Document Detail

Interaction of pyridinium bis-retinoid (A2E) with bilayer lipid membranes.
MedLine Citation:
PMID:  17070694     Owner:  NLM     Status:  MEDLINE    
The accumulation of lipofuscin granules within the retinal pigment epithelium (RPE) cells is correlated with the progression of age-related macular degeneration. One of the fluorophores contained in lipofiscin granules is pyridinium bis-retinoid (A2E). To test its membrane-toxic effect, the interaction of A2E with bilayer lipid membranes (BLM) was studied. The incorporation of charged A2E molecules into the membranes has been detected as a change of either zeta-potential of multilayer liposomes or boundary potential of BLM. It was shown that the presence of up to 25mol% of A2E did not destabilize the bilayers made of saturated phosphatidylcholine (PC). However, the destabilizing effect became very significant when BLM contained negatively charged lipids such as cardiolipin or phosphatidylserine. The electrical breakdown measurements revealed that the A2E-induced decrease of BLM stability was primarily associated with the growing probability of lipid pore formation. It was found from the measurements of boundary potential of BLM that exposure of A2E to light initiates its transformation into at least two products. One of them is epoxy-A2E, which, being hydrophilic, moves from the membrane into water solution. The other product is a non-identified hydrophobic substance. Illumination of A2E-containing BLM made from unsaturated PC by visible light caused the membrane damage presumably due to oxidation of these lipids by singlet oxygen generated by excited A2E molecules. However, this effect was very weak compared to the effect of known photosensitizers. The illumination of BLM with A2E also leads to the damage of gramicidin incorporated into the membrane, as was detected by measuring the conductance of channels formed by this peptide.
V S Sokolov; E A Sokolenko; A V Sokolov; A E Dontsov; Y A Chizmadzhev; M A Ostrovsky
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-10-27
Journal Detail:
Title:  Journal of photochemistry and photobiology. B, Biology     Volume:  86     ISSN:  1011-1344     ISO Abbreviation:  J. Photochem. Photobiol. B, Biol.     Publication Date:  2007 Feb 
Date Detail:
Created Date:  2006-12-25     Completed Date:  2007-08-06     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8804966     Medline TA:  J Photochem Photobiol B     Country:  Switzerland    
Other Details:
Languages:  eng     Pagination:  177-85     Citation Subset:  IM    
A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninsky Prospect, 31, Building 5, 119071 Moscow, RAS, Russia.
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MeSH Terms
Lipid Bilayers / chemistry*
Membrane Potentials
Models, Molecular
Pyridinium Compounds / chemistry*
Retinoids / chemistry*
Reg. No./Substance:
0/A2E compound; 0/Lipid Bilayers; 0/Liposomes; 0/Phosphatidylcholines; 0/Pyridinium Compounds; 0/Retinoids

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