Correia RF, Viseu MI, Andrade SM. Aggregation/disaggregation of chlorophyll a in model phospholipid-detergent vesicles and micelles.
Photochem Photobiol Sci 2014;
13:907-16. [PMID:
24715103 DOI:
10.1039/c3pp50419k]
[Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
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 (≈1-2 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.
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