This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.107.104224v1 93/5/1630    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Cambrea, L. R. Articles by Hovis, J. S. Search for Related Content PubMed PubMed Citation Articles by Cambrea, L. R. Articles by Hovis, J. S.

Effect of Ions on the Organization of Phosphatidylcholine/Phosphatidic Acid Bilayers

Lee R. Cambrea ^*, Farzin Haque ^*, Jeremy L. Schieler , Jean-Christophe Rochet  and Jennifer S. Hovis ^*

^* Department of Chemistry and Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47907

Correspondence: Address reprint requests to Jennifer S. Hovis, Tel.: 765-494-4115; Fax: 765-494-0239; E-mail: jhovis{at}purdue.edu.

Lipid bilayers are two-dimensional fluids. Here, the effect of monovalent ion concentration on the mixing, and consequently the organization, of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/1,2-dioleoyl-sn-glycero-3-phosphate (DOPA) bilayers has been examined. Epifluorescence microscopy was used to visualize the organization. Fluorescence recovery after photobleaching and attenuated total reflection-Fourier transform infrared spectroscopy were used to assess the fluidity of the lipids. At high ionic strength the DOPC and DOPA lipids appear uniformly mixed. Upon lowering the ionic strength, rapid separation is observed. The DOPA-rich regions appear fractal-like and exhibit hysteresis in their properties. The lipids freely exchange between the two regions. These experiments clearly demonstrate the significant effect that electrostatics can have on membrane organization.