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

Biophysical Journal 54: 781-790 (1988)
© 1988 the Biophysical Society

This Article
Right arrow Full Text (PDF)
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 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 Wong, P. T. T.
Right arrow Articles by Mantsch, H. H.
Right arrow Search for Related Content
PubMed
Right arrow Articles by Wong, P. T. T.
Right arrow Articles by Mantsch, H. H.

Reorientational and Conformational Ordering Processes at Elevated Pressures in 1,2-Dioleoyl Phosphatidylcholine

A Raman and Infrared Spectroscopic Study

P. T. T. Wong and H. H. Mantsch

ABSTRACT

Raman and infrared spectra of fully hydrated bilayers of 1,2-dioleoyl phosphatidylcholine (DOPC) were measured at increasing hydrostatic pressures up to -37 kbar. Under ambient conditions aqueous dispersions of DOPC are in the liquid crystalline state. The application of an external hydrostatic pressure induces conformational and dynamic ordering processes in DOPC, which trigger a first-order structural phase transition at 5 kbar from a disordered liquid crystalline state to a highly ordered gel state. In the gel phase the methylene chains of each molecule are fully extended and the two all-trans chain segments on both sides of the rigid cis double bond form a bent structure. The bent oleoyl chains in each molecule, as well as in neighboring molecules are packed parallel to each other. To achieve this parallel interchain packing, the double bonds of the sn-1 and sn-2 chains of each molecule must be aligned at the same position with respect to the bilayer interface which is achieved by a rotation of the C—C bonds in the glycerol moiety in the head group. The extremely strong interchain interactions in the gel phase of DOPC are unique for this lipid with cis dimono-unsaturated acyl chains. Our experimental results suggest that in the pressure-induced gel phase of DOPC the olefinic CH bonds are rotated out of the phase of the bent oleoyl chains and that the oleoyl chains of opposing bilayers bend towards opposite directions.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 1988 by the Biophysical Society.