title: Effect of hydrogen bonding on the rotational and translational dynamics of a headgroup-bound chromophore in bilayer lipid membranes.
abstract: We have studied the interactions of the chromophore 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-7-nitro-2-1,3-benzoxadiazol-4-yl (18:1 NBD-PE) imbedded in the headgroup region of bilayer lipid membranes consisting of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-dioleoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (DOPG). We have examined the molecular and mesoscale dynamics of the chromophore using time-correlated single photon counting (TCSPC) to measure rotational diffusion dynamics in lipid vesicles and fluorescence recovery after pattern photobleaching (FRAPP) to determine translational diffusion coefficients and mobile fractions in supported lipid bilayers. TCSPC data reveal that chromophore rotational diffusion rates in DOPG vesicles are statistically the same as in DOPC and mixed DOPC/DOPG vesicles, suggesting that the NBD-PE chromophore does not interact strongly with the headgroup region of these bilayers; however, FRAPP experiments show that lateral diffusion is statistically lower in mixed DOPC/DOPG-supported bilayers than in DOPC-supported bilayers. These results suggest that bilayers containing DOPG likely undergo interlipid headgroup hydrogen bonding interactions that suppress translational diffusion.
authors.affiliation: Department of Chemical Engineering and Materials Science and Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA.
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Greiner
authors.forename: Heather A
authors.initials: HA
authors.lastname: Pillman
authors.forename: R M
authors.initials: RM
authors.lastname: Worden
authors.forename: G J
authors.initials: GJ
authors.lastname: Blanchard
authors.forename: R Y
authors.initials: RY
authors.lastname: Ofoli
mesh_terms: D016880:Anisotropy; D004058:Diffusion; D036681:Fluorescence Recovery After Photobleaching; D005456:Fluorescent Dyes / Q000737:chemistry*; D006860:Hydrogen Bonding; D008051:Lipid Bilayers / Q000737:chemistry*; D008563:Membrane Lipids / Q000737:chemistry; D015394:Molecular Structure; D010713:Phosphatidylcholines / Q000737:chemistry; D010714:Phosphatidylethanolamines / Q000737:chemistry*; D010715:Phosphatidylglycerols / Q000737:chemistry; D012399:Rotation
chemical_list: D005456:Fluorescent Dyes; D008051:Lipid Bilayers; D008563:Membrane Lipids; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010715:Phosphatidylglycerols; C042077:N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)phosphatidylethanolamine; C051388:1,2-dioleoyl-sn-glycero-3-phosphoglycerol; C020888:1,2-dielaidoylphosphatidylethanolamine; C017251:1,2-oleoylphosphatidylcholine