Physical and photophysical characterization of a BODIPY phosphatidylcholine as a membrane probe.
Lipids containing the dimethyl BODIPY fluorophore are used in cell biology because their fluorescence properties change with fluorophore concentration (C.-S. Chen, O. C. Martin, and R. E. Pagano. 1997. Biophys J. 72:37-50). The miscibility and steady-state fluorescence behavior of one such lipid, 1-palmitoyl-2-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl)-sn-glycero-3-phosphocholine (PBPC), have been characterized in mixtures with 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC). PBPC packs similarly to phosphatidylcholines having a cis-unsaturated acyl chain and mixes nearly ideally with SOPC, apparently without fluorophore-fluorophore aggregation. Increasing PBPC mole fraction from 0.0 to 1.0 in SOPC membranes changes the emission characteristics of the probe in a continuous manner. Analysis of these changes shows that emission from the excited dimethyl BODIPY monomer self quenches with a critical radius of 25.9 A. Fluorophores sufficiently close (< or =13.7 A) at the time of excitation can form an excited dimer, emission from which depends strongly on total lipid packing density. Overall, the data show that PBPC is a reasonable physical substitute for other phosphatidylcholines in fluid membranes. Knowledge of PBPC fluorescence in lipid monolayers has been exploited to determine the two-dimensional concentration of SOPC in unilamellar, bilayer membranes.
Dahim
Mohammed
M
The Hormel Institute, University of Minnesota, Austin, Minnesota 55912 USA.
Mizuno
Nancy K
NK
Li
Xin-Min
XM
Momsen
William E
WE
Momsen
Maureen M
MM
Brockman
Howard L
HL
D055592:Biophysical Phenomena; D001703:Biophysics; D001896:Boron Compounds / Q000737:chemistry*; D002462:Cell Membrane / Q000378:metabolism*; D008051:Lipid Bilayers / Q000737:chemistry; D008962:Models, Theoretical; D010713:Phosphatidylcholines / Q000737:chemistry*; D011312:Pressure; D013050:Spectrometry, Fluorescence; D013696:Temperature
C472085:1-palmitoyl-2-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl)-sn-glycero-3-phosphocholine; C095489:4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; D001896:Boron Compounds; D008051:Lipid Bilayers; D010713:Phosphatidylcholines