Localisation of BODIPY-labelled phosphatidylcholines in lipid bilayers.
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 BnPC (n = 3, 5, 7, 9, 11, 13, 15), as well as the energy migration among the Me(4)-BODIPY groups of BnPC:s. The donor-acceptor and the donor-donor experiments strongly suggest that the Me(4)-BODIPY group in BnPC 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 A 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 BnPC:s is also compatible with such a location.
Sachl
Radek
R
Department of Chemistry, Biophysical Chemistry, Umeå University, S-901 87 Umeå, Sweden.
Boldyrev
Ivan
I
Johansson
Lennart B A
LB
D001896:Boron Compounds / Q000737:chemistry*; D004735:Energy Transfer; D005456:Fluorescent Dyes / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D010713:Phosphatidylcholines / Q000032:analysis*
C095489:4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; D001896:Boron Compounds; D005456:Fluorescent Dyes; D008051:Lipid Bilayers; D010713:Phosphatidylcholines