This Article Full Text Full Text (PDF) 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 HighWire Citing Articles via Google Scholar Google Scholar Articles by Doxastakis, M. Articles by de Pablo, J. J. Search for Related Content PubMed PubMed Citation Articles by Doxastakis, M. Articles by de Pablo, J. J.

A Molecular View of Melting in Anhydrous Phospholipidic Membranes

M. Doxastakis ^*, V. García Sakai , S. Ohtake ^*, J. K. Maranas  and J. J. de Pablo ^*

^* Department of Chemical and Biological Engineering, University of Wisconsin, Madison, Wisconsin; National Institute of Standards and Technology Center for Neutron Research, Gaithersburg, Maryland and Department of Materials Science and Engineering, University of Maryland, College Park, Maryland; and Department of Chemical Engineering and Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania

Correspondence: Address reprint requests to J. J. de Pablo, E-mail: depablo{at}engr.wisc.edu.

A high-flux backscattering spectrometer and a time-of-flight disk chopper spectrometer are used to probe the molecular mobility of model freeze-dried phospholipid liposomes at a range of temperatures surrounding the main melting transition. Using specific deuteration, quasielastic neutron scattering provides evidence that, in contrast to the hydrocarbon chains, the headgroups of the phospholipid molecules do not exhibit a sharp melting transition. The onset of motion in the tails is located at temperatures far below the calorimetric transition. Long-range motion is achieved through the onset of whole-lipid translation at the melting temperature. Atomistic simulations are performed on a multibilayer model at conditions corresponding to the scattering experiments. The model provides a good description of the dynamics of the system, with predictions of the scattering functions that agree with experimental results. The analysis of both experimental data and results of simulations supports a picture of a gradual melting of the heterogeneous hydrophobic domain, with part of the chains spanning increasingly larger volumes and part of them remaining effectively immobile until the thermodynamic phase transition occurs.

This article has been cited by other articles:

				A. V. Popova and D. K. Hincha Effects of Cholesterol on Dry Bilayers: Interactions between Phosphatidylcholine Unsaturation and Glycolipid or Free Sugar Biophys. J., August 15, 2007; 93(4): 1204 - 1214. [Abstract] [Full Text] [PDF]