help button home button Biophys. J.
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS

Biophysical Journal 64: 1681-1690 (1993)
© 1993 the Biophysical Society

This Article
Right arrow Full Text (PDF)
Right arrow A correction has been published
Right arrow A correction has been published
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Alam, T M
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Alam, T M

Molecular dynamics in lipid bilayers. Anisotropic diffusion in an odd restoring potential.

T M Alam

Department of Chemistry, University of New Mexico, Albuquerque 87131.

ABSTRACT

Recent 2H nuclear magnetic resonance spin relaxation studies have questioned the influence of restoring potential parity on the description of lipid or molecular reorientational dynamics. In biomembranes the polar head groups of lipid and sterol constituents are expected to associate with the aqueous interface; therefore, realistic descriptions of molecular reorientation in bilayer systems should use an odd restoring potential. The multiexponential correlation functions and related spectral density functions for small-step anisotropic diffusion in a pseudo-restoring potential of the form U(beta) = -lambda cos beta are evaluated as a function of molecular ordering <P2(cos beta)>. From analysis of these results the single exponential approximation used in previous investigations is found to overestimate the decay rate at lower order, but is reliable for <P2(cos beta)> > 0.6. The exception to this trend is the decay constant for the G11 (omega; t) correlation function, which is not accurately portrayed by the first-order approximations. A second-order single exponential approximation is presented, and is shown to be equivalent to the weighted sum of the multidecay constants. In general, the potential parity is found to have only minor effects on the spin relaxation rates obtained to describe molecular reorientation in lipid bilayers.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 1993 by the Biophysical Society.