Acyl-Chain Mismatch Driven Superlattice Arrangements in DPPC/DLPC/Cholesterol Bilayers

6533b834fe1ef96bd129d857

RESEARCH PRODUCT

Acyl-Chain Mismatch Driven Superlattice Arrangements in DPPC/DLPC/Cholesterol Bilayers

Pentti Somerharju Jorma A. Virtanen Brian L Cannon Kwan Hon Cheng Anthony Lewis Juyang Huang

subject

Diphenylhexatriene 1 2-Dipalmitoylphosphatidylcholine Cholesterol oxidase Superlattice Lipid Bilayers Analytical chemistry Infrared spectroscopy Fluorescence Polarization 010402 general chemistry Mole fraction 01 natural sciences Article 03 medical and health sciences chemistry.chemical_compound Phosphatidylcholine Spectroscopy Fourier Transform Infrared polycyclic compounds Materials Chemistry Physical and Theoretical Chemistry Lipid bilayer 030304 developmental biology 0303 health sciences Cholesterol Oxidase Cholesterol technology industry and agriculture 0104 chemical sciences Surfaces Coatings and Films Crystallography Cholesterol chemistry Cholesterol oxidase activity 13. Climate action Acyl chain Phosphatidylcholines lipids (amino acids peptides and proteins)Fluorescence anisotropy

description

Fluorescence and infrared spectroscopy and cholesterol oxidase activity were employed to investigate the effect of phosphatidylcholine (PC) acyl chain length mismatch on the lateral organizations of lipids in liquid-ordered dipalmitoyl-PC/dilauroyl-PC/cholesterol (DPPC/DLPC/CHOL) bilayers. Plots of steady-state fluorescence emission anisotropy of diphenylhexatriene (DPH) labeled PC (DPH-PC) embedded in the DPPC/DLPC/CHOL bilayers revealed significant peaks at several DPPC mole fractions (Y(DPPC)) when the cholesterol mole fraction (X(CHOL)) was fixed to particular values. Analogously, the DPH-PC anisotropy peaked at several critical X(CHOL)'s when Y(DPPC) was fixed. Acyl chain C-H and C horizontal lineO vibrational peak frequencies of native PC as well as the activity of cholesterol oxidase also revealed dips and peaks at similar Y(DPPC)'s. Importantly, most of the observed peaks/dips coincide with the critical mole fractions predicted by the Superlattice (SL) model. A three-dimensional map of DPH-PC anisotropy versus composition in the range 0.32 <or= X(CHOL) <or= 0.50; 0.54 <or= Y(DPPC) <or= 0.72 revealed a prominent peak at (X(CHOL), Y(DPPC)) approximately (0.42, 0.64). This suggests a simultaneous presence of two different types of superlattices, one where cholesterol is the quest molecule in a PC host lattice and another where DPPC is the guest in the DLPC host lattice. Time-resolved measurements of DPH-PC fluorescence indicated the existence of an ordered, rotationally hindered environment of acyl chains at that "critical" composition consistent with the existence of SL arrangements. We propose that beside CHOL/PC superlattices, DPPC, and DLPC as well tend to adopt regular SL-like lateral distributions relative to each other, presumably because the less hydrophobic DLPC molecule is slightly displaced toward the aqueous phase, thus allowing more room and mobility for the head groups of both DPPC and DLPC as well as for the acyl chain tails of DPPC. The parallel presence of two kinds of superlattices, that is, CHOL/PC-SL and DPPC/DLPC-SL as demonstrated here, has intriguing implications regarding lipid homeostasis of eukaryote membranes.

year	journal	country	edition	language
2010-08-06	The Journal of Physical Chemistry B

https://doi.org/10.1021/jp107432k