Structural evaluation of phospholipid bicelles for solution-state studies of membrane-associated biomolecules

Biophys J. 2001 Oct;81(4):2163-71. doi: 10.1016/s0006-3495(01)75864-x.

Abstract

Several complementary physical techniques have been used to characterize the aggregate structures formed in solutions containing dimyristoylphosphatidylcholine (DMPC)/dihexanoylphosphatidylcholine (DHPC) at ratios of < or =0.5 and to establish their morphology and lipid organization as that of bicelles. (31)P NMR studies showed that the DMPC and DHPC components were highly segregated over a wide range of DMPC/DHPC ratios (q = 0.05-0.5) and temperatures (15 degrees C and 37 degrees C). Only at phospholipid concentrations below 130 mM did the bicelles appear to undergo a change in morphology. These results were corroborated by fluorescence data, which demonstrated the inverse dependence of bicelle size on phospholipid concentration as well as a distinctive change in phospholipid arrangement at low concentrations. In addition, dynamic light scattering and electron microscopy studies supported the hypothesis that the bicellar phospholipid aggregates are disk-shaped. The radius of the planar domain of the disk was found to be directly proportional to the ratio of DMPC/DHPC and inversely proportional to the total phospholipid concentration when the DMPC/DHPC ratio was held constant at 0.5. Taken together, these results suggest that bicelles with low q retain the morphology and bilayer organization typical of their liquid-crystalline counterparts, making them useful membrane mimetics.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Dimyristoylphosphatidylcholine / chemistry*
  • Lipid Bilayers / chemistry*
  • Magnetic Resonance Spectroscopy
  • Membranes, Artificial*
  • Microscopy, Electron
  • Molecular Mimicry
  • Phosphatidylcholines / chemistry*
  • Phospholipids / chemistry*
  • Solutions / chemistry
  • Spectrometry, Fluorescence

Substances

  • Lipid Bilayers
  • Membranes, Artificial
  • Phosphatidylcholines
  • Phospholipids
  • Solutions
  • 1,2-hexanoylphosphatidylcholine
  • Dimyristoylphosphatidylcholine