sciences
Quaternary Ammonium Compounds - chemistry
Spectrometry, Fluorescence
Time Factors
Ultraviolet Rays
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Summary:The photosynthetic pigments of higher plants exist in complex oligomeric states, which are difficult to study in vivo . To investigate aggregation processes of chlorophyll a (Chl a ), we used an in vitro reconstitution procedure, with this pigment incorporated into liposomes of 1,2-dimyristoyl- sn -glycero-3-phosphocholine (DMPC), micelles and pre-micelle media of the detergent n -dodecyltrimethylammonium chloride (DTAC), and mixed, spontaneous, DMPC—DTAC vesicles and micelles. Chl a oligomers were characterized by UV-visible absorption, steady-state and time-resolved fluorescence, and fluorescence lifetime imaging microscopy. Equivalent diameters of the colloidal structures were obtained by fluorescence correlation spectroscopy. In DMPC liposomes and DMPC—DTAC vesicles and micelles, three fluorescence lifetimes indicated the coexistence of Chl a monomers (≈5 ns) and oligomers (≈1t–2 to ≈0.1 ns). The increase in DTAC amount, in the mixed system, induces a progressive solubilization of DMPC liposomes (from vesicles to micelles) and simultaneous disruption of Chl a aggregates; in pure DTAC micelles, mostly monomers were found. The present work aims for a better understanding of chlorophyll—chlorophyll (Chl—Chl), Chl—lipid, and Chl—detergent interactions in spontaneous colloidal micro- and nanostructures.
ISSN:1474-905X
1474-9092
DOI:10.1039/c3pp50419k