Biophysical Journal 15: 1117-1124 (1975)
© 1975 the Biophysical Society

This Article 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 Rand, R P Articles by Larsson, K Search for Related Content PubMed PubMed Citation Articles by Rand, R P Articles by Larsson, K

Tilted hydrocarbon chains of dipalmitoyl lecithin become perpendicular to the bilayer before melting.

ABSTRACT

Differential scanning calorimetry studies of dipalmitoyl lecithin show two reversible transitions as the temperature is changed between 20 and 50 degrees C. A pretransition endotherm occurs at 35 degrees C prior to the main chain melting endotherm which occurs at 42 degrees C. X-ray diffraction studies show that below 33 degrees C the chains of the lecithin are fully extended, packed in a hexagonal crystalline lattice but tilted with respect to the plane of the bilayer. Between 35 and 42 degrees C the chains are similarly packed but oriented perpendicular to the bilayer plane. Above 44 degrees C the chains are "melted" or disordered. Monolayer studies of dipalmitoyl lecithin using continuous recording of pressure with molecular area reveal the existence of two solid condensed phases corresponding to these tilted and verticle chain structures. The tilted to perpendicular transition would account for the pretransition endotherm of the lipid; the crystalline to melted change corresponds to the larger transition observed at 42 degrees C.

This article has been cited by other articles:

				M. Ge and J. H. Freed Hydration, Structure, and Molecular Interactions in the Headgroup Region of Dioleoylphosphatidylcholine Bilayers: An Electron Spin Resonance Study Biophys. J., December 1, 2003; 85(6): 4023 - 4040. [Abstract] [Full Text] [PDF]