Localisation of BODIPY-labelled phosphatidylcholines in lipid bilayers

• Published in: Physical chemistry chemical physics : PCCP 2010-06, Vol.12 (23), p.627-634
• Main Authors: Šachl, Radek, Boldyrev, Ivan, Johansson, Lennart B. Å
• Format: Article
• Language: English
• Subjects: Boron Compounds - chemistry; Energy Transfer; Fluorescent Dyes - chemistry; Lipid Bilayers - chemistry; Phosphatidylcholines - analysis
• ISSN: 1463-9076; 1463-9084; 1463-9084
• DOI: 10.1039/b926953c

A series of sn -2 acyl-labelled phosphatidyl-cholines (PC), bearing 4,4-difluoro-1-3-5-7-tetra-methyl-4-bora-3a,4a-diaza- s -indacene-8-yl (Me 4 -BODIPY) at the end of the C n -acyl chains were solubilised in unilamellar vesicles and studied with respect to the order and location of the Me 4 -BODIPY (denoted: B) group. The obtained results are based on time-resolved electronic energy transfer from donors (2-(9-anthroyloxy)-stearic acid) localised in the lipid-water interface to acceptors B n PC ( n = 3, 5, 7, 9, 11, 13, 15), as well as the energy migration among the Me 4 -BODIPY groups of B n PC:s. The donor-acceptor and the donor-donor experiments strongly suggest that the Me 4 -BODIPY group in B n PC tends to loop back close to the lipid-water interface. The Me 4 -BODIPY groups, residing in the two bilayer leaflets, are located at approximately the same depth, and transversally separated by ca. 27 Å for all n -values. Close to the interface, the optimal transversal distribution widens somewhat with increasing length of the sn -2 acyl chain. The obtained order parameter profile of the B n PC:s is also compatible with such a location. sn -2 acyl BODIPY-labelled lipids are transversally separated by 27 Å in DOPC bilayers irrespective of chain lengths.